WO2012127854A1 - Optical information device and tracking method - Google Patents

Optical information device and tracking method Download PDF

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Publication number
WO2012127854A1
WO2012127854A1 PCT/JP2012/001918 JP2012001918W WO2012127854A1 WO 2012127854 A1 WO2012127854 A1 WO 2012127854A1 JP 2012001918 W JP2012001918 W JP 2012001918W WO 2012127854 A1 WO2012127854 A1 WO 2012127854A1
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WO
WIPO (PCT)
Prior art keywords
track
resonance
elements
light
tracking
Prior art date
Application number
PCT/JP2012/001918
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French (fr)
Japanese (ja)
Inventor
竜也 高岡
和田　秀彦
佐野　晃正
松崎　圭一
Original Assignee
パナソニック株式会社
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Publication of WO2012127854A1 publication Critical patent/WO2012127854A1/en

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0901—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following only
    • G11B7/0903—Multi-beam tracking systems
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
    • G11B7/0857—Arrangements for mechanically moving the whole head
    • G11B7/08576—Swinging-arm positioners
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372—Lenses
    • G11B2007/13727—Compound lenses, i.e. two or more lenses co-operating to perform a function, e.g. compound objective lens including a solid immersion lens, positive and negative lenses either bonded together or with adjustable spacing

Definitions

  • the present invention relates to an optical information apparatus for recording or reproducing information on an information recording medium having a track, and a tracking method for the optical information apparatus.
  • FIG. 50 is a top view showing the configuration of the near-field optical head in the prior art
  • FIG. 51 is a side view showing the configuration of the near-field optical head in the prior art.
  • the near-field light head includes a light source 802, a prism 803 that transmits the emitted light LB of the light source 802, and a scatterer 804 that generates near-field light NL when the emitted light LB enters.
  • the heat dissipation material 805 is fixed to the light source 802 and dissipates heat generated by the light source 802.
  • the detection element 806 detects reproduction light from the optical disc 801.
  • a light source 802, a prism 803, a scatterer 804, a heat dissipation material 805, and a detection element 806 are held by a slider 807.
  • the slider 807 is held by a suspension 808 so that the distance between the optical disc 801 and the scatterer 804 is constant.
  • the near-field light NL generated from the scatterer 804 changes the crystal phase of the optical disk 801, which is a phase change material, to an amorphous phase, thereby forming a recording mark and recording information on the optical disk 801.
  • the information is detected by detecting the intensity change of the scattered light returning from the optical disk 801. Playback starts from 801.
  • the light source 802, the prism 803, the scatterer 804, the heat radiation member 805, and the detection element 806 are held by the slider 807 to form a so-called near-field optical probe slider. Therefore, it is possible to realize a near-field optical head device that records or reproduces information on the optical disc 801 with high density by using the near-field light NL while achieving a very small size.
  • FIG. 52 is a schematic diagram showing a configuration of a high-density probe memory reproducing device in the prior art
  • FIG. 53 is a perspective view of a principal part showing a probe attachment state and a deformation state in the conventional technology.
  • an information recording medium 901 includes a recording unit 902 formed in a track shape.
  • the information recording medium 901 is rotated by a rotating element 903.
  • the plurality of probes 904 are held by a slider 905 and a suspension 906 in a range where they can come into contact with one recording unit 902.
  • the positions of the plurality of probes 904 change as shown in FIG. 53 by contacting the recording unit 902.
  • the suspension 906 is held by a driving element 907 and is driven in a direction perpendicular to the track.
  • Incident light 908 from a light source (not shown) is applied to the plurality of probes 904.
  • the plurality of detection elements 910 detect reflected light 909 from the plurality of probes 904. Thereby, the displacement of the plurality of probes 904 is detected.
  • the arithmetic circuit 911 calculates and outputs a reproduction signal and a tracking signal based on a plurality of detection information obtained from the plurality of detection elements 910.
  • the tracking signal is input to the drive element 907.
  • the drive element 907 drives the suspension 906 according to the tracking signal. Thereby, tracking of the plurality of probes 904 is performed.
  • the position of the probe in order for the probe to detect the recording portion, the position of the probe must be displaced by the interaction with the recording portion. Therefore, the relative positions of the plurality of probes and the recording unit are changed, and the detection signal does not reflect only the distance in the direction perpendicular to the track between the plurality of probes and the recording unit. Had.
  • the present invention has been made to solve the above-described problems, and an object thereof is to provide an optical information device and a tracking method capable of performing stable and highly accurate tracking.
  • An optical information device is an optical information device for recording or reproducing information on an information recording medium having a track, and a light source, light from the light source is incident thereon, and the information recording medium is mutually connected.
  • a plurality of resonant elements that change the resonance state according to the distance from the track, and the positions of the plurality of resonant elements are shifted in a direction perpendicular to the track, and between the plurality of resonant elements A holding element that holds the distance fixed, a first detection element that individually detects a change in the resonance state of each of the plurality of resonance elements, and the resonance state that is detected by the first detection element
  • a tracking signal calculation circuit for calculating a tracking signal based on the change of the tracking signal, and the holding element in the track according to the tracking signal calculated by the tracking signal calculation circuit Comprising a first moving element that moves in a straight direction, the.
  • the holding element is arranged by shifting the position of the plurality of resonance elements in a direction perpendicular to the track, and holds the distance between the plurality of resonance elements fixed at a constant value.
  • the first detection element individually detects a change in the resonance state of each of the plurality of resonance elements.
  • the tracking signal calculation circuit calculates a tracking signal based on a change in the resonance state detected by the first detection element.
  • the first moving element moves the holding element in a direction perpendicular to the track in accordance with the tracking signal calculated by the tracking signal calculation circuit.
  • the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is held constant, so that the interaction with the information recording medium is possible.
  • the relative positions of the plurality of resonance elements and the tracks do not change. Therefore, stable and highly accurate tracking that depends only on the displacement from the track position can be performed.
  • the detection signal since a change in the resonance state of each of the plurality of resonance elements is individually detected and a tracking signal is calculated based on the detected change in the resonance state, the detection signal has an optical constant around the plurality of resonance elements.
  • a tracking signal having a high degree of modulation can be obtained with respect to a minute positional deviation from the track, which reacts sensitively to changes. Therefore, stable and highly accurate tracking can be performed.
  • FIG. 1 It is the schematic which shows the structure of the optical information apparatus in Embodiment 1 of this invention. It is a perspective view which shows the structure of the slider shown in FIG. It is a side view which shows the structure of the slider shown in FIG. It is a top view which shows the structure of the slider shown in FIG. It is an enlarged view which shows the metal antenna in Embodiment 1 of this invention.
  • (A) is a graph which shows the change of the near-field light intensity with respect to the distance from the track
  • (B) is the intensity
  • (C) is a graph which shows the intensity
  • (C) is a graph which shows the intensity
  • (C) is a graph which shows the intensity
  • it is a figure which shows the metal antenna which is a square plate shape.
  • Embodiment 1 and 2 of this invention it is a figure which shows the metal antenna which is a disk shape.
  • Embodiment 1 and 2 of this invention it is a figure which shows the metal antenna which is a probe shape. It is the schematic which shows the structure of the optical information apparatus in Embodiment 3 of this invention. It is a perspective view which shows the structure of the some metal antenna shown in FIG. It is a top view which shows the structure of the some metal antenna shown in FIG. (A) is a graph which shows the change of the scattered light intensity from a metal antenna with respect to the distance from the track
  • Embodiment 3 of this invention it is a figure which shows the metal antenna which is a fan-plate shape. In Embodiment 3 of this invention, it is a figure which shows the metal antenna which is a bowtie shape. In Embodiment 3 of this invention, it is a figure which shows the metal antenna which is a nano beak shape. It is a figure which shows the example which arrange
  • Embodiment 3 of this invention it is a figure which shows the example arrange
  • FIG. 31 is a top view showing the configuration of the slider shown in FIG. 30.
  • FIG. (A) shows a signal (a ⁇ (te1 ⁇ te0)) obtained by weighting the difference between the detection signal te1 and the detection signal te0 with respect to the positional deviation from the track and the difference between the detection signal te2 and the detection signal te0.
  • Embodiment 7 is a graph showing a change in intensity of a signal (b ⁇ (te2-te0)) weighted with a correction value b, and (B) is a graph showing a change in intensity of the tracking signal with respect to a positional deviation from the track.
  • it is a figure shown for demonstrating another example of arrangement
  • it is a figure for demonstrating another example of arrangement
  • FIG. 1 is a schematic diagram showing a configuration of an optical information device according to Embodiment 1 of the present invention.
  • 2 is a perspective view showing the configuration of the slider shown in FIG. 1
  • FIG. 3 is a side view showing the configuration of the slider shown in FIG. 1
  • FIG. 4 is a top view showing the configuration of the slider shown in FIG. FIG.
  • the optical information device includes semiconductor laser elements 107a, 107b, 107c, metal antennas 108a, 108b, 108c, waveguides 109a, 109b, 109c, light receiving elements 110a, 110b, 110c, a motor 103, and a slider 104.
  • a disc 101 as an information recording medium has a track 112 in which fine particles 102 made of a phase change material on which information is recorded or reproduced are arranged in a line.
  • the disk 101 is rotated by a motor 103 that holds and rotates the disk 101.
  • the phase change material constituting the fine particles 102 for example, a material made of an alloy such as Ge, Sb, Te, Bi, Tb, Fe, or Co can be considered.
  • a slider 104 is disposed as a holding element that holds the resonance element.
  • the slider 104 which is a holding element, is arranged by shifting the positions of the plurality of resonance elements (metal antennas 108b and 108c) in the direction perpendicular to the track 112, and holding the distance between the plurality of resonance elements fixed at a constant value.
  • the slider 104 is always pressed against the disk 101 by a suspension 105 as a spring element.
  • the suspension 105 also functions as a second moving element that moves a plurality of resonance elements in a direction perpendicular to the surface of the disk 101.
  • the suspension 105 is moved in a direction perpendicular to the track 112 by an actuator 106 as a first moving element.
  • the slider 104 is moved in a direction perpendicular to the track 112. That is, the actuator 106 as the first moving element moves the holding element (slider 104) in a direction perpendicular to the track 112 in accordance with the tracking signal.
  • the slider 104 scans while sliding on the disk 101.
  • the second moving element that moves the plurality of resonant elements in the direction perpendicular to the surface of the information recording medium includes the suspension 105 (spring element). Yes. At this time, the suspension 105 brings the slider 104 and the disk 101 into contact with each other.
  • semiconductor laser elements 107 a, 107 b, and 107 c indicate light sources.
  • a semiconductor laser element is used as the light source.
  • the polarization direction of the light emitted from the semiconductor laser elements 107 a, 107 b and 107 c is a direction perpendicular to the surface of the disk 101.
  • the metal antennas 108a, 108b, and 108c are resonance elements that excite plasmon resonance by light from the semiconductor laser elements 107a, 107b, and 107c.
  • the metal antennas 108b and 108c, which are resonance elements, interact with the disk 101, and the resonance state changes according to the distance from the track 112.
  • tracking metal antennas 108b and 108c are arranged side by side in a direction perpendicular to the track 112 with the recording or reproduction metal antenna 108a as the center.
  • the metal antennas 108b and 108c are disposed at positions separated from the metal antenna 108a by a distance P in the direction perpendicular to the track 112, respectively.
  • the distance P is a quarter of the tracking period (track pitch) Tp.
  • the distance (2P) in the direction perpendicular to the track 112 between the metal antenna 108b and the metal antenna 108c is fixed to one half of the tracking period Tp.
  • the light emitted from the three semiconductor laser elements 107a, 107b and 107c is individually guided to the three metal antennas 108a, 108b and 108c by the three waveguides 109a, 109b and 109c as optical elements for guiding the light, Excites plasmon resonance.
  • the three waveguides 109a, 109b and 109c are arranged non-parallel to each other in order to suppress waveguide mode coupling.
  • the waveguides 109a, 109b, and 109c are arranged so that the distance between the waveguide 109a and the waveguide 109b and the distance between the waveguide 109a and the waveguide 109c increase as the distance from the metal antennas 108a, 108b, and 108c increases. Has been.
  • Light receiving elements 110a, 110b, and 110c as detection elements are attached to the apex portions of the metal antennas 108a, 108b, and 108c, respectively.
  • the light receiving elements 110a, 110b and 110c individually detect the intensity of near-field light generated from the metal antennas 108a, 108b and 108c. That is, the light receiving elements 110b and 110c, which are first detection elements, individually detect changes in the resonance states of the plurality of resonance elements (metal antennas 108b and 108c).
  • the first detection element that individually detects and outputs the change in the resonance state of each of the plurality of resonance elements is the plurality of resonance elements (metal antennas).
  • 108b and 108c) includes a plurality of light receiving elements 110b and 110c arranged in a range in which near-field light generated from 108b and 108c) can be detected.
  • the shape of the metal antennas 108a, 108b and 108c is a triangular flat plate shape such as gold, silver, copper, titanium, aluminum or chrome as shown in FIG.
  • the metal antenna 108a is arranged so that the vertex of the triangle is closest to the surface of the fine particle 102, and strong near-field light is generated in the vicinity of the vertex of the triangle when plasmon resonance is excited.
  • the interaction between two metal particles appears prominently when the distance between the metal particles is several tens of nanometers or less, and becomes more prominent at a few nanometers (Confined plasmas in nanofabricated particulates: experimental observers. interactions, L. Gunnarsson et.al., J. Phys. Chem.
  • the distance between the metal antenna 108a and the surface of the fine particle 102 is preferably several tens of nm or less, and more preferably several nm.
  • the metal antennas 108b and 108c are also arranged in the same manner as the metal antenna 108a, and strong near-field light is generated near the apex of the triangle.
  • FIG. 6A is a graph showing a change in near-field light intensity with respect to the distance from the track 112 of the metal antennas 108a, 108b, and 108c.
  • FIG. 6B is a graph showing changes in the intensity of the detection signal te1 from the light receiving element 110b and the detection signal te2 from the light receiving element 110c.
  • FIG. 6C is a graph showing a change in intensity of the tracking signal TE, which is the difference between the detection signal te1 and the detection signal te2 output from the operational amplifier 111.
  • the resonance condition of plasmon resonance greatly depends on the dielectric constant of the medium around the resonance element. Therefore, if the shape of the metal antennas 108a, 108b and 108c is designed so that the plasmon resonance condition is satisfied on the fine particle 102 with respect to the frequency of light of the semiconductor laser elements 107a, 107b and 107c, the generated near-field light is generated. As shown in FIG. 6A, the intensity is maximum at the track position (position where the distance from the track 112 coincides with the tracking period Tp) and minimum at the position where the distance from the track 112 is half the tracking period Tp. Become.
  • the detection signal of the light receiving element 110a is output as a reproduction signal.
  • the detection signals te1 and te2 of the light receiving elements 110b and 110c are input to the operational amplifier 111 that functions as a tracking signal calculation circuit.
  • the light receiving elements 110b and 110c output detection signals te1 and te2 representing changes in the resonance states of the plurality of resonance elements (metal antennas 108b and 108c).
  • the operational amplifier 111 calculates a level difference between the detection signal te1 and the detection signal te2 output by the light receiving elements 110b and 110c as the tracking signal TE.
  • the operational amplifier 111 serving as the tracking signal calculation circuit calculates the tracking signal TE based on the change in the resonance state of each of the plurality of resonance elements (metal antennas 108b and 108c) detected by the light receiving elements 110b and 110c. .
  • the tracking metal antennas 108b and 108c are set apart from the recording or reproducing metal antenna 108a by a quarter of the tracking period Tp in the direction perpendicular to the track 112, respectively. ing. Therefore, the difference between the detection signal te1 and the detection signal te2 can be maximized, and a highly accurate tracking signal TE can be obtained.
  • the output tracking signal TE is input to the actuator 106.
  • the actuator 106 drives the slider 104 in a direction perpendicular to the track 112 in response to the tracking signal TE.
  • the metal antennas 108a, 108b, and 108c are arranged perpendicular to the surface of the disk 101, and the plasmon resonance is excited by the polarized light perpendicular to the surface of the disk 101. Is done. For this reason, the area on the disk 101 which interacts with the metal antennas 108a, 108b and 108c is reduced, and high resolution can be obtained.
  • light from the semiconductor laser elements 107a, 107b, and 107c is individually incident on the metal antennas 108a, 108b, and 108c using the plurality of waveguides 109a, 109b, and 109c.
  • the near-field light intensity of each of the metal antennas 108a, 108b, and 108c is directly detected individually by the light receiving elements 110a, 110b, and 110c attached to the metal antennas 108a, 108b, and 108c. For this reason, a highly accurate and highly efficient tracking signal can be obtained.
  • the distance between the metal antennas 108a, 108b and 108c and the fine particles 102 in the direction perpendicular to the surface of the disk 101 is not changed. Therefore, a stable and highly accurate tracking signal that depends only on the displacement in the direction perpendicular to the track 112 can be obtained.
  • the slider 104 slides on the disk 101. For this reason, the distance between the metal antennas 108a, 108b and 108c and the surface of the disk 101 can always be kept constant without using a complicated configuration. For this reason, stable tracking can be performed.
  • a disk is used as the information recording medium.
  • the slider 104 may be configured to move over the entire area of the disk, and the shape of the information recording medium is not limited to a circle.
  • FIG. 7 is a diagram for explaining a slider driving method in a modification of the first embodiment of the present invention.
  • the optical information device in the modification of the first embodiment moves the slider 104 in a direction perpendicular to the track 112 and the slider 104 moves in a direction parallel to the track 112.
  • a drive element 115 a drive element 115.
  • the information recording medium 113 has a card shape, for example, and is fixed at a predetermined position.
  • the slider 104 is driven on the fixed information recording medium 113 by driving elements 114 and 115 to scan the entire area of the information recording medium 113. Even with such a configuration, the gist of the present invention is not impaired.
  • the disk 101 corresponds to an example of an information recording medium
  • the semiconductor laser elements 107b and 107c correspond to an example of a light source
  • the metal antennas 108b and 108c correspond to an example of a plurality of resonance elements.
  • the slider 104 corresponds to an example of a holding element
  • the light receiving elements 110b and 110c correspond to an example of a first detection element and a plurality of light receiving elements
  • the operational amplifier 111 corresponds to an example of a tracking signal arithmetic circuit
  • the actuator 106 The suspension 105 corresponds to an example of a first moving element
  • the suspension 105 corresponds to an example of a second moving element
  • the waveguides 109b and 109c correspond to an example of a plurality of waveguides.
  • FIG. 8 is a flowchart for explaining the tracking method according to the first embodiment of the present invention.
  • the semiconductor laser elements 107a, 107b, and 107c which are light sources, emit light, and enter the metal antennas 108a, 108b, and 108c to excite plasmon resonance.
  • the metal antennas 108 a, 108 b and 108 c are designed so that the plasmon resonance condition is satisfied on the fine particle 102. Plasmon resonance weakens as the positional deviation from the track increases.
  • the light receiving elements 110a, 110b, and 110c individually detect changes in the resonance state of the metal antennas 108a, 108b, and 108c, and output a reproduction signal, a detection signal te1, and a detection signal te2. .
  • the intensity of near-field light generated by plasmon resonance increases as the plasmon resonance increases.
  • the light receiving elements 110a, 110b, and 110c individually detect the intensity of near-field light generated around the metal antennas 108a, 108b, and 108c, so that the resonance states of the individual metal antennas 108a, 108b, and 108c are detected. Changes can be detected.
  • the intensity of the near-field light generated by plasmon resonance shows a change as shown in FIG. 6A with respect to the distance from the track, becomes a maximum value at the track position, and is a position away from the track position by half of the tracking period Tp. Becomes the minimum value.
  • the tracking metal antennas 108b and 108c are separated from the recording or reproduction metal antenna 108a by a quarter of the tracking period Tp in a direction perpendicular to the track (tracking direction). is set up. Therefore, the light receiving elements 110b and 110c obtain detection signals te1 and te2 as shown in FIG.
  • the operational amplifier 111 as an arithmetic circuit calculates the tracking signal TE based on the change in the resonance state detected by the light receiving elements 110b and 110c.
  • the operational amplifier 111 calculates the difference between the detection signal te1 and the detection signal te2 as the tracking signal TE.
  • Detection signals te1 and te2 from the light receiving elements 110b and 110c are input to the operational amplifier 111.
  • the operational amplifier 111 amplifies the difference between the detection signal te1 and the detection signal te2 and outputs it as a tracking signal TE.
  • the tracking metal antennas 108b and 108c are installed apart from the recording or reproducing metal antenna 108a by a quarter of the tracking period Tp in the direction perpendicular to the track. ing.
  • the tracking signal TE has a maximum or minimum value at a position where the positional deviation from the track becomes a quarter of the tracking period Tp, and a position where the positional deviation from the track becomes a half of the tracking period Tp. 0.
  • the actuator 106 moves the slider 104 in a direction perpendicular to the track in accordance with the tracking signal TE calculated by the operational amplifier 111.
  • the tracking signal TE calculated by the operational amplifier 111 is output to the actuator 106.
  • the actuator 106 drives the suspension 105 according to the tracking signal TE to move the slider 104 in a direction perpendicular to the track.
  • Embodiment 1 when the tracking signal TE is a positive value, the actuator 106 drives the suspension 105 so that the slider 104 moves toward the metal antenna 108b. If the tracking signal TE is a negative value, the actuator 106 drives the suspension 105 so that the slider 104 moves toward the metal antenna 108c.
  • the recording or reproducing metal antenna 108a can be constantly and accurately tracked with respect to the fine particles 102.
  • the operational amplifier 111 amplifies the difference between the detection signals te1 and te2 from the light receiving elements 110b and 110c to create the tracking signal TE.
  • the optical information device includes the operational amplifier 111 and the actuator.
  • a low-pass filter may be provided between the low-pass filter 106 and the low-pass filter may remove the high-frequency component output from the operational amplifier 111 and output an average value of the difference between the detection signals te1 and te2 as the tracking signal TE.
  • the tracking method according to the first embodiment is a tracking method in an optical information device that records or reproduces information on an information recording medium having a track, and interacts with the information recording medium, and is a distance from the track.
  • the tracking signal calculation step for calculating the tracking signal based on the change in the resonance state, and the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track according to the tracking signal calculated in the tracking signal calculation step.
  • the holding element that holds the fixed distance between the plurality of resonant elements is fixed to the one perpendicular to the track. Comprising a moving step of moving, to.
  • the positions of the plurality of resonance elements whose resonance states change according to the distance from the track are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is fixed and held constant.
  • the relative position between the plurality of resonance elements and the information recording position on the track does not change due to the interaction. For this reason, a stable and highly accurate tracking signal depending only on the displacement from the track position can be obtained.
  • the resonance state is sensitive to changes in the optical constants around the resonance element. For this reason, even if the information recording state on the track is an information recording state not accompanied by a change in surface shape, tracking can be performed stably and with high accuracy.
  • the change in the resonance state of the plurality of resonance elements is individually detected by the plurality of light receiving elements, and the difference between the detection signals is output as a tracking signal.
  • the detection signal reacts sensitively to changes in the optical constants around the resonant element, and a tracking signal having a high degree of modulation with respect to a positional deviation from a minute track can be obtained. For this reason, a stable and highly accurate tracking signal can be obtained.
  • FIG. 9 is a schematic diagram showing the configuration of the optical information device according to the second embodiment of the present invention.
  • 10 is a perspective view showing the configuration of the slider shown in FIG. 9
  • FIG. 11 is a side view showing the configuration of the slider shown in FIG. 9
  • FIG. 12 is a top view showing the configuration of the slider shown in FIG. FIG. 9 to 12, the same components as those in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof is omitted.
  • the optical information device includes semiconductor laser elements 107a, 107b, and 107c, metal antennas 128a, 128b, and 128c, waveguides 129a, 129b, and 129c, light receiving elements 120a, 120b, and 120c, a motor 103, and a slider 124.
  • a disk 101 having fine particles 102 arranged in a track shape is fixed to and held by a motor 103.
  • the slider 124 as a holding element is arranged by shifting the positions of the metal antennas 128a, 128b and 128c as resonance elements in the direction perpendicular to the track 112, and the distance between the metal antennas 128a, 128b and 128c is fixed. And hold.
  • Metal antennas 128b and 128c which are resonant elements, receive light from semiconductor laser elements 107b and 107c, interact with disk 101, and the resonance state changes according to the distance from track 112.
  • the air slider 132 moves the metal antennas 128a, 128b, and 128c in a direction perpendicular to the surface of the disk 101.
  • the suspension 125 is composed of a spring element.
  • the slider 124 and the air slider 132 are held facing the disk 101 by the suspension 125.
  • the distance between the slider 124 and the disk 101 is kept constant by using a technique similar to that of a flying head employed in a hard disk drive.
  • the second moving element that moves the plurality of resonant elements in the direction perpendicular to the surface of the information recording medium includes the suspension 125 (spring element). Yes.
  • the suspension 125 keeps the distance between the disk 101, the slider 104, and the air slider 132 constant by the force of the airflow flowing between the slider 104 and the air slider 132 and the disk 101.
  • the suspension 125 is driven in a direction perpendicular to the track 112 by the actuator 106.
  • the actuator 106 serving as the first moving element moves the holding element (slider 124) in a direction perpendicular to the track 112 in accordance with the tracking signal.
  • the slider 124 scans the disk 101.
  • the metal antennas 128a, 128b, and 128c are formed of triangular plates such as gold, silver, copper, titanium, aluminum, or chrome.
  • the metal antennas 128a, 128b, and 128c are arranged so that the apex of the triangle is closest to the surface of the fine particle 102, and strong near-field light is generated near the apex of the triangle when plasmon resonance is excited.
  • the distance between the metal antennas 128a, 128b and 128c and the surface of the fine particles 102 is preferably several tens of nm or less, and more preferably several nm.
  • the slider 124 has a stepped step in the direction perpendicular to the track 112 on the end surface of the track 112 in the longitudinal direction.
  • the stepped end face has three faces that are different in position in the longitudinal direction of the track 112.
  • the waveguides 129a, 129b and 129c individually guide light from the semiconductor laser elements 107a, 107b and 107c to the metal antennas 128a, 128b and 128c.
  • the waveguides 129a, 129b and 129c individually guide the reflected light from the metal antennas 128a, 128b and 128c to the light receiving elements 120a, 120b and 120c.
  • the light receiving elements 120a, 120b and 120c are arranged in the vicinity of the semiconductor laser elements 107a, 107b and 107c, respectively.
  • the light receiving elements 120a, 120b, and 120c individually detect changes in the resonance states of the metal antennas 128a, 128b, and 128c.
  • Each of the light receiving elements 120a, 120b, and 120c is attached to each of the plurality of waveguides 129a, 129b, and 129c, and individually detects the reflected light from the metal antennas 128a, 128b, and 128c.
  • the first detection elements that individually detect and output changes in the resonance states of the plurality of resonance elements are the plurality of light receiving elements 120b and 120c.
  • the optical information device includes a plurality of waveguides 129b and 129c that guide light from the plurality of resonance elements (metal antennas 128b and 128c) to the plurality of light receiving elements 120b and 120c.
  • a total of three metal antennas 128a, 128b, and 128c are fixed to the stepped end face of the slider 124, one each. Plasmon resonance is excited by light from the semiconductor laser elements 107a, 107b, and 107c guided by the plurality of waveguides 129a, 129b, and 129c.
  • the interaction between two metal particles appears prominently when the distance between the metal particles is several tens of nanometers or less (Confined plasmas in nanofabricated partialspars: experiential severinstrands. Al., J. Phys. Chem. B, 2005, 109, 1079-1087). Therefore, the length L in the longitudinal direction of the track between the metal antenna 128a and the metal antenna 128b and the length L in the longitudinal direction of the track between the metal antenna 128a and the metal antenna 128c are set to several tens of nm or more. Thereby, the interaction between the metal antennas 128a, 128b and 128c can be suppressed, and the degree of freedom of the shape of the metal antennas 128a, 128b and 128c is increased.
  • the tracking metal antennas 128b and 128c are arranged in a direction perpendicular to the track 112 with the recording or reproduction metal antenna 128a as the center.
  • the metal antennas 128b and 128c are disposed at positions separated from the metal antenna 128a by a distance P in a direction perpendicular to the track 112, respectively.
  • the distance P is a quarter of the tracking period (track pitch) Tp.
  • the distance (2P) in the direction perpendicular to the track 112 between the metal antenna 128b and the metal antenna 128c is fixed to one half of the tracking period Tp.
  • FIG. 13A is a graph showing changes in the intensity of reflected light from the metal antennas 128a, 128b, and 128c with respect to the distance from the track of the metal antennas 128a, 128b, and 128c.
  • FIG. 13B is a graph showing changes in the intensity of the detection signals te1 and te2 from the light receiving elements 120b and 120c for tracking.
  • FIG. 13C is a graph showing a change in intensity of the tracking signal TE, which is the difference between the detection signal te1 and the detection signal te2 output from the operational amplifier 111.
  • the metal antennas 128 a, 128 b and 128 c interact with the fine particles 102 and plasmon resonate together with the fine particles 102.
  • the resonance state between the metal antennas 128a, 128b, and 128c and the fine particles 102 varies depending on the design of the metal antennas 128a, 128b, and 128c and the fine particles 102. For this reason, depending on the design, the reflected light intensity from the metal antennas 128a, 128b, and 128c may increase due to plasmon resonance, or the reflected light intensity from the metal antennas 128a, 128b, and 128c may decrease due to plasmon resonance. is there. In the second embodiment, the case where the reflected light intensity from the metal antennas 128a, 128b, and 128c decreases due to resonance with the fine particles 102 is shown as an example.
  • the resonance state of plasmon resonance reacts sensitively to the distance between the metal antennas 128a, 128b and 128c and the fine particles 102. For this reason, the reflected light intensity from the metal antennas 128a, 128b and 128c is minimized at the track position (position where the distance from the track 112 coincides with the tracking period Tp) as shown in FIG. Is the maximum at a position where the distance from is half the tracking period Tp.
  • the detection signals te1 and te2 of the light receiving elements 120b and 120c are input to the operational amplifier 111 that functions as a tracking signal calculation circuit.
  • the operational amplifier 111 outputs the difference between the detection signal te1 and the detection signal te2 as the tracking signal TE.
  • the operational amplifier 111 serving as the tracking signal calculation circuit obtains the tracking signal TE based on the change in the resonance state of each of the plurality of resonance elements (metal antennas 128b and 128c).
  • the tracking metal antennas 128b and 128c are set apart from the recording or reproducing metal antenna 128a by a quarter of the tracking period Tp in the direction perpendicular to the track 112, respectively. ing. Therefore, as shown in FIGS. 13B and 13C, the difference between the detection signal te1 and the detection signal te2 can be maximized, and a highly accurate tracking signal TE can be obtained.
  • the output tracking signal TE is input to the actuator 106.
  • the actuator 106 drives the slider 124 in a direction perpendicular to the track 112 in response to the tracking signal TE.
  • the metal antennas 128b and 128c correspond to an example of a plurality of resonance elements
  • the slider 124 corresponds to an example of a holding element
  • the light receiving elements 120b and 120c include the first detection element and the plurality of resonance elements.
  • the suspension 125 corresponds to an example of a light receiving element
  • the suspension 125 corresponds to an example of a second moving element
  • the waveguides 129b and 129c correspond to an example of a plurality of waveguides.
  • the slider 124 can scan the disk 101 at a position of several nm to several tens of nm on the disk 101 without the slider 124 and the disk 101 coming into contact with each other. Therefore, precise gap control can be performed without causing the disk 101 and the slider 124 to wear.
  • the metal antennas 128a, 128b, and 128c are arranged so as to be shifted in the longitudinal direction of the track. That is, the slider 124 is arranged by shifting the positions of the metal antennas 128b and 128c in the longitudinal direction of the track. Thereby, the interaction between the adjacent metal antennas 128a, 128b, and 128c can be suppressed, and the degree of freedom of the shape of the metal antennas 128a, 128b, and 128c is increased.
  • the polarization direction of incident light incident on the plurality of resonant elements (metal antennas 128 b and 128 c) from the light source (semiconductor laser elements 107 b and 107 c) is a direction perpendicular to the surface of the disk 101.
  • the longitudinal position of the track of the plurality of resonance elements (metal antenna 128b and metal antenna 128c) is the thickness in the longitudinal direction of the track of one resonance element of the plurality of resonance elements (metal antenna 128b or 128c). It may be shifted as described above. Thereby, the interaction between a plurality of resonant elements can be further suppressed.
  • reflected light is detected instead of near-field light. This eliminates the need to fabricate minute light receiving elements 110a, 110b, and 110c in the immediate vicinity of the metal antennas 128a, 128b, and 128c, and facilitates fabrication of the optical information device.
  • the light receiving elements 120a, 120b, and 120c do not interact with the metal antennas 128a, 128b, and 128c. For this reason, the metal antennas 128a, 128b, and 128c and the disk 101 can be efficiently interacted, and tracking and information recording or reproduction can be performed efficiently.
  • a pair of a semiconductor laser element and a light receiving element is disposed adjacent to one waveguide, but for example, a Y-shaped waveguide may be used.
  • a semiconductor laser element may be disposed on one side of the Y-shaped waveguide, and a light receiving element may be disposed on the other side.
  • a stepped step is formed on the end surface of the slider 124, and the metal antennas 128a, 128b, and 128c are arranged on each step.
  • the metal antennas 128a, 128b, and 128c only need to be shifted in the longitudinal direction of the track so as not to interact with each other.
  • FIG. 14 is a top view showing the slider in the first modification of the second embodiment of the present invention
  • FIG. 15 is a top view showing the slider in the second modification of the second embodiment of the present invention. is there.
  • the end surface of the slider 124 may be convex or concave.
  • the metal antennas 128a, 128b and 128c are arranged so as to be shifted in the longitudinal direction of the track.
  • the slider 124 and the air slider 132 are configured separately, but the present invention is not particularly limited to this, and the slider 124 may be enlarged.
  • the slider 124 may also have the function of an air slider that moves the slider 124 in a direction perpendicular to the surface of the disk 101. Also in this case, the gist of the present invention is not impaired.
  • FIG. 16 is a diagram showing a configuration of a slider in a modification of the first and second embodiments of the present invention.
  • the optical information apparatus includes a motor 116 instead of the actuator 106 according to the first and second embodiments.
  • the motor 116 rotates the suspension 105 (125) around the motor 116 in a plane parallel to the surface of the disk 101.
  • the motor 116 may rotate the suspension 105 (or 125) as an arm and drive the slider 104 (or 124) in a direction perpendicular to the track like a hard disk drive.
  • Embodiments 1 and 2 fine particles composed of a phase change material are used for recording or reproducing information, but the present invention is not particularly limited to this.
  • the optical information device is an optical information device that performs only reproduction, such as a ROM (Read Only Memory) device, for example, an uneven pit may be used instead of fine particles, or a metal pattern or the like may be used. Also good.
  • the shape of the metal antenna is a triangular plate shape.
  • the shape of the metal antenna is not particularly limited to the above example, and examples other than the triangular plate shape are shown in FIGS. Such a shape is also conceivable.
  • the shape of the metal antenna is not particularly limited as long as plasmon resonance occurs on the fine particles and the plasmon resonance state efficiently changes according to the distance from the track.
  • FIG. 17 is a diagram showing a metal antenna having a square plate shape in the first and second embodiments of the present invention
  • FIG. 18 is a metal antenna having a disk shape in the first and second embodiments of the present invention
  • FIG. 19 is a diagram showing a metal antenna having a probe shape in the first and second embodiments of the present invention.
  • the metal antenna 117 when the shape of the metal antenna 117 is a rectangular flat plate shape, the metal antenna 117 is vertically symmetric, so that the analysis is easier than the triangular flat plate shape. Further, as shown in FIG. 18, when the shape of the metal antenna 118 is a disc shape, the pattern can be easily produced as compared with the triangular plate shape. Further, as shown in FIG. 19, when the shape of the metal antenna 119 is a probe shape, near-field light can be generated more efficiently at the tip of the probe.
  • the two metal antennas are arranged so as to be shifted by a half of the tracking period Tp in a direction perpendicular to the track.
  • the number of metal antennas and the arrangement method are such that the difference in detection signals from a plurality of metal antennas for tracking is zero at the track position and the difference in detection signals can be obtained according to the positional deviation from the track. Good.
  • the number of metal antennas for tracking and the arrangement method are not particularly limited to the configurations shown as the first and second embodiments.
  • the plurality of waveguides 109a to 109c are arranged non-parallel to each other in order to suppress the waveguide mode coupling. However, the waveguide mode coupling does not occur. If so, the plurality of waveguides 109a to 109c (129a to 129c) may be arranged in parallel to each other, and this does not impair the gist of the present invention.
  • the semiconductor laser elements 107a to 107c, the metal antennas 108a to 108c (128a to 128c), and the light receiving elements 110a to 110c (120a to 120c) are disposed on the end face of the slider 104 (124).
  • the present invention is not particularly limited to this. These elements may be arranged on the upper surface of the slider 104 (124) or inside the slider 104 (124), or these elements may be integrated on a single chip.
  • the optical information device includes three light sources (semiconductor laser elements 107a to 107c).
  • the optical information device includes one light source and emits light from one light source. The light may be incident on the metal antenna after being separated in three directions by a waveguide.
  • the optical information device includes one light source for recording or reproduction and one light source for tracking, and separates light from only the light source for tracking in two directions by a Y-shaped waveguide, thereby providing two metal antennas. Light may be incident on. These do not impair the gist of the present invention.
  • FIG. 20 is a schematic diagram showing the configuration of the optical information device according to the third embodiment of the present invention.
  • 21 is a perspective view showing the configuration of the plurality of metal antennas shown in FIG. 20, and
  • FIG. 22 is a top view showing the configuration of the plurality of metal antennas shown in FIG. 20 to 22, the same components as those in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof is omitted.
  • the optical information device includes semiconductor laser elements 202a, 202b, 202c, 202d, metal antennas 228a, 228b, 228c, lenses 203, 204, 205, 206, 207, half mirrors 208, 209, dichroic mirrors 210, 4 A half-wave plate 211, an analyzer 212, a light shielding plate 213, a diffraction grating 214, light receiving elements 215a, 215b, 215c, and 215d, a solid immersion lens 216, a lens holder 217, an actuator 218, and an operational amplifier 111 are provided.
  • a disk 221 is an information recording medium having tracks on which information is recorded in a line.
  • a groove 201 functioning as a track is formed on the disk 221, and information is recorded on the groove 201.
  • the output wavelengths of the semiconductor laser elements 202a, 202b, 202c and 202d are different from each other.
  • the semiconductor laser elements 202a, 202b, 202c, and 202d emit light having wavelengths of 780 nm, 630 nm, 830 nm, and 400 nm, respectively.
  • the polarization of light from the semiconductor laser elements 202a, 202b, 202c and 202d is linearly polarized light.
  • the semiconductor laser element 202a is used as a light source for recording or reproducing information
  • the semiconductor laser elements 202b and 202c are used as light sources for tracking
  • the semiconductor laser element 202d is used as a light source for gap detection.
  • the metal antennas 228a, 228b, and 228c are resonance elements that excite plasmon resonance by light from the semiconductor laser elements 202a, 202b, and 202c, respectively.
  • the metal antennas 228a, 228b, and 228c are made of a material such as gold, silver, copper, titanium, aluminum, or chromium. Further, as shown in FIG. 21, the metal antennas 228a, 228b, and 228c have a triangular flat plate shape.
  • the metal antennas 228 a, 228 b, and 228 c are arranged so that the triangular surface is parallel to the surface of the disk 221.
  • the metal antennas 228b and 228c which are resonance elements, interact with the disk 221, and the resonance state changes according to the distance from the track (groove 201).
  • the metal antennas 228a, 228b and 228c have different shapes or materials so that the maximum plasmon resonance can be obtained on the track center with respect to the light emitted from the semiconductor laser elements 202a, 202b and 202c, respectively.
  • the tracking metal antennas 228b and 228c are arranged with their positions shifted in the direction perpendicular to the track with the recording or reproduction metal antenna 228a as the center.
  • the metal antennas 228b and 228c are disposed at positions separated from the metal antenna 228a by a distance P in a direction perpendicular to the track 112, respectively.
  • the distance P is a quarter of the tracking period (track pitch) Tp.
  • the distance (2P) in the direction perpendicular to the track between the metal antenna 228b and the metal antenna 228c is fixed to one half of the tracking period Tp.
  • the metal antennas 228a and 228b are arranged so that the apex of the metal antenna 228a and the base of the metal antenna 228b do not overlap with the longitudinal direction of the track in order to avoid a plurality of metal antennas from interacting with each other. It is arranged to shift to.
  • the metal antennas 228a and 228c are arranged so as to be shifted in the longitudinal direction of the track so that the bottom of the metal antenna 228a and the apex of the metal antenna 228c do not overlap with the longitudinal direction of the track.
  • the polarization directions of the semiconductor laser elements 202a, 202b, and 202c are made to coincide with the resonance directions of the metal antennas 228a, 228b, and 228c that function as resonance elements having different resonance frequencies.
  • the polarization direction of incident light incident on the plurality of resonance elements (metal antennas 228b and 228c) from the light source (semiconductor laser elements 202b and 202c) is the disk 221.
  • the position in the longitudinal direction of the track between the plurality of resonance elements (metal antennas 228b and 228c) is shifted more than the length in the longitudinal direction of the track of one resonance element of the plurality of resonance elements.
  • the dichroic mirror 210 reflects light having a wavelength of 500 nm or less.
  • the quarter-wave plate 211 converts linearly polarized light into circularly polarized light with respect to the light from the semiconductor laser element 202d.
  • the analyzer 212 transmits light having the same polarization direction as that of the light from the semiconductor laser element 202d.
  • the light shielding plate 213 shields light at the central portion and transmits only light at the peripheral portion.
  • the diffraction grating 214 diffracts the reflected light from the metal antenna 228a to the light receiving element 215a, diffracts the reflected light from the metal antenna 228b to the light receiving element 215b, and diffracts the reflected light from the metal antenna 228c to the light receiving element 215c.
  • the light receiving elements 215a, 215b, and 215c individually detect changes in the resonance states of the metal antennas 228a, 228b, and 228c, and output detection signals.
  • the light receiving elements 215a, 215b and 215c individually detect scattered light from the metal antennas 228a, 228b and 228c, respectively.
  • the light receiving element 215d detects the distance between the metal antennas 228a, 228b and 228c and the disk 221.
  • the light receiving element 215d outputs a gap signal GT indicating the distance between the metal antennas 228a, 228b, and 228c and the disk 221.
  • Metal antennas 228a, 228b and 228c are formed on the bottom surface of the solid immersion lens 216.
  • the solid immersion lens 216 functions as a holding element that holds the metal antennas 228a, 228b, and 228c.
  • the solid immersion lens 216 which is a holding element, is arranged by shifting the positions of a plurality of resonance elements (metal antennas 228b and 228c) in a direction perpendicular to the track and fixing the distance between the plurality of resonance elements constant. Hold.
  • the lens holder 217 holds the solid immersion lens 216 and the lens 207, and relatively fixes the positions of the solid immersion lens 216 and the lens 207.
  • the actuator 218 moves the lens holder 217 in the direction perpendicular to the track and the direction perpendicular to the surface of the disk 221 based on the gap signal GT output from the light receiving element 215d and the tracking signal TE output from the operational amplifier 111. That is, the actuator 218 as the first moving element moves the holding element (solid immersion lens 216) in a direction perpendicular to the track in accordance with the tracking signal TE.
  • the actuator 218 has a plurality of resonance elements (metal antennas 228b and 228c) and a plurality of the plurality of resonance elements (metal antennas 228b and 228c) so that the distance between the disk 221 is constant according to the detection signal (gap signal GT) from the light receiving element 215d.
  • the resonant elements (metal antennas 228b and 228c) are moved in a direction perpendicular to the surface of the disk 221.
  • the lens 204, the half mirror 209, the lens 207, and the like are optical elements that guide light from the light sources (semiconductor laser elements 202b and 202c) to a plurality of resonance elements (metal antennas 228b and 228c). Function.
  • the disk 221 corresponds to an example of an information recording medium
  • the semiconductor laser elements 202b and 202c correspond to examples of a light source and a plurality of light sources
  • the metal antennas 228b and 228c include a plurality of resonance elements.
  • the solid immersion lens 216 corresponds to an example of a holding element
  • the light receiving elements 215b and 215c correspond to an example of a first detection element and a plurality of light receiving elements
  • the actuator 218 corresponds to an example of a first moving element and a first moving element.
  • the light receiving element 215d corresponds to an example of a second detection element
  • the diffraction grating 214 corresponds to an example of an optical element.
  • the operation of the optical information apparatus in the third embodiment will be described.
  • the gap detection method of the optical information device in the third embodiment will be described.
  • the light emitted from the semiconductor laser element 202d is collimated by the lens 203 and passes through the half mirror 208.
  • the light transmitted through the half mirror 208 is converted into circularly polarized light by the quarter wave plate 211 and reflected by the dichroic mirror 210.
  • the light reflected by the dichroic mirror 210 is collected by the lens 207 and the solid immersion lens 216.
  • the component light having a high numerical aperture NA is totally reflected on the bottom surface of the solid immersion lens 216.
  • the light totally reflected by the bottom surface of the solid immersion lens 216 is transmitted through the lens 207, is reflected by the dichroic mirror 210, and is transmitted through the quarter-wave plate 211 again.
  • Totally reflected light is out of phase with polarized light perpendicular to the reflecting surface and polarized light parallel to the reflecting surface as compared to before total reflection. Therefore, the light transmitted through the quarter-wave plate 211 again includes light having the same polarization as the light emitted from the semiconductor laser element 202d.
  • the light transmitted through the quarter-wave plate 211 is reflected by the half mirror 208, and only the light having the same polarization as that emitted from the semiconductor laser element 202 d is transmitted by the analyzer 212, and condensed by the lens 205 onto the light receiving element 215 d. Is done.
  • the light receiving element 215 d generates a gap signal GT by detecting the intensity of light totally reflected on the bottom surface of the solid immersion lens 216, and outputs the gap signal GT to the actuator 218.
  • the actuator 218 performs gap control based on the input gap signal GT.
  • the actuator 218 moves the plurality of resonance elements (metal antennas 228b and 228c) in a direction perpendicular to the surface of the disk 221.
  • the actuator 218 has a second detection element (light receiving element 215d) that detects the distance between the plurality of resonance elements (metal antennas 228b and 228c) and the disk 221. ),
  • the plurality of resonance elements (metal antennas 228b and 228c) are placed on the disk 221 so that the distance between the plurality of resonance elements (metal antennas 228b and 228c) and the disk 221 is constant. Move in a direction perpendicular to the surface.
  • the light emitted from the semiconductor laser elements 202a, 202b and 202c is collimated by the lens 204 and reflected by the half mirror 209.
  • the light reflected by the half mirror 209 passes through the dichroic mirror 210 and is collected by the lens 207 and the solid immersion lens 216.
  • the condensed light is incident on metal antennas 228a, 228b, and 228c formed on the bottom surface of the solid immersion lens 216, and excites plasmon resonance in the corresponding metal antennas 228a, 228b, and 228c. Each excited plasmon resonance generates scattered light having a corresponding wavelength.
  • the scattered light is collimated by the solid immersion lens 216 and the lens 207 and passes through the dichroic mirror 210.
  • the scattered light that has passed through the dichroic mirror 210 passes through the light shielding plate 213 after passing through the half mirror 209.
  • the central portion of the light shielding plate 213 is shielded from light, and only the scattered light forming the peripheral portion is transmitted by shielding the central portion light including the reflected incident light.
  • the scattered light transmitted through the light shielding plate 213 is diffracted by the diffraction grating 214 at different angles for each wavelength, and is condensed by the lens 206 onto the corresponding light receiving elements 215a, 215b, and 215c.
  • the light receiving elements 215a, 215b, and 215c detect scattered light from the metal antennas 228a, 228b, and 228c.
  • the light source includes a plurality of light sources (semiconductor laser elements 202b and 202c) that emit light having different wavelengths.
  • the plurality of resonance elements (metal antennas 228b and 228c) are formed in a shape or material having the resonance frequency as the frequency of light emitted from each of the plurality of light sources (semiconductor laser elements 202b and 202c).
  • the first detection element that individually detects and outputs the change in the resonance state of each of the plurality of resonance elements (metal antennas 228b and 228c) includes the plurality of light receiving elements 215b and 215c and the plurality of resonance elements.
  • an optical element (diffraction grating 214) that separates the plurality of lights having different frequencies and guides each of the plurality of lights to the corresponding light receiving elements 215b and 215c.
  • FIG. 23A is a graph showing changes in scattered light intensity from the metal antennas 228a, 228b and 228c with respect to the distance from the track of the metal antennas 228a, 228b and 228c.
  • FIG. 23B is a graph showing intensity changes of the detection signals te1 and te2 from the tracking light receiving elements 215b and 215c.
  • FIG. 23C is a graph showing a change in intensity of the tracking signal TE output from the operational amplifier 111.
  • the scattered light intensity from the metal antennas 228a, 228b, and 228c becomes maximum at the track position (position where the distance from the groove 201 coincides with the tracking period Tp), and the track (groove 201). Is the minimum at a position where the distance from is half the tracking period Tp.
  • the detection signal of the light receiving element 215a is used as a reproduction signal.
  • the detection signals te1 and te2 of the light receiving elements 215b and 215c change as shown in FIG. 23B and are input to the operational amplifier 111 that functions as a tracking signal arithmetic circuit.
  • the operational amplifier 111 outputs the difference between the detection signal te1 and the detection signal te2 with respect to the distance from the track as a tracking signal TE as shown in FIG.
  • the operational amplifier 111 serving as the tracking signal calculation circuit calculates the tracking signal TE based on the change in the resonance state of each of the plurality of resonance elements (metal antennas 228b and 228c).
  • the tracking metal antennas 228b and 228c are set apart from the recording or reproduction metal antenna 228a by a quarter of the tracking period Tp in the direction perpendicular to the track. Yes. Therefore, the difference between the detection signal te1 and the detection signal te2 can be maximized, and a highly accurate tracking signal TE can be obtained.
  • the individual resonance states of the metal antennas 228a, 228b, and 228c are detected using the difference in wavelength. For this reason, it is not necessary to integrate the light source, the first detection element, the waveguide, and the plurality of resonance elements in a minute region, and the production of the optical information device is easy.
  • the metal antennas 228a, 228b, and 228c are arranged so as to be parallel to the surface of the disk 221, and plasmon resonance is performed by incident light having a polarization direction parallel to the surface of the disk 221. Excited. For this reason, it is not necessary to hold the metal antennas 228a, 228b, and 228c perpendicular to the surface of the disk 221, and the manufacturing is easy.
  • the groove 201 is formed on the disk 221. Therefore, a large tracking signal can be obtained as compared with an information recording medium in which fine particles are arranged.
  • gap control is performed by detecting a change in the intensity of reflected light. For this reason, the application from the technique used in the conventional optical pickup is easy, and at the same time, the application to a removable information recording medium is also possible.
  • a disk having a groove is used as the information recording medium.
  • the fine particles arranged in rows used in the first and second embodiments may be used. good.
  • the shape of the metal antenna is a triangular plate shape.
  • the shape of the metal antenna is not particularly limited to the above example, and for example, as shown in FIGS. It may be a simple shape.
  • the shape of the metal antenna is not particularly limited as long as plasmon resonance occurs on the track and the plasmon resonance state efficiently changes according to the distance from the track.
  • FIG. 24 is a diagram showing a fan-shaped metal antenna in Embodiment 3 of the present invention
  • FIG. 25 is a diagram showing a bow-tie metal antenna in Embodiment 3 of the present invention.
  • FIG. 26 is a diagram showing a metal antenna having a nanobeak shape in the third embodiment of the present invention.
  • the shape of the metal antenna 117 when the shape of the metal antenna 117 is a fan shape, the influence of the parasitic light at the bottom side portion is reduced as compared with the triangular plate shape.
  • the shape of the metal antenna 117 when the shape of the metal antenna 117 is a bow tie shape, near-field light can be generated more efficiently in the portion where the apexes of the metal antenna face each other than the triangular plate shape.
  • the near-field light can be condensed three-dimensionally and the near-field light can be generated efficiently.
  • the recording or reproducing metal antenna 228a is disposed between the two tracking metal antennas 228b and 228c in the longitudinal direction of the track.
  • the present invention is particularly limited to this. Instead, the arrangement shown in FIGS. 27 to 29 may be used.
  • FIG. 27 is a diagram showing an example in which the tracking metal antenna is arranged close to the third embodiment of the present invention
  • FIG. 28 shows the direction of the tracking metal antenna in the third embodiment of the present invention
  • FIG. 29 is a diagram showing an example of disposing differently, and FIG. 29 is an example of disposing the recording or reproducing metal antenna and the tracking metal antenna so that the directions thereof are orthogonal to each other in the third embodiment of the present invention.
  • the recording or reproducing metal antenna 228a may be arranged independently, and the tracking metal antennas 228b and 228c may be arranged so as to approach each other.
  • the tracking accuracy is improved.
  • the tracking metal antennas 228b and 228c are all arranged in the same direction. However, as shown in FIG. 28, the tracking metal antennas 228b and 228c are oriented in the longitudinal direction of the track. The tracking metal antennas 228b and 228c may be arranged so that the positions of the vertices in the longitudinal direction of the tracks approach each other. In the configuration shown in FIG. 28, the tracking metal antennas 228b and 228c have the same detection position in the longitudinal direction of the track, so that tracking accuracy is improved.
  • the resonance states of the metal antennas 228b and 228c are separated using the difference in the wavelength of the scattered light.
  • the recording or reproducing metal antenna 228a and the tracking are separated.
  • the metal antennas 228b and 228c may be arranged so that their directions are orthogonal to each other. That is, the tracking metal antennas 228b and 228c are arranged so as to face each other in the direction perpendicular to the track, and the scattered light of the recording or reproducing metal antenna 228a and the scattered light of the tracking metal antennas 228b and 228c May be separated using a difference in polarization direction. If the configuration as shown in FIG. 29 is used, the number of light sources that emit light having different wavelengths can be reduced.
  • the main configuration of the optical information apparatus described in the first embodiment, the second embodiment, and the third embodiment is described below.
  • the optical information device described in the first embodiment, the second embodiment, and the third embodiment is an optical information device that records or reproduces information on an information recording medium having a track, and includes a light source and light from the light source.
  • a holding element that holds the distance between the resonance elements fixed at a fixed level, a first detection element that individually detects a change in the resonance state of each of the plurality of resonance elements, and a resonance detected by the first detection element
  • a tracking signal calculation circuit that calculates a tracking signal based on a change in state, and a holding element is moved in a direction perpendicular to the track according to the tracking signal calculated by the tracking signal calculation circuit.
  • a a first moving element to be.
  • the positions of the plurality of resonance elements whose resonance states change according to the distance from the track are shifted in the direction perpendicular to the track, and the distances between the plurality of resonance elements are fixedly held. Is done.
  • the relative position between the plurality of resonance elements and the information recording position on the track does not change due to the interaction. For this reason, a stable and highly accurate tracking signal depending only on the displacement from the track position can be obtained.
  • the resonance state is sensitive to changes in the optical constants around the resonance element. For this reason, even if the information recording state on the track is an information recording state not accompanied by a change in surface shape, tracking can be performed stably and with high accuracy.
  • the change in the resonance state of the plurality of resonance elements is individually detected by the plurality of light receiving elements, and the difference between the detection signals is output as a tracking signal.
  • the detection signal reacts sensitively to changes in the optical constants around the resonant element, and a tracking signal having a high degree of modulation with respect to a positional deviation from a minute track can be obtained. For this reason, a stable and highly accurate tracking signal can be obtained.
  • FIG. 30 is a schematic diagram showing the configuration of the optical information apparatus in the fourth embodiment of the present invention
  • FIG. 31 is a top view showing the configuration of the optical information apparatus in the fourth embodiment of the present invention
  • 32 is a perspective view showing the configuration of the slider shown in FIG. 30
  • FIG. 33 is a side view showing the configuration of the slider shown in FIG. 30,
  • FIG. 34 is a top view showing the configuration of the slider shown in FIG. FIG. 30 to 34, the same components as those in FIGS. 1 to 4 and FIGS. 9 to 12 are denoted by the same reference numerals, and description thereof is omitted.
  • the optical information device includes semiconductor laser elements 107a, 107b, 107c, metal antennas 128a, 128b, 128c, waveguides 129a, 129b, 129c, light receiving elements 120a, 120b, 120c, a motor 103, an air slider. 132, a slider 141, a suspension 142, a motor 143, piezo elements 144a and 144b, a yawing signal calculation circuit 151, and a tracking signal calculation circuit 161.
  • a disk 101 having fine particles 102 arranged in a track shape is fixed and held by a motor 103.
  • the slider 141 as a holding element is arranged by shifting the positions of the metal antennas 128a, 128b and 128c as resonance elements in the direction perpendicular to the track 112, and the distance between the metal antennas 128a, 128b and 128c is fixed. And hold.
  • Metal antennas 128a, 128b, and 128c which are resonance elements, receive light from semiconductor laser elements 107b and 107c, interact with disk 101, and the resonance state changes according to the distance from track 112.
  • the metal antennas 128a, 128b, and 128c in the fourth embodiment are made of a material such as gold, silver, copper, titanium, aluminum, or chromium.
  • the metal antennas 128a, 128b, and 128c are triangular flat plate shapes.
  • the metal antennas 128a, 128b, and 128c are arranged so that one vertex of the triangle is closest to the surface of the fine particle 102, and strong near-field light is generated near the vertex of the triangle when plasmon resonance is excited.
  • the distance between the metal antennas 128a, 128b, and 128c in the fourth embodiment and the surface of the fine particles 102 is preferably several tens of nm or less. More preferably, it is nm.
  • the distance P1 between the metal antenna 128a and the metal antenna 128b is larger than the distance P2 between the metal antenna 128a and the metal antenna 128c.
  • the metal antennas 128a, 128b, and 128c interact with the microparticles 102 and plasmon resonate together.
  • the resonance state between the metal antennas 128a, 128b, and 128c and the fine particles 102 varies depending on the design of the metal antennas 128a, 128b, and 128c and the fine particles 102.
  • the reflected light intensity from the metal antennas 128a, 128b, and 128c may increase due to plasmon resonance, or the reflected light intensity from the metal antennas 128a, 128b, and 128c may decrease due to plasmon resonance. is there.
  • the fourth embodiment the case where the reflected light intensity from the metal antennas 128a, 128b, and 128c decreases due to resonance with the fine particles 102 is shown as an example.
  • the resonance state of plasmon resonance reacts sensitively to the distance between the metal antennas 128a, 128b and 128c and the fine particles 102. Therefore, the reflected light intensity from the metal antennas 128a, 128b, and 128c is the track position (position where the distance from the track 112 coincides with the tracking period Tp) as shown in FIG. 13A of the second embodiment. It becomes the minimum and becomes the maximum at the position where the distance from the track 112 becomes half of the tracking period Tp.
  • the air slider 132 moves the metal antennas 128a, 128b, and 128c in a direction perpendicular to the surface of the disk 101.
  • the suspension 142 is composed of a spring element.
  • the slider 141 and the air slider 132 are held facing the disk 101 by a suspension 142.
  • the distance between the slider 141 and the disk 101 is kept constant by using a technique similar to that of a flying head employed in a hard disk drive.
  • the second moving element that moves the plurality of resonant elements in the direction perpendicular to the surface of the information recording medium includes the suspension 125 (spring element). Yes.
  • the suspension 125 keeps the distance between the disk 101, the slider 104, and the air slider 132 constant by the force of the airflow flowing between the slider 104 and the air slider 132 and the disk 101.
  • the suspension 142 is rotated by a motor 143.
  • the motor 143 as the first moving element moves the holding element (slider 141) in a direction perpendicular to the track 112 in accordance with the tracking signal.
  • the slider 141 scans the disk 101.
  • the yawing signal calculation circuit 151 calculates a yawing signal that represents the inclination of the slider 141 in a plane parallel to the surface of the disk 101 based on the change in the resonance state detected by the light receiving elements 120b and 120c.
  • the yawing signal calculation circuit 151 generates a yawing signal based on the detection signals te1 and te2 representing changes in the resonance state of the metal antennas 128b and 128c.
  • the piezo elements 144a and 144b are incorporated in the suspension 142.
  • the piezo elements 144 a and 144 b expand and contract in opposite phases to rotate the slider 141 in a plane parallel to the surface of the disk 101.
  • Piezo elements 144a and 144b which are rotating elements, rotate the slider 141 in a plane parallel to the surface of the disk 101 according to the yawing signal, and keep the relative distance in the direction perpendicular to the tracks of the metal antennas 128b and 128c constant. .
  • the sum of the length of the perpendicular line extending from the metal antenna 128b to the line passing through the center of the track and the length of the perpendicular line extending from the metal antenna 128c to the line passing through the center of the track is constant.
  • the slider 141 is rotated in a plane parallel to the surface of the disk 101.
  • the tracking signal calculation circuit 161 calculates a correction value for correcting the positional deviation of the track from the track from the metal antenna 128b based on the plurality of detection signals, and the plurality of detection signals corrected based on the calculated correction value. Is calculated as a tracking signal.
  • the tracking signal calculation circuit 161 generates a tracking signal based on the detection signals te0, te1, and te2 representing changes in the resonance state of the metal antennas 128a, 128b, and 128c.
  • the motor 143 moves the slider 141 in a direction perpendicular to the track 112 in accordance with the tracking signal.
  • the slider 141 has a stepped step in the direction perpendicular to the track 112 on the end face in the longitudinal direction of the track.
  • the step-like end face has three faces whose positions are different in the longitudinal direction of the track.
  • the waveguides 129a, 129b and 129c individually guide light from the semiconductor laser elements 107a, 107b and 107c to the metal antennas 128a, 128b and 128c.
  • the waveguides 129a, 129b and 129c individually guide the reflected light from the metal antennas 128a, 128b and 128c to the light receiving elements 120a, 120b and 120c.
  • the light receiving elements 120a, 120b and 120c are arranged in the vicinity of the semiconductor laser elements 107a, 107b and 107c, respectively.
  • the light receiving elements 120a, 120b, and 120c individually detect changes in the resonance states of the metal antennas 128a, 128b, and 128c.
  • Each of the light receiving elements 120a, 120b, and 120c is attached to each of the plurality of waveguides 129a, 129b, and 129c, and individually detects the reflected light from the metal antennas 128a, 128b, and 128c.
  • the first detection elements that individually detect and output changes in the resonance states of the plurality of resonance elements are the plurality of light receiving elements 120a and 120b.
  • the optical information device includes a plurality of waveguides 129a, 129b, and 129c that guide light from the plurality of resonance elements to the plurality of light receiving elements.
  • a total of three metal antennas 128a, 128b, and 128c are fixed to the stepped end face of the slider 141, one each. Plasmon resonance is excited by light from the semiconductor laser elements 107a, 107b, and 107c guided by the plurality of waveguides 129a, 129b, and 129c.
  • the interaction between two metal particles appears prominently when the distance between the metal particles is several tens of nanometers or less (Confined plasmas in nanofabricated partialspars: experiential severinstrands. Al., J. Phys. Chem. B, 2005, 109, 1079-1087). Therefore, the length L in the longitudinal direction of the track between the metal antenna 128a and the metal antenna 128b and the length L in the longitudinal direction of the track between the metal antenna 128a and the metal antenna 128c are set to several tens of nm or more. Thereby, the interaction between the metal antennas 128a, 128b and 128c can be suppressed, and the degree of freedom of the shape of the metal antennas 128a, 128b and 128c is increased.
  • the tracking metal antennas 128b and 128c are arranged in a direction perpendicular to the track with the recording or reproduction metal antenna 128a as the center.
  • the metal antennas 128b and 128c are arranged at positions separated from the metal antenna 128a by arbitrary distances P1 and P2 in a direction perpendicular to the track 112, respectively.
  • FIG. 35 is a diagram showing the configuration of the yawing signal calculation circuit 151 shown in FIG.
  • the yawing signal operation circuit 151 includes a phase comparison circuit 152, a first control circuit 153, a first sampling hold circuit 154a, a second sampling hold circuit 154b, a first addition circuit 155a, a second addition circuit 155b, and a difference.
  • a circuit 156, a second control circuit 157, and a switch 158 are provided.
  • FIG. 35 shows a positional shift between the tip position 171b of the metal antenna 128b and the tip position 171c of the metal antenna 128c when the tip position 171a of the metal antenna 128a is on the center of the track.
  • the detection signals te1 and te2 are described as being output from the tip position 171b of the metal antenna 128b and the tip position 171c of the metal antenna 128c. Are output from the light receiving elements 120b and 120c.
  • the phase comparison circuit 152 compares the phases of the detection signals te1 and te2, and outputs the phase difference between the detection signals te1 and te2 as the first yawing signal YE1.
  • the first control circuit 153 outputs a signal for driving the piezo elements 144a and 144b so that the first yawing signal YE1 becomes ⁇ radians.
  • the first sample and hold circuit 154a stores and outputs the value of the detection signal te1 when yawing signal YE1 becomes ⁇ radians as an initial value te1 0.
  • the second sample and hold circuit 154b and outputs the stored value of the detection signal te2 when yawing signal YE1 becomes ⁇ radians as an initial value te2 0.
  • the first addition circuit 155a calculates and outputs the sum of the initial value te1 0 and the initial value te2 0 .
  • the second addition circuit 155b calculates and outputs the sum of the detection signal te1 and the detection signal te2.
  • the difference circuit 156 subtracts the addition value (te1 0 + te2 0 ) of the initial value te1 0 and the initial value te2 0 from the addition value (te1 + te2) of the detection signal te1 and the detection signal te2, and outputs the result as the yawing signal YE2. .
  • the second control circuit 157 drives the piezo elements 144a and 144b according to the yawing signal YE2 so that the distance in the direction perpendicular to the track between the metal antennas 128b and 128c is maintained at half of the tracking period Tp.
  • a drive signal is output.
  • the switch 158 switches the connection destination of the piezo elements 144a and 144b to either the first control circuit 153 or the second control circuit 157.
  • the control sequence using the yawing signal is a first control that uses the yawing signal YE1 to adjust the inclination of the slider 141 so that the distance between the metal antennas 128a and 128b in the direction perpendicular to the track is half the tracking period Tp. And a second step of maintaining the tilt of the slider 141 so that the distance in the direction perpendicular to the track between the metal antennas 128a and 128b becomes half the tracking period Tp using the yawing signal YE2.
  • the motor 143 scans the slider 141 in a small amount in the direction perpendicular to the track.
  • the detection signals te1 and te2 corresponding to the resonance intensities of the metal antennas 128b and 128c periodically change with respect to the distance from the track 112, as shown in FIG.
  • the detection signals te1 and te2 are input to the phase comparison circuit 152.
  • the phase comparison circuit 152 compares the phase of the detection signal te1 with the phase of the detection signal te2, and outputs the phase difference between the two detection signals as the yawing signal YE1.
  • the first control circuit 153 outputs a drive signal for driving the piezo elements 144a and 144b so that the yawing signal YE1 output from the phase comparison circuit 152 becomes ⁇ radians.
  • the switch 158 connects the first control circuit 153 and the piezo elements 144a and 144b.
  • the motor 143 scans in the direction perpendicular to the track of the slider 141.
  • the first sample and hold circuit 154a samples the value of the detection signal te1 when yawing signal YE1 becomes ⁇ radians, is stored as an initial value te1 0.
  • the second sample and hold circuit 154b samples the value of the detection signal te2 when yawing signal YE1 becomes ⁇ radians, is stored as an initial value te2 0.
  • the first sample and hold circuit 154a outputs an initial value te1 0 of the detection signal te1
  • the second sample and hold circuit 154b sets the initial value te2 0 of the detection signal te2 Output.
  • the first addition circuit 155a adds the initial value te1 0 and the initial value te2 0 .
  • the first addition circuit 155a always outputs the sum (te1 0 + te2 0 ) of two initial values te1 0 and te2 0 as a reference value.
  • the second addition circuit 155b adds the detection signal te1 and the detection signal te2.
  • the second addition circuit 155b outputs the sum (te1 + te2) of the detection signals te1 and te2.
  • the yawing signal YE2 indicates the amount of change from the initial value of the sum of the detection signals te1 and te2.
  • the second control circuit 157 drives the piezo elements 144a and 144b according to the yawing signal YE2 so that the distance in the direction perpendicular to the track 112 between the metal antennas 128b and 128c is maintained at half of the tracking period Tp. Drive signal to output.
  • the switch 158 connects the second control circuit 157 and the piezo elements 144a and 144b.
  • the track angle changes due to the eccentricity of the disk 101 or the movement in the direction perpendicular to the track using the motor 143 and the suspension 142
  • the distance changes. That is, when the track is tilted counterclockwise about the tip position 171a of the metal antenna 128a, the distance P1 between the tip position 171b of the metal antenna 128b and the track center is increased, and the tip position of the metal antenna 128c is increased.
  • the distance P2 between 171c and the track center is increased.
  • the initial values of the detection signals te1 and te2 are te1 0 and te2 0 , respectively.
  • the phase difference of the detection signal te1 and the detection signal te2 with respect to the track position shift is ⁇ radians. It becomes a constant value (te1 0 + te2 0 ).
  • the sum (te1 0 + te2 0 ) of the initial values te1 0 and te2 0 can be used as the reference value of the yawing signal YE2 regardless of the positional deviation from the track.
  • the intensities of the detection signals te1 and te2 are values represented by white circles.
  • both the metal antennas 128b and 128c approach the track center, and the intensity of the detection signals te1 and te2 is shifted in the cw direction in FIG. It becomes the value to be. For this reason, when the track angle changes clockwise, the detection signals te1 and te2 both decrease.
  • the yawing signal YE2 is an error signal that zero-crosses at the origin. Further, the sum (te1 0 + te2 0 ) of the initial values te1 0 and te2 0 used as the reference value does not change with respect to the positional deviation from the track. For this reason, the yawing signal YE2 can be generated even when the track is off the track. By controlling the tilt of the slider 141 based on the yawing signal YE2, the distance in the direction perpendicular to the track between the metal antennas 128b and 128c can be maintained at half the tracking period Tp.
  • FIG. 40 is a conceptual diagram for explaining the track angle change in the case of P1 ⁇ P2. If the three metal antennas 128a, 128b, and 128c are not accurately aligned, an unbalanced arrangement as shown in FIG. 40 can be obtained. As shown in FIG. 40, when the track angle changes due to the eccentricity of the disk 101 or the movement in the direction perpendicular to the track using the motor 143 and the suspension 142, the direction perpendicular to the track of the metal antennas 128a, 128b and 128c. The distance changes.
  • the distance P1 between the tip position 171b of the metal antenna 128b and the track center is increased, and the tip position of the metal antenna 128c is increased.
  • the distance P2 between 171c and the track center is increased.
  • FIG. 41 is a diagram showing changes in the intensity of the detection signals te1 and te2 with respect to the positional deviation from the track when P1 ⁇ P2.
  • the initial values of the detection signals te1 and te2 are te1 0 and te2 0 , respectively.
  • the phase difference of the detection signal te1 and the detection signal te2 with respect to the track position deviation is ⁇ radians, so the average of the two detection signals ((te1 + te2) / 2) It becomes a constant value ((te1 0 + te2 0 ) / 2) regardless of the deviation.
  • the sum (te1 0 + te2 0 ) of the initial values te1 0 and te2 0 can be used as the reference value of the yawing signal YE2 regardless of the positional deviation from the track.
  • FIG. 42 is a diagram showing changes in the intensity of the detection signals te1 and te2 with respect to the distance between the track center and the tips of the metal antennas 128b and 128c when P1 ⁇ P2.
  • the strengths of the detection signals te1 and te2 are values represented by white circles.
  • the phases of the detection signals te1 and te2 with respect to changes in the track angle are shifted by the same amount in the opposite direction.
  • the sum (te1 0 + te2 0 ) of the initial values te1 0 and te2 0 used as the reference value does not change with respect to the positional deviation from the track. For this reason, the yawing signal YE2 can be generated even when the track is off the track.
  • FIG. 44 is a diagram showing the sensitivity of the yawing signal YE2 with respect to the distance between the track center and the midpoints of the tips of the metal antennas 128b and 128c when P1 ⁇ P2.
  • the sensitivity of the yawing signal YE2 to the change in the track angle when the change in the track angle is 0 changes as shown in FIG.
  • the sensitivity of the yawing signal YE2 is maximum when the track center and the midpoint of the tips of the metal antennas 128b and 128c coincide, and the distance between the track center and the midpoint of the tips of the metal antennas 128b and 128c is Tp / 4. 0.
  • the distance in the direction perpendicular to the track between the metal antennas 128b and 128c can be kept at half the tracking period Tp even when P1 ⁇ P2. .
  • the yawing signal calculation circuit 151 obtains a yawing signal based on the change in the resonance state of the resonance element.
  • the piezo elements 144a and 144b rotate the holding element (slider 141) in a plane parallel to the surface of the information recording medium according to the yawing signal.
  • the tracking signal calculation circuit 161 includes a correction value calculation circuit 162, a first difference circuit 163a, a second difference circuit 163b, a weighted difference circuit 164, and a control circuit 165.
  • FIG. 45 shows a positional shift between the tip position 171b of the metal antenna 128b and the tip position 171c of the metal antenna 128c when the tip position 171a of the metal antenna 128a is on the center of the track.
  • the detection signals te0, te1, and te2 are output from the tip position 171a of the metal antenna 128a, the tip position 171b of the metal antenna 128b, and the tip position 171c of the metal antenna 128c.
  • the detection signals te0, te1, and te2 are output from the light receiving elements 120a, 120b, and 120c.
  • the motor 143 scans the slider 141 in a direction perpendicular to the track.
  • the detection signals te0, te1, and te2 corresponding to the resonance intensities of the metal antennas 128a, 128b, and 128c periodically change with respect to the distance from the track, as shown in FIG.
  • the detection signals te0, te1 and te2 are input to the correction value calculation circuit 162.
  • the correction value calculation circuit 162 determines correction values a and b based on the detection signals te0, te1, and te2. A method for determining the correction values a and b will be described later.
  • the motor 143 stops scanning the slider 141 in the direction perpendicular to the track.
  • the first difference circuit 163a generates a difference (te1-te0) between the detection signal te1 and the detection signal te0 and outputs the difference to the weighted difference circuit 164.
  • the second difference circuit 163b generates a difference (te2 ⁇ te0) between the detection signal te2 and the detection signal te0 and outputs the difference to the weighted difference circuit 164.
  • the weighted difference circuit 164 uses the correction values a and b determined by the correction value calculation circuit 162, the difference calculated by the first difference circuit 163a, and the difference calculated by the second difference circuit 163b.
  • a tracking signal TE (TE a ⁇ (te1-te0) ⁇ b ⁇ (te2-te0)) is generated.
  • the control circuit 165 outputs a control signal for controlling the motor 143 so as to track the metal antenna 128a based on the tracking signal TE.
  • x represents the amount of positional deviation from the track
  • ⁇ represents the phase difference of the detection signal te1 from the detection signal te0
  • ⁇ represents the detection of the detection signal te2.
  • the phase difference with respect to the signal te0 is represented, and ⁇ represents an offset.
  • the tracking signal TE is expressed as the following formula (4).
  • the coefficient of the first term on the right side of the above equation (4) may be 0. That is, the correction values a and b may satisfy the relationship of the following formula (5).
  • the coefficient of the first term on the right side of the above equation (4) is 0, so that the tracking signal TE is expressed by the above equation (4). It is represented only by the second term on the right side. At this time, the signal amplitude of the tracking signal TE is determined by the coefficient of the second term on the right side of the above equation (4).
  • the correction value calculation circuit 162 determines the correction value a based on the following equation (6), whereby the coefficient of the second term on the right side of the above equation (4) is “2” and the signal amplitude is “2”. "Is obtained.
  • FIG. 46A shows a signal (a ⁇ (te1 ⁇ te0)) obtained by weighting the difference between the detection signal te1 and the detection signal te0 with respect to the positional deviation from the track and the detection signal te2 and the detection signal te0. It is a graph which shows the intensity
  • the intensity of a ⁇ (te1-te0) and the intensity of b ⁇ (te2-te0) periodically change in the tracking period Tp with respect to the positional deviation from the track, and the position from the track by the correction values a and b. At positions where the deviation is 0, the values are equal to each other.
  • FIG. 46B is a graph showing a change in intensity of the tracking signal TE with respect to a positional deviation from the track.
  • the tracking signal TE is zero-crossed when the positional deviation from the track is zero, and is proportional to the positional deviation from the track. Tracking is performed by controlling the motor 143 based on the tracking signal TE. With this configuration, the recording or reproducing metal antenna 128a can be stably and accurately tracked with respect to the fine particles 102.
  • the semiconductor laser elements 107a, 107b, and 107c correspond to an example of a light source
  • the metal antennas 128a, 128b, and 128c correspond to an example of a plurality of resonance elements
  • the slider 141 is an example of a holding element.
  • the light receiving elements 120a, 120b, and 120c correspond to an example of the first detection element and the plurality of light receiving elements
  • the motor 103 corresponds to an example of the first moving element
  • the suspension 142 corresponds to the second moving element.
  • the tracking signal calculation circuit 161 corresponds to an example of a tracking signal calculation circuit
  • the yawing signal calculation circuit 151 corresponds to an example of a yawing signal calculation circuit
  • the piezo elements 144a and 144b correspond to an example of a rotation element. To do.
  • the slider 141 and the disk 101 are not in contact with each other, and the slider 141 is several nm on the disk 101.
  • the disk 101 can be scanned at a position of ⁇ tens of nm. Therefore, precise gap control can be performed without causing the disk 101 and the slider 141 to wear.
  • the metal antennas 128a, 128b, and 128c are arranged so as to be shifted in the longitudinal direction of the track. That is, the slider 141 is arranged by shifting the positions of the metal antennas 128a, 128b and 128c in the longitudinal direction of the track. Thereby, the interaction between the adjacent metal antennas 128a, 128b, and 128c can be suppressed, and the degree of freedom of the shape of the metal antennas 128a, 128b, and 128c is increased.
  • the positional deviation in the longitudinal direction of the tracks of the plurality of resonance elements is caused by the resonance of one resonance element of the plurality of resonance elements (metal antenna 128a, 128b or metal antenna 128c). It may be shifted beyond the thickness in the longitudinal direction of the track. Thereby, the interaction between a plurality of resonant elements can be further suppressed.
  • reflected light is detected instead of near-field light. This eliminates the need to fabricate minute light receiving elements 110a, 110b, and 110c in the immediate vicinity of the metal antennas 128a, 128b, and 128c, and facilitates fabrication of the optical information device.
  • the light receiving elements 120a, 120b, and 120c do not interact with the metal antennas 128a, 128b, and 128c. For this reason, the metal antennas 128a, 128b, and 128c and the disk 101 can be efficiently interacted, and tracking and information recording or reproduction can be performed efficiently.
  • a yawing signal calculation circuit 151 generates a yawing signal based on a change in the resonance state of the resonance element, and piezoelectric elements 144a and 144b use slider 141 (holding element) according to the yawing signal. Is rotated in a plane parallel to the surface of the disk 101. Therefore, the distance in the direction perpendicular to the track of the resonant elements (metal antennas 128b and 128c) with respect to the change in the track angle due to the eccentricity of the disk 101 or the movement in the direction perpendicular to the track using the motor 143 and the suspension 142. Is held constant. Therefore, stable tracking can be performed.
  • the tracking signal calculation circuit 161 calculates the correction values a and b from the detection signals te0, te1 and te2, and the product of the difference value (te1-te0) of the detection signal and the correction value a. And the difference between the product of the difference value (te2-te0) of the detection signal and the correction value b is output as the tracking signal TE. Therefore, a tracking signal can be obtained using the tracking metal antennas 128b and 128c arranged at an arbitrary distance from the recording or reproducing metal antenna 128a. Therefore, there are no restrictions on the distances between the metal antennas 128a, 128b, and 128c, and the fabrication of the optical information device is facilitated.
  • the pair of the semiconductor laser element and the light receiving element is disposed adjacent to one waveguide, but for example, a Y-shaped waveguide may be used.
  • a semiconductor laser element may be disposed on one side of the Y-shaped waveguide, and a light receiving element may be disposed on the other side.
  • a stepped step is formed on the end surface of the slider 141, and the metal antennas 128a, 128b, and 128c are arranged on each step.
  • the metal antennas 128a, 128b, and 128c only need to be shifted in the longitudinal direction of the track so as not to interact with each other.
  • the end surface of the slider 141 may be convex or concave.
  • the metal antennas 128a, 128b and 128c are arranged so as to be shifted in the longitudinal direction of the track.
  • the slider 141 and the air slider 132 are configured separately, but the present invention is not particularly limited to this, and the slider 141 may be enlarged.
  • the slider 141 may also have the function of an air slider that moves the slider 141 in a direction perpendicular to the surface of the disk 101. Also in this case, the gist of the present invention is not impaired.
  • the slider 141 is moved in the direction perpendicular to the track using the motor 143 and the suspension 142.
  • an actuator is used instead of the motor 143.
  • the suspension 142 may be moved in a direction perpendicular to the track.
  • fine particles made of a phase change material are used for recording or reproducing information, but the present invention is not particularly limited to this.
  • the optical information device is an optical information device that performs only reproduction, such as a ROM device, for example, uneven pits may be used instead of fine particles, or metal patterns may be used.
  • the shape of the metal antenna is a triangular plate shape.
  • the shape of the metal antenna is not particularly limited to the above example.
  • FIGS. A shape is also conceivable.
  • the shape of the metal antenna is not particularly limited as long as plasmon resonance occurs on the fine particles and the plasmon resonance state efficiently changes according to the distance from the track.
  • FIG. 17 when the shape of the metal antenna 117 is a square flat plate shape, the metal antenna 117 is vertically symmetric, so that the analysis is easier than the triangular flat plate shape.
  • the shape of the metal antenna 118 is a disc shape, the pattern can be easily produced as compared with the triangular plate shape.
  • FIG. 19 when the shape of the metal antenna 119 is a probe shape, near-field light can be generated more efficiently at the tip of the probe.
  • the difference between detection signals from a plurality of tracking metal antennas is 0 at the track position. What is necessary is just to be able to obtain a difference in detection signal according to the positional deviation from the track.
  • the number of metal antennas for tracking and the arrangement method are not particularly limited to the configuration shown in the fourth embodiment.
  • the plurality of waveguides 129a to 129c are arranged non-parallel to each other in order to suppress the waveguide mode coupling. However, if the waveguide mode coupling does not occur, the plurality of waveguides 129a to 129c may be arranged parallel to each other, and this does not impair the gist of the present invention.
  • the semiconductor laser elements 107a to 107c, the metal antennas 128a to 128c, and the light receiving elements 120a to 120c are arranged on the end face of the slider 141, but the present invention is not particularly limited to this. These elements may be arranged on the upper surface of the slider 141 or inside the slider 141, or these elements may be integrated on a single chip.
  • the optical information device includes three light sources (semiconductor laser elements 107a to 107c).
  • the optical information device includes one light source and guides light from one light source to the waveguide. The light may be incident on the metal antenna after being separated in three directions.
  • the optical information device includes one light source for recording or reproduction and one light source for tracking, and separates light from only the light source for tracking in two directions by a Y-shaped waveguide, thereby providing two metal antennas. Light may be incident on. These do not impair the gist of the present invention.
  • two piezo elements 144a and 144b are used as rotating elements for rotating the slider 141 in a plane parallel to the surface of the disk 101.
  • the slider 141 is a surface parallel to the surface of the disk 101.
  • Any driving element may be used as long as it is configured to rotate inside.
  • a configuration that mechanically drives using a motor a configuration that drives using electrostatic force or magnetic force, a configuration that uses thermal expansion, and the like can be considered.
  • the distance may be longer than the tracking period Tp.
  • FIG. 47 is a diagram for explaining another arrangement example of the metal antennas 128a, 128b, and 128c in the fourth embodiment of the present invention
  • FIG. 48 is a diagram illustrating the metal antenna in the fourth embodiment of the present invention. It is a figure shown for demonstrating another example of arrangement
  • the distance P1 in the direction perpendicular to the track between the tip position 171a of the metal antenna 128a and the tip position 171b of the metal antenna 128b is equal to or longer than the tracking period Tp, and the tip position 171a of the metal antenna 128a.
  • the distance P2 in the direction perpendicular to the track between the tip end position 171c of the metal antenna 128c and the tracking period Tp may be shorter.
  • the distance P1 may be shorter than the tracking period Tp, and the distance P2 may be longer than the tracking period Tp.
  • yawing is performed by subtracting the addition value (te1 0 + te2 0 ) of the initial value te1 0 and the initial value te2 0 from the addition value (te1 + te2) of the detection signal te1 and the detection signal te2.
  • the signal YE2 is generated, the generated yawing signal YE2 is multiplied by an appropriate integer according to the positional deviation from the track or the distances P1 and P2 in the direction perpendicular to the track of the metal antennas 128a, 128b and 128c.
  • the sensitivity of the signal YE2 may be adjusted so as to be always constant.
  • the detection signals te0, te1, and te2 are assumed as in the above equations (1) to (3), but the detection signals te0, te1, and te2 are in the above equation (1).
  • it is not represented by a simple expression as in (3) only the components represented by the above expressions (1) to (3) are extracted from the detection signals te0, te1 and te2 by signal processing and used. Only a component that changes in the tracking period Tp with respect to the positional deviation from the track may be extracted from the generated tracking signal TE and used.
  • FIG. 49 is a flowchart for explaining the tracking method according to the fourth embodiment of the present invention.
  • the semiconductor laser elements 107a, 107b, and 107c that are light sources emit light, and light is incident on the metal antennas 128a, 128b, and 128c that are a plurality of resonance elements to excite plasmon resonance.
  • the metal antennas 128 a, 128 b, and 128 c are designed so that the plasmon resonance condition is satisfied on the fine particle 102. Plasmon resonance weakens as the positional deviation from the track increases.
  • the light receiving elements 110a, 110b and 110c individually detect changes in the resonance state of the metal antennas 128a, 128b and 128c, and output detection signals te0, te1 and te2.
  • the metal antennas 128a, 128b, and 128c are designed such that the intensity of reflected light from the metal antennas 128a, 128b, and 128c decreases when plasmon resonance is excited.
  • the reflected light intensity from the metal antennas 128a, 128b, and 128c individually by the light receiving elements 120a, 120b, and 120c, it is possible to detect changes in the resonance state of the individual metal antennas 128a, 128b, and 128c. it can.
  • the reflected light intensity from the metal antennas 128a, 128b, and 128c changes as shown in FIG. 13A with respect to the distance from the track, becomes a minimum value at the track position, and is separated from the track position by half of the tracking period Tp. The maximum value at the position.
  • the motor 143 scans the slider 141 by a small amount in the direction perpendicular to the track.
  • the light receiving elements 120b and 120c output detection signals te1 and te2 according to the displacement in the direction perpendicular to the track.
  • the phase comparison circuit 152 calculates the phase difference with respect to the displacement amount in the direction perpendicular to the track of the detection signals te1 and te2 as the yawing signal YE1.
  • the first control circuit 153 controls the piezo elements 144a and 144b based on the yawing signal YE1 so that the phase difference between the detection signals te1 and te2 becomes ⁇ radians.
  • the piezoelectric elements 144 a and 144 b rotate the slider 141 in a plane parallel to the surface of the disk 101.
  • the detection signals te1 and te2 change with the tracking period Tp with respect to the displacement amount in the direction perpendicular to the track.
  • the first sample and hold circuit 154a and the second sample and hold circuit 154b stores a value of the detection signal te1 and te2 when yawing signal YE1 becomes ⁇ radians as an initial value te1 0 and te2 0.
  • the motor 143 scans the slider 141 in a direction perpendicular to the track.
  • the light receiving elements 120b and 120c output detection signals te1 and te2 according to the displacement in the direction perpendicular to the track.
  • the correction value calculation circuit 162 calculates correction values a and b such that the tracking signal TE crosses zero at a position where the positional deviation from the track becomes zero. At this time, the correction value calculation circuit 162 determines the correction values a and b so as to satisfy the relationship of the above formula (5). When the correction value a satisfies the above equation (6), a tracking signal TE having a signal amplitude “2” is obtained.
  • the initial values te1 0 and te2 0 are constant values regardless of the presence or absence of off-track as shown in FIG. 41 because the phase difference with respect to the positional deviation from the track is ⁇ radians. Therefore, the yawing signal calculation circuit 151 can always generate the yawing signal YE2 regardless of the arrangement of the off-track or metal antennas 128a, 128b, and 128c.
  • the first addition circuit 155a adds the initial value te1 0 and the initial value te2 0 .
  • the second addition circuit 155b adds the detection signal te1 and the detection signal te2.
  • the difference circuit 156 subtracts the addition value (te1 0 + te2 0 ) of the initial value te1 0 and the initial value te2 0 from the addition value (te1 + te2) of the detection signal te1 and the detection signal te2, thereby obtaining the yawing signal YE2 calculate.
  • the second control circuit 157 controls the piezo elements 144a and 144b based on the yawing signal YE2.
  • the piezoelectric elements 144 a and 144 b rotate the slider 141 in a plane parallel to the surface of the disk 101.
  • the distance between the metal antennas 128b and 128c in the direction perpendicular to the track is maintained at half the tracking period Tp.
  • the first difference circuit 163a subtracts the detection signal te0 from the detection signal te1 and outputs it to the weighted difference circuit 164.
  • the second difference circuit 163b subtracts the detection signal te0 from the detection signal te2, and outputs the result to the weighted difference circuit 164.
  • the weighted difference circuit 164 is calculated by the correction value calculation circuit 162 from a value obtained by multiplying the correction value a calculated by the correction value calculation circuit 162 by the subtraction value (te1-te0) calculated by the first difference circuit 163a.
  • the tracking signal TE is zero-crossed at the track position regardless of the distance between the metal antennas 128b and 128c in the direction perpendicular to the track, and the positional deviation from the track is the tracking period Tp. It becomes the maximum value or the minimum value when it is 1/4.
  • the tracking signal TE can be generated using the metal antennas 128b and 128c separated by an arbitrary distance in the direction perpendicular to the track.
  • the motor 143 moves the slider 141 in a direction perpendicular to the track in accordance with the tracking signal TE calculated by the tracking signal calculation circuit 161.
  • the motor 143 moves the slider 141 in a direction perpendicular to the track to adjust the track position.
  • the tracking signal TE calculated by the weighted difference circuit 164 is output to the control circuit 165.
  • the control circuit 165 drives the motor 143 according to the tracking signal TE to move the slider 141 in a direction perpendicular to the track.
  • the recording or reproducing metal antenna 128a can be constantly and accurately tracked with respect to the fine particles 102.
  • the tracking signal TE and the yawing signals YE1 and YE2 are generated based on the detection signals te0, te1 and te2 from the light receiving elements 120a, 120b and 120c, but the detection signals te0, te1 and te2 May be removed by a low-pass filter, and high-frequency components of the tracking signal TE and yawing signals YE1 and YE2 may be removed by a low-pass filter.
  • the scanning step of scanning the holding element in the direction perpendicular to the track, the change in the resonance state of each of the plurality of resonance elements is individually detected, and the plurality of resonance elements
  • a rotating step of rotating in a plane parallel to the surface For this reason, the distance in the direction perpendicular to the tracks of the plurality of resonance elements can be adjusted to half the tracking period Tp.
  • the tracking method includes a yawing signal calculation step for calculating a yawing signal from the sum of a plurality of detection signals, and a holding element is rotated in a plane parallel to the surface of the information recording medium according to the yawing signal.
  • a rotation step for this reason, it is possible to correct the track angle change caused by the eccentricity of the information recording medium or the movement of the holding element by the motor 143, and always keep the distance in the direction perpendicular to the track of the plurality of resonance elements at half the tracking period Tp. Can do.
  • the tracking method includes a correction value calculation step for calculating a correction value from a plurality of detection signals, and a tracking signal calculation for calculating a difference between the products of the plurality of detection signals and the correction value as a tracking signal. Steps. Thereby, a tracking signal can be stably generated using a plurality of resonant elements arranged at an arbitrary distance.
  • An optical information device is an optical information device for recording or reproducing information on an information recording medium having a track, and a light source, light from the light source is incident thereon, and the information recording medium is mutually connected.
  • a plurality of resonant elements that change the resonance state according to the distance from the track, and the positions of the plurality of resonant elements are shifted in a direction perpendicular to the track, and between the plurality of resonant elements A holding element that holds the distance fixed, a first detection element that individually detects a change in the resonance state of each of the plurality of resonance elements, and the resonance state that is detected by the first detection element
  • a tracking signal calculation circuit for calculating a tracking signal based on the change of the tracking signal, and the holding element in the track according to the tracking signal calculated by the tracking signal calculation circuit Comprising a first moving element that moves in a straight direction, the.
  • the holding element is arranged by shifting the position of the plurality of resonance elements in a direction perpendicular to the track, and holds the distance between the plurality of resonance elements fixed at a constant value.
  • the first detection element individually detects a change in the resonance state of each of the plurality of resonance elements.
  • the tracking signal calculation circuit calculates a tracking signal based on a change in the resonance state detected by the first detection element.
  • the first moving element moves the holding element in a direction perpendicular to the track in accordance with the tracking signal calculated by the tracking signal calculation circuit.
  • the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is fixed and held constant.
  • the relative position between the element and the track does not change. Therefore, stable and highly accurate tracking that depends only on the displacement from the track position can be performed.
  • the detection signal since a change in the resonance state of each of the plurality of resonance elements is individually detected and a tracking signal is calculated based on the detected change in the resonance state, the detection signal has an optical constant around the plurality of resonance elements.
  • a tracking signal having a high degree of modulation can be obtained with respect to a minute positional deviation from the track, which reacts sensitively to changes. Therefore, stable and highly accurate tracking can be performed.
  • the optical information apparatus may further include a second moving element that moves the plurality of resonant elements in a direction perpendicular to a surface of the information recording medium, and the second moving element includes the holding element and the holding element. It is preferable that the distance between the information recording medium and the holding element is kept constant by the force of the airflow flowing between the information recording medium.
  • the second moving element moves the plurality of resonant elements in a direction perpendicular to the surface of the information recording medium.
  • the second moving element keeps the distance between the information recording medium and the holding element constant by the force of the airflow flowing between the holding element and the information recording medium.
  • the distance between the information recording medium and the holding element is kept constant by the force of the airflow flowing between the holding element and the information recording medium, a plurality of resonance elements and the information recording medium can be recorded with a simple configuration.
  • the distance to the medium can be kept constant.
  • the optical information apparatus may further include a second moving element that moves the plurality of resonant elements in a direction perpendicular to a surface of the information recording medium, and the second moving element includes the holding element and the holding element. It is preferable to contact the information recording medium.
  • the second moving element moves the plurality of resonant elements in a direction perpendicular to the surface of the information recording medium.
  • the second moving element brings the holding element and the information recording medium into contact with each other. Therefore, the distance between the plurality of resonance elements and the information recording medium can be easily controlled.
  • the plurality of resonance elements may be detected in accordance with a second detection element that detects a distance between the plurality of resonance elements and the information recording medium, and a detection signal from the second detection element. It is preferable to further include a second moving element that moves the plurality of resonant elements in a direction perpendicular to the surface of the information recording medium so that the distance between the element and the information recording medium is constant.
  • the second detection element detects the distance between the plurality of resonance elements and the information recording medium.
  • the second moving element has a plurality of resonant elements placed on the surface of the information recording medium such that distances between the plurality of resonant elements and the information recording medium are constant according to a detection signal from the second detecting element. Move in a direction perpendicular to.
  • the distance between the plurality of resonance elements and the information recording medium is detected, the distance between the plurality of resonance elements and the information recording medium can be controlled with higher accuracy.
  • the first detection element includes a plurality of light receiving elements
  • the optical information device includes a plurality of waveguides that guide light from the plurality of resonance elements to the plurality of light receiving elements. It is preferable to further comprise.
  • the first detection element includes a plurality of light receiving elements.
  • the plurality of waveguides guide light from the plurality of resonance elements to the plurality of light receiving elements. Therefore, it is possible to reliably detect a change in the resonance state of each of the plurality of resonance elements.
  • the light source includes a plurality of light sources that emit light having different wavelengths, and the plurality of resonance elements determine a frequency of light emitted from each of the plurality of light sources as a resonance frequency.
  • the first detection element includes a plurality of light receiving elements, and the optical information device separates the plurality of lights having different frequencies from the plurality of resonance elements, and It is preferable to further include an optical element that guides each of the light beams to the corresponding light receiving elements.
  • the light source includes a plurality of light sources that emit light having different wavelengths.
  • the plurality of resonance elements are formed in a shape or material having a resonance frequency that is the frequency of light emitted from each of the plurality of light sources.
  • the first detection element includes a plurality of light receiving elements.
  • the optical element separates a plurality of lights having different frequencies from the plurality of resonance elements, and guides each of the plurality of lights to a corresponding plurality of light receiving elements.
  • the individual resonance states of the plurality of resonance elements are detected using the difference in wavelength, it is not necessary to integrate the light source, the first detection element, and the plurality of resonance elements in a minute region, and the optical information device Can be easily manufactured.
  • the first detection element includes a plurality of light receiving elements arranged in a range in which near-field light generated from the plurality of resonance elements can be detected.
  • the plurality of light receiving elements are arranged in a range in which the near field light generated from the plurality of resonance elements can be detected, so that the near field light generated from the plurality of resonance elements can be individually detected. And a highly accurate and highly efficient tracking signal can be obtained.
  • the track is preferably defined by fine particles arranged in a line. According to this configuration, stable and highly accurate tracking can be performed on the fine particles arranged in a row.
  • the track is preferably defined by a groove. According to this configuration, stable and highly accurate tracking can be performed on the groove.
  • the distance between the plurality of resonant elements in the direction perpendicular to the track is half of the track pitch.
  • the tracking signal is maximum or minimum at a position where the positional deviation from the track is a quarter of the track pitch, and becomes zero at a position where the positional deviation from the track is half the track pitch.
  • the positional deviation from the track can be easily detected.
  • the polarization direction of incident light incident on the plurality of resonance elements from the light source is a direction perpendicular to the surface of the information recording medium.
  • the plurality of resonance elements can be held perpendicular to the surface of the information recording medium, and the light source and the plurality of resonance elements can be arranged in a plane parallel to the surface of the information recording medium.
  • the size of the optical device in the direction perpendicular to the surface of the information recording medium can be reduced.
  • the polarization direction of incident light incident on the plurality of resonant elements from the light source is a direction parallel to the surface of the information recording medium. According to this configuration, it is not necessary to hold the plurality of resonance elements perpendicular to the surface of the information recording medium, and thus the holding element can be easily manufactured.
  • the holding element is arranged by shifting the positions of the plurality of resonance elements in the longitudinal direction of the track.
  • the position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the thickness in the longitudinal direction of the track of one resonance element of the plurality of resonance elements.
  • it is.
  • the position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the thickness in the longitudinal direction of the track of one resonance element among the plurality of resonance elements. The interaction between them can be further suppressed.
  • the polarization direction of incident light incident on the plurality of resonance elements from the light source is a direction parallel to the surface of the information recording medium and a direction parallel to the track.
  • the position in the longitudinal direction of the track between the plurality of resonance elements is shifted more than the length in the longitudinal direction of the track of one resonance element of the plurality of resonance elements.
  • the polarization direction of the incident light incident on the plurality of resonance elements from the light source is parallel to the surface of the information recording medium and parallel to the track.
  • the position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the length in the longitudinal direction of the track of one resonance element of the plurality of resonance elements. Therefore, the position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the length in the longitudinal direction of the track of one resonance element among the plurality of resonance elements. The action can be further suppressed.
  • a yawing signal representing an inclination of the holding element in a plane parallel to the surface of the information recording medium based on a change in the resonance state detected by the first detection element. It is preferable to further include a yawing signal calculation circuit for calculating, and a rotation element for rotating the holding element in a plane parallel to the surface of the information recording medium according to the yawing signal calculated by the yawing signal calculation circuit. .
  • the yawing signal calculation circuit calculates a yawing signal that represents the inclination of the holding element in a plane parallel to the surface of the information recording medium, based on the change in the resonance state detected by the first detection element. To do.
  • the rotating element rotates the holding element in a plane parallel to the surface of the information recording medium in accordance with the yawing signal calculated by the yawing signal calculation circuit.
  • the distance in the direction perpendicular to the tracks of the plurality of resonance elements is kept constant against the eccentricity of the information recording medium or the inclination of the track generated by moving the holding element in the direction perpendicular to the track. Therefore, stable tracking can be performed.
  • the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements
  • the yawing signal calculation circuit includes the plurality of detection signals.
  • the phase difference with respect to the displacement amount of the signal in the direction perpendicular to the track is calculated, and the rotating element rotates the holding element in a plane parallel to the surface of the information recording medium so that the phase difference becomes ⁇ radians. It is preferable to make it.
  • the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements.
  • the yawing signal calculation circuit calculates a phase difference with respect to a displacement amount in a direction perpendicular to the track of the plurality of detection signals.
  • the rotating element rotates the holding element in a plane parallel to the surface of the information recording medium so that the phase difference is ⁇ radians.
  • the phase difference with respect to the displacement amount in the direction perpendicular to the track of the plurality of detection signals is ⁇ radians
  • the distance in the direction perpendicular to the track of the plurality of detection signals is half the track pitch. Misalignment can be easily detected.
  • the first detection element outputs a plurality of detection signals representing changes in the resonance states of the plurality of resonance elements
  • the tracking signal calculation circuit includes the first detection element. It is preferable to calculate a difference between the plurality of detection signals output by the detection element as the tracking signal.
  • the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements.
  • the tracking signal calculation circuit calculates a difference between a plurality of detection signals output by the first detection element as a tracking signal.
  • the tracking signal can be generated with a simple configuration.
  • the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements
  • the tracking signal calculation circuit includes the plurality of detection signals. Based on the signal, a correction value for correcting the positional deviation of the plurality of resonance elements from the track is calculated, and a difference between the plurality of detection signals corrected based on the calculated correction value is used as the tracking signal. It is preferable to calculate.
  • the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements.
  • the tracking signal calculation circuit calculates a correction value for correcting the positional deviation from the track of the plurality of resonance elements based on the plurality of detection signals, and the difference between the plurality of detection signals corrected based on the calculated correction value. Is calculated as a tracking signal.
  • the distance between one of the plurality of resonance elements and the center of the track is different from the distance between the other resonance element of the plurality of resonance elements and the center of the track.
  • an accurate tracking signal can be generated.
  • a tracking method is a tracking method in an optical information apparatus that records or reproduces information on an information recording medium having a track, and interacts with the information recording medium, at a distance from the track.
  • a light incident step for causing light from a light source to enter a plurality of resonance elements whose resonance states change in response, a detection step for individually detecting a change in the resonance state of each of the plurality of resonance elements, and detection in the detection step
  • a tracking signal calculation step for calculating a tracking signal based on the change in the resonance state, and positions of the plurality of resonance elements perpendicular to the track according to the tracking signal calculated in the tracking signal calculation step. Displaced in the direction, and the distance between the plurality of resonance elements is fixed and held constant Comprising a moving step, the moving the retaining element in a direction perpendicular to the track that.
  • the light incident step light from the light source is incident on the plurality of resonance elements that interact with the recording medium and change the resonance state according to the distance from the track.
  • the detection step a change in the resonance state of each of the plurality of resonance elements is individually detected.
  • the tracking signal calculation step the tracking signal is calculated based on the change in the resonance state detected in the detection step.
  • the movement step according to the tracking signal calculated in the tracking signal calculation step, the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is fixed to be constant.
  • the holding element to be held is moved in a direction perpendicular to the track.
  • the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is fixed and held constant.
  • the relative position between the element and the track does not change. Therefore, stable and highly accurate tracking that depends only on the displacement from the track position can be performed.
  • the detection signal since a change in the resonance state of each of the plurality of resonance elements is individually detected and a tracking signal is calculated based on the detected change in the resonance state, the detection signal has an optical constant around the plurality of resonance elements.
  • a tracking signal having a high degree of modulation can be obtained with respect to a minute positional deviation from the track, which reacts sensitively to changes. Therefore, stable and highly accurate tracking can be performed.
  • the optical information device and the tracking method according to the present invention enable high-precision tracking control in an optical information device that records or reproduces information at a high density exceeding the diffraction limit. This is useful for realizing an optical information device.
  • Such a high-density and large-capacity optical information device can be applied to many uses such as an optical disc player, an optical disc recorder, a computer, and a data server.

Abstract

According to the present invention a plurality of metal antennas (108b, 108c) onto which light is irradiated from semiconductor laser elements (107b, 107c) mutually operate with a disc (101) such that a resonance state changes in accordance with the distance from a track. A slider (104) arranges the plurality of metal antennas (108b, 108c) by displacing the position of the metal antennas in a direction orthogonal to the track while constantly fixing and maintaining the distance between the plurality of metal antennas (108b, 108c). Light-receiving elements (110b, 110c) separately detect each change in the resonance state of the plurality of metal antennas (108b, 108c). An operation amplifier (111) operates a tracking signal on the basis of the detected change in the resonance state. An actuator (106) moves the slider (104) in the direction orthogonal to the track in accordance with the operated tracking signal.

Description

光情報装置及びトラッキング方法Optical information apparatus and tracking method
　本発明は、トラックを有する情報記録媒体に情報を記録または再生する光情報装置、及び光情報装置のトラッキング方法に関するものである。 The present invention relates to an optical information apparatus for recording or reproducing information on an information recording medium having a track, and a tracking method for the optical information apparatus.
　近年、光情報記録の分野で近接場光を応用して光の回折限界を超えた高密度光記録又は高密度光再生を行う技術が注目されている。近接場光を用いて記録の高密度化を達成する方法として、特許文献１に記載されている従来の技術について図面を用いて説明する。図５０は、従来技術における近接場光ヘッドの構成を示す上面図であり、図５１は、従来技術における近接場光ヘッドの構成を示す側面図である。 Recently, in the field of optical information recording, attention has been paid to a technique for performing high-density optical recording or high-density optical reproduction exceeding the diffraction limit of light by applying near-field light. As a method for achieving high recording density using near-field light, the conventional technique described in Patent Document 1 will be described with reference to the drawings. FIG. 50 is a top view showing the configuration of the near-field optical head in the prior art, and FIG. 51 is a side view showing the configuration of the near-field optical head in the prior art.
　図５０及び図５１において、近接場光ヘッドは、光源８０２、光源８０２の放射光ＬＢを透過するプリズム８０３、及び放射光ＬＢの入射により近接場光ＮＬを発生する散乱体８０４を備える。放熱材８０５は、光源８０２に固定され、光源８０２で発生した熱を放熱する。また、検出素子８０６は、光ディスク８０１からの再生光を検出する。光源８０２、プリズム８０３、散乱体８０４、放熱材８０５及び検出素子８０６は、スライダ８０７により保持されている。スライダ８０７は、光ディスク８０１と散乱体８０４との間の距離が一定になるように、サスペンション８０８により保持されている。 50 and 51, the near-field light head includes a light source 802, a prism 803 that transmits the emitted light LB of the light source 802, and a scatterer 804 that generates near-field light NL when the emitted light LB enters. The heat dissipation material 805 is fixed to the light source 802 and dissipates heat generated by the light source 802. The detection element 806 detects reproduction light from the optical disc 801. A light source 802, a prism 803, a scatterer 804, a heat dissipation material 805, and a detection element 806 are held by a slider 807. The slider 807 is held by a suspension 808 so that the distance between the optical disc 801 and the scatterer 804 is constant.
　散乱体８０４から発生する近接場光ＮＬによって、相変化材料である光ディスク８０１の結晶相をアモルファス相に変化させることにより、記録マークが形成され、情報が光ディスク８０１に記録される。一方、情報の再生は、近接場光ＮＬが光ディスク８０１により散乱される割合は、記録マークの有無により変化するので、光ディスク８０１から戻ってくる散乱光の強度変化を検出することにより、情報が光ディスク８０１から再生される。 The near-field light NL generated from the scatterer 804 changes the crystal phase of the optical disk 801, which is a phase change material, to an amorphous phase, thereby forming a recording mark and recording information on the optical disk 801. On the other hand, in the reproduction of information, since the rate at which the near-field light NL is scattered by the optical disk 801 changes depending on the presence or absence of a recording mark, the information is detected by detecting the intensity change of the scattered light returning from the optical disk 801. Playback starts from 801.
　特許文献１によると、光源８０２、プリズム８０３、散乱体８０４、放熱材８０５及び検出素子８０６は、スライダ８０７に保持されて、いわゆる近接場光プローブスライダを構成する。そのため、きわめて小型化を図った上で、光ディスク８０１に近接場光ＮＬを用いて高密度に情報を記録または再生する近接場光ヘッド装置を実現できる。 According to Patent Document 1, the light source 802, the prism 803, the scatterer 804, the heat radiation member 805, and the detection element 806 are held by the slider 807 to form a so-called near-field optical probe slider. Therefore, it is possible to realize a near-field optical head device that records or reproduces information on the optical disc 801 with high density by using the near-field light NL while achieving a very small size.
　上記のように近接場光を利用して回折限界を超えた高密度光記録又は高密度光再生を行う技術が徐々に具体化されつつある。しかしながら、こうした近接場光ヘッド装置の実用化には記録又は再生技術だけでなく、数十ｎｍサイズのトラックに対してトラッキングを行う高精度なトラッキング技術が必要になる。 As described above, techniques for performing high-density optical recording or high-density optical reproduction exceeding the diffraction limit using near-field light are gradually being embodied. However, the practical application of such a near-field optical head device requires not only a recording or reproducing technique but also a highly accurate tracking technique for tracking a track of several tens of nanometers.
　高精度なトラッキングを行う方法として、特許文献２に記載されている従来の技術について図面を用いて説明する。図５２は、従来技術における高密度プローブメモリー再生装置の構成を示す概略図であり、図５３は、従来技術におけるプローブの取り付け状態及び変形状態を示す要部斜視図である。 The conventional technique described in Patent Document 2 will be described with reference to the drawings as a method for performing high-precision tracking. FIG. 52 is a schematic diagram showing a configuration of a high-density probe memory reproducing device in the prior art, and FIG. 53 is a perspective view of a principal part showing a probe attachment state and a deformation state in the conventional technology.
　図５２において、情報記録媒体９０１は、トラック状に形成された記録部９０２を含む。情報記録媒体９０１は、回転素子９０３によって回転される。複数のプローブ９０４は、スライダ９０５及びサスペンション９０６によって、１つの記録部９０２に対して接触可能な範囲に保持されている。複数のプローブ９０４の位置は、記録部９０２と接触することによって図５３に示すように変化する。サスペンション９０６は、駆動素子９０７によって保持され、トラックに垂直な方向に駆動される。 52, an information recording medium 901 includes a recording unit 902 formed in a track shape. The information recording medium 901 is rotated by a rotating element 903. The plurality of probes 904 are held by a slider 905 and a suspension 906 in a range where they can come into contact with one recording unit 902. The positions of the plurality of probes 904 change as shown in FIG. 53 by contacting the recording unit 902. The suspension 906 is held by a driving element 907 and is driven in a direction perpendicular to the track.
　図示しない光源からの入射光９０８が複数のプローブ９０４に照射される。複数の検出素子９１０は、複数のプローブ９０４からの反射光９０９を検出する。これにより、複数のプローブ９０４の変位が検出される。演算回路９１１は、複数の検出素子９１０から得られた複数の検出情報に基づいて再生信号及びトラッキング信号を計算して出力する。トラッキング信号は、駆動素子９０７に入力される。駆動素子９０７は、トラッキング信号に応じてサスペンション９０６を駆動する。これにより、複数のプローブ９０４のトラッキングが行われる。 Incident light 908 from a light source (not shown) is applied to the plurality of probes 904. The plurality of detection elements 910 detect reflected light 909 from the plurality of probes 904. Thereby, the displacement of the plurality of probes 904 is detected. The arithmetic circuit 911 calculates and outputs a reproduction signal and a tracking signal based on a plurality of detection information obtained from the plurality of detection elements 910. The tracking signal is input to the drive element 907. The drive element 907 drives the suspension 906 according to the tracking signal. Thereby, tracking of the plurality of probes 904 is performed.
　しかしながら、従来の複数のプローブを用いたトラッキング方法では、プローブが記録部を検出するためには、記録部との相互作用によりプローブの位置が変位しなければならない。そのため、複数のプローブと記録部との相対的な位置が変化してしまい、検出信号は、複数のプローブと記録部との間のトラックに垂直な方向の距離のみを反映していないという問題を有していた。 However, in the conventional tracking method using a plurality of probes, in order for the probe to detect the recording portion, the position of the probe must be displaced by the interaction with the recording portion. Therefore, the relative positions of the plurality of probes and the recording unit are changed, and the detection signal does not reflect only the distance in the direction perpendicular to the track between the plurality of probes and the recording unit. Had.
国際公開第２００７／１１１３０４号International Publication No. 2007/111304 特開平９－１６１３３８号公報JP-A-9-161338
　本発明は、上記の問題を解決するためになされたもので、安定かつ高精度なトラッキングを行うことができる光情報装置及びトラッキング方法を提供することを目的とするものである。 The present invention has been made to solve the above-described problems, and an object thereof is to provide an optical information device and a tracking method capable of performing stable and highly accurate tracking.
　本発明の一局面に係る光情報装置は、トラックを有する情報記録媒体に情報を記録又は再生する光情報装置であって、光源と、前記光源からの光が入射し、前記情報記録媒体と相互作用し、前記トラックからの距離に応じて共鳴状態が変化する複数の共鳴素子と、前記複数の共鳴素子の位置を前記トラックに垂直な方向にずらして配置し、かつ前記複数の共鳴素子間の距離を一定に固定して保持する保持素子と、前記複数の共鳴素子の各々の共鳴状態の変化を個別に検出する第１の検出素子と、前記第１の検出素子によって検出された前記共鳴状態の変化に基づいてトラッキング信号を演算するトラッキング信号演算回路と、前記トラッキング信号演算回路によって演算された前記トラッキング信号に応じて前記保持素子を前記トラックに垂直な方向に移動させる第１の移動素子と、を備える。 An optical information device according to one aspect of the present invention is an optical information device for recording or reproducing information on an information recording medium having a track, and a light source, light from the light source is incident thereon, and the information recording medium is mutually connected. A plurality of resonant elements that change the resonance state according to the distance from the track, and the positions of the plurality of resonant elements are shifted in a direction perpendicular to the track, and between the plurality of resonant elements A holding element that holds the distance fixed, a first detection element that individually detects a change in the resonance state of each of the plurality of resonance elements, and the resonance state that is detected by the first detection element A tracking signal calculation circuit for calculating a tracking signal based on the change of the tracking signal, and the holding element in the track according to the tracking signal calculated by the tracking signal calculation circuit Comprising a first moving element that moves in a straight direction, the.
　この構成によれば、複数の共鳴素子は、光源からの光が入射し、情報記録媒体と相互作用し、トラックからの距離に応じて共鳴状態が変化する。保持素子は、複数の共鳴素子の位置をトラックに垂直な方向にずらして配置し、かつ複数の共鳴素子間の距離を一定に固定して保持する。第１の検出素子は、複数の共鳴素子の各々の共鳴状態の変化を個別に検出する。トラッキング信号演算回路は、第１の検出素子によって検出された共鳴状態の変化に基づいてトラッキング信号を演算する。第１の移動素子は、トラッキング信号演算回路によって演算されたトラッキング信号に応じて保持素子をトラックに垂直な方向に移動させる。 According to this configuration, light from the light source enters the plurality of resonance elements, interacts with the information recording medium, and the resonance state changes according to the distance from the track. The holding element is arranged by shifting the position of the plurality of resonance elements in a direction perpendicular to the track, and holds the distance between the plurality of resonance elements fixed at a constant value. The first detection element individually detects a change in the resonance state of each of the plurality of resonance elements. The tracking signal calculation circuit calculates a tracking signal based on a change in the resonance state detected by the first detection element. The first moving element moves the holding element in a direction perpendicular to the track in accordance with the tracking signal calculated by the tracking signal calculation circuit.
　本発明によれば、複数の共鳴素子の位置がトラックに垂直な方向にずらして配置され、かつ複数の共鳴素子間の距離が一定に固定されて保持されるので、情報記録媒体との相互作用により複数の共鳴素子とトラックとの相対的な位置が変化することがない。そのため、トラック位置からの変位にのみ依存した安定かつ高精度なトラッキングを行うことができる。 According to the present invention, the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is held constant, so that the interaction with the information recording medium is possible. Thus, the relative positions of the plurality of resonance elements and the tracks do not change. Therefore, stable and highly accurate tracking that depends only on the displacement from the track position can be performed.
　また、複数の共鳴素子の各々の共鳴状態の変化が個別に検出され、検出された共鳴状態の変化に基づいてトラッキング信号が演算されるので、検出信号が複数の共鳴素子の周辺の光学定数の変化に敏感に反応し、トラックからの微小な位置ずれに対して変調度の高いトラッキング信号が得られる。そのため、安定かつ高精度なトラッキングを行うことができる。 In addition, since a change in the resonance state of each of the plurality of resonance elements is individually detected and a tracking signal is calculated based on the detected change in the resonance state, the detection signal has an optical constant around the plurality of resonance elements. A tracking signal having a high degree of modulation can be obtained with respect to a minute positional deviation from the track, which reacts sensitively to changes. Therefore, stable and highly accurate tracking can be performed.
　本発明の目的、特徴及び利点は、以下の詳細な説明と添付図面とによって、より明白となる。 The objects, features and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.
本発明の実施の形態１における光情報装置の構成を示す概略図である。It is the schematic which shows the structure of the optical information apparatus in Embodiment 1 of this invention. 図１に示すスライダの構成を示す斜視図である。It is a perspective view which shows the structure of the slider shown in FIG. 図１に示すスライダの構成を示す側面図である。It is a side view which shows the structure of the slider shown in FIG. 図１に示すスライダの構成を示す上面図である。It is a top view which shows the structure of the slider shown in FIG. 本発明の実施の形態１における金属アンテナを示す拡大図である。It is an enlarged view which shows the metal antenna in Embodiment 1 of this invention. （Ａ）は、本発明の実施の形態１における金属アンテナのトラックからの距離に対する近接場光強度の変化を示すグラフであり、（Ｂ）は、複数の受光素子からの複数の検出信号の強度変化を示すグラフであり、（Ｃ）は、オペアンプにより出力されるトラッキング信号の強度変化を示すグラフである。(A) is a graph which shows the change of the near-field light intensity with respect to the distance from the track | truck of the metal antenna in Embodiment 1 of this invention, (B) is the intensity | strength of several detection signals from several light receiving elements. It is a graph which shows a change, (C) is a graph which shows the intensity | strength change of the tracking signal output by an operational amplifier. 本発明の実施の形態１の変形例におけるスライダの駆動方法について説明するための図である。It is a figure for demonstrating the drive method of the slider in the modification of Embodiment 1 of this invention. 本発明の実施の形態１におけるトラッキング方法について説明するためのフローチャートである。It is a flowchart for demonstrating the tracking method in Embodiment 1 of this invention. 本発明の実施の形態２における光情報装置の構成を示す概略図である。It is the schematic which shows the structure of the optical information apparatus in Embodiment 2 of this invention. 図９に示すスライダの構成を示す斜視図である。It is a perspective view which shows the structure of the slider shown in FIG. 図９に示すスライダの構成を示す側面図である。It is a side view which shows the structure of the slider shown in FIG. 図９に示すスライダの構成を示す上面図である。FIG. 10 is a top view showing the configuration of the slider shown in FIG. 9. （Ａ）は、本発明の実施の形態２における金属アンテナのトラックからの距離に対する金属アンテナからの反射光強度の変化を示すグラフであり、（Ｂ）は、トラッキング用の複数の受光素子からの複数の検出信号の強度変化を示すグラフであり、（Ｃ）は、オペアンプにより出力されるトラッキング信号の強度変化を示すグラフである。(A) is a graph which shows the change of the reflected light intensity from a metal antenna with respect to the distance from the track of the metal antenna in Embodiment 2 of this invention, (B) is from several light receiving elements for tracking. It is a graph which shows the intensity | strength change of a some detection signal, (C) is a graph which shows the intensity | strength change of the tracking signal output by an operational amplifier. 本発明の実施の形態２の第１の変形例におけるスライダを示す上面図である。It is a top view which shows the slider in the 1st modification of Embodiment 2 of this invention. 本発明の実施の形態２の第２の変形例におけるスライダを示す上面図である。It is a top view which shows the slider in the 2nd modification of Embodiment 2 of this invention. 本発明の実施の形態１及び２の変形例におけるスライダの構成を示す図である。It is a figure which shows the structure of the slider in the modification of Embodiment 1 and 2 of this invention. 本発明の実施の形態１及び２において、四角平板形状である金属アンテナを示す図である。In Embodiment 1 and 2 of this invention, it is a figure which shows the metal antenna which is a square plate shape. 本発明の実施の形態１及び２において、円板形状である金属アンテナを示す図である。In Embodiment 1 and 2 of this invention, it is a figure which shows the metal antenna which is a disk shape. 本発明の実施の形態１及び２において、プローブ形状である金属アンテナを示す図である。In Embodiment 1 and 2 of this invention, it is a figure which shows the metal antenna which is a probe shape. 本発明の実施の形態３における光情報装置の構成を示す概略図である。It is the schematic which shows the structure of the optical information apparatus in Embodiment 3 of this invention. 図２０に示す複数の金属アンテナの構成を示す斜視図である。It is a perspective view which shows the structure of the some metal antenna shown in FIG. 図２０に示す複数の金属アンテナの構成を示す上面図である。It is a top view which shows the structure of the some metal antenna shown in FIG. （Ａ）は、本発明の実施の形態３における金属アンテナのトラックからの距離に対する金属アンテナからの散乱光強度の変化を示すグラフであり、（Ｂ）は、トラッキング用の複数の受光素子からの複数の検出信号の強度変化を示すグラフであり、（Ｃ）は、オペアンプにより出力されるトラッキング信号の強度変化を示すグラフである。(A) is a graph which shows the change of the scattered light intensity from a metal antenna with respect to the distance from the track | truck of the metal antenna in Embodiment 3 of this invention, (B) is from several light receiving elements for tracking. It is a graph which shows the intensity | strength change of a some detection signal, (C) is a graph which shows the intensity | strength change of the tracking signal output by an operational amplifier. 本発明の実施の形態３において、扇板形状である金属アンテナを示す図である。In Embodiment 3 of this invention, it is a figure which shows the metal antenna which is a fan-plate shape. 本発明の実施の形態３において、ボウタイ形状である金属アンテナを示す図である。In Embodiment 3 of this invention, it is a figure which shows the metal antenna which is a bowtie shape. 本発明の実施の形態３において、ナノビーク形状である金属アンテナを示す図である。In Embodiment 3 of this invention, it is a figure which shows the metal antenna which is a nano beak shape. 本発明の実施の形態３においてトラッキング用の金属アンテナを近づけて配置する例を示す図である。It is a figure which shows the example which arrange | positions the metal antenna for tracking close in Embodiment 3 of this invention. 本発明の実施の形態３において、トラッキング用の金属アンテナの向きを異ならせて配置する例を示す図である。In Embodiment 3 of this invention, it is a figure which shows the example arrange | positioned by changing the direction of the metal antenna for tracking. 本発明の実施の形態３において、記録又は再生用の金属アンテナとトラッキング用の金属アンテナとの向きが互いに直交するように配置する例を示す図である。In Embodiment 3 of this invention, it is a figure which shows the example arrange | positioned so that the direction of the metal antenna for recording or reproduction | regeneration and the metal antenna for tracking may mutually orthogonally cross. 本発明の実施の形態４における光情報装置の構成を示す概略図である。It is the schematic which shows the structure of the optical information apparatus in Embodiment 4 of this invention. 本発明の実施の形態４における光情報装置の構成を示す上面図である。It is a top view which shows the structure of the optical information apparatus in Embodiment 4 of this invention. 図３０に示すスライダの構成を示す斜視図である。It is a perspective view which shows the structure of the slider shown in FIG. 図３０に示すスライダの構成を示す側面図である。It is a side view which shows the structure of the slider shown in FIG. 図３０に示すスライダの構成を示す上面図である。FIG. 31 is a top view showing the configuration of the slider shown in FIG. 30. 図３０に示すヨーイング信号演算回路の構成を示す図である。It is a figure which shows the structure of the yawing signal calculating circuit shown in FIG. Ｐ１＝Ｐ２＝Ｔｐ／４の場合におけるトラック角度変化について説明するための概念図である。It is a conceptual diagram for demonstrating the track angle change in the case of P1 = P2 = Tp / 4. Ｐ１＝Ｐ２＝Ｔｐ／４の場合におけるトラックからの位置ずれに対する複数の検出信号の強度変化を示す図である。It is a figure which shows the intensity | strength change of the some detection signal with respect to the position shift from a track | truck in the case of P1 = P2 = Tp / 4. Ｐ１＝Ｐ２＝Ｔｐ／４の場合におけるトラック中心と複数の金属アンテナの先端との距離に対する複数の検出信号の強度変化を示す図である。It is a figure which shows the intensity | strength change of several detection signals with respect to the distance of the track | truck center and the front-end | tip of several metal antenna in the case of P1 = P2 = Tp / 4. Ｐ１＝Ｐ２＝Ｔｐ／４の場合におけるトラック角度変化に対する複数の検出信号の複数の初期値からの変化量とヨーイング信号の変化とを示す図である。It is a figure which shows the variation | change_quantity from the some initial value of the some detection signal with respect to track angle change in the case of P1 = P2 = Tp / 4, and the change of a yawing signal. Ｐ１≠Ｐ２の場合におけるトラック角度変化について説明するための概念図である。It is a conceptual diagram for demonstrating the track angle change in the case of P1 <= P2. Ｐ１≠Ｐ２の場合におけるトラックからの位置ずれに対する複数の検出信号の強度変化を示す図である。It is a figure which shows the intensity | strength change of several detection signals with respect to the position shift from a track | truck in the case of P1 <= P2. Ｐ１≠Ｐ２の場合におけるトラック中心と複数の金属アンテナの先端との距離に対する複数の検出信号の強度変化を示す図である。It is a figure which shows the intensity | strength change of several detection signals with respect to the distance of the track center and the front-end | tip of several metal antenna in the case of P1 <= P2. Ｐ１≠Ｐ２の場合におけるトラック角度変化に対する複数の検出信号の複数の初期値の平均からの変化量とヨーイング信号の変化とを示す図である。It is a figure which shows the variation | change_quantity from the average of several initial value of several detection signal with respect to track angle change in the case of P1 <= P2, and the change of a yawing signal. Ｐ１≠Ｐ２の場合におけるトラック中心と複数の金属アンテナの先端の中点との距離に対するヨーイング信号の感度を示す図である。It is a figure which shows the sensitivity of the yawing signal with respect to the distance of the track center in the case of P1 <= P2 and the center point of the front-end | tip of several metal antenna. 図３０に示すトラッキング信号演算回路の構成を示す図である。It is a figure which shows the structure of the tracking signal calculating circuit shown in FIG. （Ａ）は、トラックからの位置ずれに対する検出信号ｔｅ１と検出信号ｔｅ０との差分に補正値ａを重み付けした信号（ａ×（ｔｅ１－ｔｅ０））及び検出信号ｔｅ２と検出信号ｔｅ０との差分に補正値ｂを重み付けした信号（ｂ×（ｔｅ２－ｔｅ０））の強度変化を示すグラフであり、（Ｂ）は、トラックからの位置ずれに対するトラッキング信号の強度変化を示すグラフである。(A) shows a signal (a × (te1−te0)) obtained by weighting the difference between the detection signal te1 and the detection signal te0 with respect to the positional deviation from the track and the difference between the detection signal te2 and the detection signal te0. 7 is a graph showing a change in intensity of a signal (b × (te2-te0)) weighted with a correction value b, and (B) is a graph showing a change in intensity of the tracking signal with respect to a positional deviation from the track. 本発明の実施の形態４において、金属アンテナの別の配置例について説明するための示す図である。In Embodiment 4 of this invention, it is a figure shown for demonstrating another example of arrangement | positioning of a metal antenna. 本発明の実施の形態４において、金属アンテナのさらに別の配置例について説明するための示す図である。In Embodiment 4 of this invention, it is a figure for demonstrating another example of arrangement | positioning of a metal antenna. 本発明の実施の形態４におけるトラッキング方法について説明するためのフローチャートである。It is a flowchart for demonstrating the tracking method in Embodiment 4 of this invention. 従来技術における近接場光ヘッドの構成を示す上面図である。It is a top view which shows the structure of the near-field optical head in a prior art. 従来技術における近接場光ヘッドの構成を示す側面図である。It is a side view which shows the structure of the near-field optical head in a prior art. 従来技術における高密度プローブメモリー再生装置の構成を示す概略図である。It is the schematic which shows the structure of the high-density probe memory reproducing | regenerating apparatus in a prior art. 従来技術におけるプローブの取り付け状態及び変形状態を示す要部斜視図である。It is a principal part perspective view which shows the attachment state and deformation | transformation state of the probe in a prior art.
　以下本発明の実施の形態について、図面を参照しながら説明する。なお、以下の実施の形態は、本発明を具体化した一例であって、本発明の技術的範囲を限定するものではない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention.
　（実施の形態１）
　図１は、本発明の実施の形態１における光情報装置の構成を示す概略図である。図２は、図１に示すスライダの構成を示す斜視図であり、図３は、図１に示すスライダの構成を示す側面図であり、図４は、図１に示すスライダの構成を示す上面図である。 (Embodiment 1)
FIG. 1 is a schematic diagram showing a configuration of an optical information device according to Embodiment 1 of the present invention. 2 is a perspective view showing the configuration of the slider shown in FIG. 1, FIG. 3 is a side view showing the configuration of the slider shown in FIG. 1, and FIG. 4 is a top view showing the configuration of the slider shown in FIG. FIG.
　図１～図４において、光情報装置は、半導体レーザ素子１０７ａ，１０７ｂ，１０７ｃ、金属アンテナ１０８ａ，１０８ｂ，１０８ｃ、導波路１０９ａ，１０９ｂ，１０９ｃ、受光素子１１０ａ，１１０ｂ，１１０ｃ、モータ１０３、スライダ１０４、サスペンション１０５、アクチュエータ１０６及びオペアンプ１１１を備える。 1 to 4, the optical information device includes semiconductor laser elements 107a, 107b, 107c, metal antennas 108a, 108b, 108c, waveguides 109a, 109b, 109c, light receiving elements 110a, 110b, 110c, a motor 103, and a slider 104. A suspension 105, an actuator 106, and an operational amplifier 111.
　図１において、情報記録媒体であるディスク１０１は、情報が記録または再生される相変化材料で構成された微粒子１０２が列状に配置されたトラック１１２を有している。ディスク１０１は、ディスク１０１を保持して回転させるモータ１０３により回転される。微粒子１０２を構成する相変化材料としては、例えば、Ｇｅ、Ｓｂ、Ｔｅ、Ｂｉ、Ｔｂ、Ｆｅ又はＣｏなどの合金からなる材料が考えられる。 In FIG. 1, a disc 101 as an information recording medium has a track 112 in which fine particles 102 made of a phase change material on which information is recorded or reproduced are arranged in a line. The disk 101 is rotated by a motor 103 that holds and rotates the disk 101. As the phase change material constituting the fine particles 102, for example, a material made of an alloy such as Ge, Sb, Te, Bi, Tb, Fe, or Co can be considered.
　ディスク１０１上には共鳴素子を保持する保持素子としてのスライダ１０４が配置されている。保持素子であるスライダ１０４は、複数の共鳴素子（金属アンテナ１０８ｂ及び１０８ｃ）の位置をトラック１１２に垂直な方向にずらして配置し、かつ複数の共鳴素子間の距離を一定に固定して保持する。スライダ１０４は、ばね素子としてのサスペンション１０５により常にディスク１０１と接するように押し付けられる。サスペンション１０５は、複数の共鳴素子をディスク１０１の表面に垂直な方向に移動させる第２の移動素子としても働く。 On the disk 101, a slider 104 is disposed as a holding element that holds the resonance element. The slider 104, which is a holding element, is arranged by shifting the positions of the plurality of resonance elements ( metal antennas 108b and 108c) in the direction perpendicular to the track 112, and holding the distance between the plurality of resonance elements fixed at a constant value. . The slider 104 is always pressed against the disk 101 by a suspension 105 as a spring element. The suspension 105 also functions as a second moving element that moves a plurality of resonance elements in a direction perpendicular to the surface of the disk 101.
　サスペンション１０５は、第１の移動素子としてのアクチュエータ１０６によってトラック１１２に垂直な方向に移動される。これにより、スライダ１０４は、トラック１１２に垂直な方向に移動される。すなわち、第１の移動素子であるアクチュエータ１０６は、トラッキング信号に応じて保持素子（スライダ１０４）をトラック１１２に垂直な方向に移動させる。ディスク１０１が回転されることにより、スライダ１０４は、ディスク１０１上を滑走しながら走査する。 The suspension 105 is moved in a direction perpendicular to the track 112 by an actuator 106 as a first moving element. As a result, the slider 104 is moved in a direction perpendicular to the track 112. That is, the actuator 106 as the first moving element moves the holding element (slider 104) in a direction perpendicular to the track 112 in accordance with the tracking signal. As the disk 101 is rotated, the slider 104 scans while sliding on the disk 101.
　以上のように、本実施の形態１の光情報装置においては、複数の共鳴素子を情報記録媒体の表面に垂直な方向に移動させる第２の移動素子は、サスペンション１０５（ばね素子）を含んでいる。このとき、サスペンション１０５は、スライダ１０４とディスク１０１とを接触させる。 As described above, in the optical information device according to the first embodiment, the second moving element that moves the plurality of resonant elements in the direction perpendicular to the surface of the information recording medium includes the suspension 105 (spring element). Yes. At this time, the suspension 105 brings the slider 104 and the disk 101 into contact with each other.
　図２、図３及び図４において、半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃは、光源を示す。本実施の形態では、光源としては、例えば半導体レーザ素子を用いる。半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃから出射される光の偏光方向はディスク１０１の表面に対して垂直な方向である。 2, 3, and 4, semiconductor laser elements 107 a, 107 b, and 107 c indicate light sources. In the present embodiment, for example, a semiconductor laser element is used as the light source. The polarization direction of the light emitted from the semiconductor laser elements 107 a, 107 b and 107 c is a direction perpendicular to the surface of the disk 101.
　また、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃは、半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃからの光によりプラズモン共鳴を励起する共鳴素子である。共鳴素子である金属アンテナ１０８ｂ及び１０８ｃは、ディスク１０１と相互作用しトラック１１２からの距離に応じて、共鳴状態が変化する。 The metal antennas 108a, 108b, and 108c are resonance elements that excite plasmon resonance by light from the semiconductor laser elements 107a, 107b, and 107c. The metal antennas 108b and 108c, which are resonance elements, interact with the disk 101, and the resonance state changes according to the distance from the track 112.
　スライダ１０４には、トラッキング用の金属アンテナ１０８ｂ及び１０８ｃが、記録又は再生用の金属アンテナ１０８ａを中心にして、トラック１１２に垂直な方向に並んで配置される。金属アンテナ１０８ｂ及び１０８ｃは、金属アンテナ１０８ａからトラック１１２に垂直な方向にそれぞれ距離Ｐだけ離れた位置に配置される。距離Ｐは、トラッキング周期（トラックピッチ）Ｔｐの４分の１である。このとき、金属アンテナ１０８ｂと金属アンテナ１０８ｃとの間のトラック１１２に垂直な方向の距離（２Ｐ）は、トラッキング周期Ｔｐの２分の１に固定される。 On the slider 104, tracking metal antennas 108b and 108c are arranged side by side in a direction perpendicular to the track 112 with the recording or reproduction metal antenna 108a as the center. The metal antennas 108b and 108c are disposed at positions separated from the metal antenna 108a by a distance P in the direction perpendicular to the track 112, respectively. The distance P is a quarter of the tracking period (track pitch) Tp. At this time, the distance (2P) in the direction perpendicular to the track 112 between the metal antenna 108b and the metal antenna 108c is fixed to one half of the tracking period Tp.
　３つの半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃから照射された光は、光を導く光学素子としての３つの導波路１０９ａ、１０９ｂ及び１０９ｃによりそれぞれ個別に３つの金属アンテナ１０８ａ、１０８ｂ及び１０８ｃに導かれ、プラズモン共鳴を励起する。３つの導波路１０９ａ、１０９ｂ及び１０９ｃは、導波モード結合を抑制するために互いに非平行に配置される。導波路１０９ａ、１０９ｂ及び１０９ｃは、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃから離れるにつれて、導波路１０９ａと導波路１０９ｂとの間の距離及び導波路１０９ａと導波路１０９ｃとの間の距離が広がるように配置されている。 The light emitted from the three semiconductor laser elements 107a, 107b and 107c is individually guided to the three metal antennas 108a, 108b and 108c by the three waveguides 109a, 109b and 109c as optical elements for guiding the light, Excites plasmon resonance. The three waveguides 109a, 109b and 109c are arranged non-parallel to each other in order to suppress waveguide mode coupling. The waveguides 109a, 109b, and 109c are arranged so that the distance between the waveguide 109a and the waveguide 109b and the distance between the waveguide 109a and the waveguide 109c increase as the distance from the metal antennas 108a, 108b, and 108c increases. Has been.
　金属アンテナ１０８ａ、１０８ｂ及び１０８ｃの頂点部分には、それぞれ検出素子としての受光素子１１０ａ、１１０ｂ及び１１０ｃが取り付けられている。受光素子１１０ａ、１１０ｂ及び１１０ｃは、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃから発生する近接場光の強度を個別に検出する。すなわち、第１の検出素子である受光素子１１０ｂ及び１１０ｃは、複数の共鳴素子（金属アンテナ１０８ｂ及び１０８ｃ）の各々の共鳴状態の変化を、個別に検出する。 Light receiving elements 110a, 110b, and 110c as detection elements are attached to the apex portions of the metal antennas 108a, 108b, and 108c, respectively. The light receiving elements 110a, 110b and 110c individually detect the intensity of near-field light generated from the metal antennas 108a, 108b and 108c. That is, the light receiving elements 110b and 110c, which are first detection elements, individually detect changes in the resonance states of the plurality of resonance elements ( metal antennas 108b and 108c).
　以上のように、本実施の形態１の光情報装置においては、複数の共鳴素子の各々の共鳴状態の変化を個別に検出して出力する第１の検出素子は、複数の共鳴素子（金属アンテナ１０８ｂ及び１０８ｃ）から発生する近接場光を検出可能な範囲に配置された複数の受光素子１１０ｂ及び１１０ｃを含む。 As described above, in the optical information device according to the first embodiment, the first detection element that individually detects and outputs the change in the resonance state of each of the plurality of resonance elements is the plurality of resonance elements (metal antennas). 108b and 108c) includes a plurality of light receiving elements 110b and 110c arranged in a range in which near-field light generated from 108b and 108c) can be detected.
　金属アンテナ１０８ａ、１０８ｂ及び１０８ｃの形状は、例えば図５に示すような金、銀、銅、チタン、アルミ又はクロムなどの三角平板形状である。図５において、金属アンテナ１０８ａは三角形の頂点が微粒子１０２の表面に最も近接するように配置されており、プラズモン共鳴が励起されることにより三角形の頂点近傍に強い近接場光が発生する。２つの金属粒子間の相互作用は、金属粒子間の距離が数十ｎｍ以下であるときに顕著に現れ、数ｎｍでさらに顕著になる（Ｃｏｎｆｉｎｅｄ　ｐｌａｓｍｏｎｓ　ｉｎ　ｎａｎｏｆａｂｒｉｃａｔｅｄ　ｓｉｎｇｌｅ　ｓｉｌｖｅｒ　ｐａｒｔｉｃｌｅ　ｐａｉｒｓ：　ｅｘｐｅｒｉｍｅｎｔａｌ　ｏｂｓｅｒｖａｔｉｏｎｓ　ｏｆ　ｓｔｒｏｎｇ　ｉｎｔｅｒｐａｒｔｉｃｌｅ　ｉｎｔｅｒａｃｔｉｏｎｓ，Ｌ．Ｇｕｎｎａｒｓｓｏｎ　ｅｔ．ａｌ．，Ｊ．Ｐｈｙｓ．Ｃｈｅｍ．Ｂ，２００５，１０９，１０７９－１０８７）。つまり、金属アンテナ１０８ａと微粒子１０２の表面との距離は、数十ｎｍ以下であることが好ましく、数ｎｍであることがより好ましい。なお、図５では特に図示していないが、金属アンテナ１０８ｂ及び１０８ｃについても金属アンテナ１０８ａと同様に配置され、三角形の頂点近傍に強い近接場光が発生する。 The shape of the metal antennas 108a, 108b and 108c is a triangular flat plate shape such as gold, silver, copper, titanium, aluminum or chrome as shown in FIG. In FIG. 5, the metal antenna 108a is arranged so that the vertex of the triangle is closest to the surface of the fine particle 102, and strong near-field light is generated in the vicinity of the vertex of the triangle when plasmon resonance is excited. The interaction between two metal particles appears prominently when the distance between the metal particles is several tens of nanometers or less, and becomes more prominent at a few nanometers (Confined plasmas in nanofabricated particulates: experimental observers. interactions, L. Gunnarsson et.al., J. Phys. Chem. B, 2005, 109, 1079-1087). That is, the distance between the metal antenna 108a and the surface of the fine particle 102 is preferably several tens of nm or less, and more preferably several nm. Although not specifically shown in FIG. 5, the metal antennas 108b and 108c are also arranged in the same manner as the metal antenna 108a, and strong near-field light is generated near the apex of the triangle.
　図６（Ａ）は、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃのトラック１１２からの距離に対する近接場光強度の変化を示すグラフである。図６（Ｂ）は、受光素子１１０ｂからの検出信号ｔｅ１及び受光素子１１０ｃからの検出信号ｔｅ２の強度変化を示すグラフである。図６（Ｃ）は、オペアンプ１１１により出力される検出信号ｔｅ１と検出信号ｔｅ２との差であるトラッキング信号ＴＥの強度変化を示すグラフである。 FIG. 6A is a graph showing a change in near-field light intensity with respect to the distance from the track 112 of the metal antennas 108a, 108b, and 108c. FIG. 6B is a graph showing changes in the intensity of the detection signal te1 from the light receiving element 110b and the detection signal te2 from the light receiving element 110c. FIG. 6C is a graph showing a change in intensity of the tracking signal TE, which is the difference between the detection signal te1 and the detection signal te2 output from the operational amplifier 111.
　一般に、プラズモン共鳴の共鳴条件は、共鳴素子の周囲の媒質の誘電率に大きく依存する。そのため、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃの形状を、半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃの光の周波数に対して微粒子１０２上にてプラズモン共鳴条件が満たされるように設計すれば、発生する近接場光強度は、図６（Ａ）のように、トラック位置（トラック１１２からの距離がトラッキング周期Ｔｐと一致する位置）で最大となり、トラック１１２からの距離がトラッキング周期Ｔｐの半分となる位置で最小となる。 In general, the resonance condition of plasmon resonance greatly depends on the dielectric constant of the medium around the resonance element. Therefore, if the shape of the metal antennas 108a, 108b and 108c is designed so that the plasmon resonance condition is satisfied on the fine particle 102 with respect to the frequency of light of the semiconductor laser elements 107a, 107b and 107c, the generated near-field light is generated. As shown in FIG. 6A, the intensity is maximum at the track position (position where the distance from the track 112 coincides with the tracking period Tp) and minimum at the position where the distance from the track 112 is half the tracking period Tp. Become.
　受光素子１１０ａの検出信号は、再生信号として出力される。受光素子１１０ｂ及び１１０ｃの検出信号ｔｅ１及びｔｅ２は、トラッキング信号演算回路として機能するオペアンプ１１１に入力される。すなわち、受光素子１１０ｂ及び１１０ｃは、複数の共鳴素子（金属アンテナ１０８ｂ及び１０８ｃ）の各々の共鳴状態の変化を表す検出信号ｔｅ１及びｔｅ２を出力する。オペアンプ１１１は、受光素子１１０ｂ及び１１０ｃによって出力された検出信号ｔｅ１と検出信号ｔｅ２とのレベル差をトラッキング信号ＴＥとして演算する。このように、トラッキング信号演算回路であるオペアンプ１１１は、受光素子１１０ｂ及び１１０ｃによって検出された複数の共鳴素子（金属アンテナ１０８ｂ及び１０８ｃ）の各々の共鳴状態の変化に基づいてトラッキング信号ＴＥを演算する。 The detection signal of the light receiving element 110a is output as a reproduction signal. The detection signals te1 and te2 of the light receiving elements 110b and 110c are input to the operational amplifier 111 that functions as a tracking signal calculation circuit. In other words, the light receiving elements 110b and 110c output detection signals te1 and te2 representing changes in the resonance states of the plurality of resonance elements ( metal antennas 108b and 108c). The operational amplifier 111 calculates a level difference between the detection signal te1 and the detection signal te2 output by the light receiving elements 110b and 110c as the tracking signal TE. As described above, the operational amplifier 111 serving as the tracking signal calculation circuit calculates the tracking signal TE based on the change in the resonance state of each of the plurality of resonance elements ( metal antennas 108b and 108c) detected by the light receiving elements 110b and 110c. .
　本実施の形態１では、トラッキング用の金属アンテナ１０８ｂ及び１０８ｃは、記録又は再生用の金属アンテナ１０８ａに対してそれぞれトラック１１２に垂直な方向に、トラッキング周期Ｔｐの４分の１だけ離して設置されている。そのため、検出信号ｔｅ１と検出信号ｔｅ２との差を最大とすることができ、高精度なトラッキング信号ＴＥを得ることができる。 In the first embodiment, the tracking metal antennas 108b and 108c are set apart from the recording or reproducing metal antenna 108a by a quarter of the tracking period Tp in the direction perpendicular to the track 112, respectively. ing. Therefore, the difference between the detection signal te1 and the detection signal te2 can be maximized, and a highly accurate tracking signal TE can be obtained.
　出力されたトラッキング信号ＴＥはアクチュエータ１０６に入力される。アクチュエータ１０６は、トラッキング信号ＴＥに対応してスライダ１０４をトラック１１２に垂直な方向に駆動する。かかる構成により、記録又は再生用の金属アンテナ１０８ａを微粒子１０２に対して、安定かつ高精度にトラッキングすることができる。 The output tracking signal TE is input to the actuator 106. The actuator 106 drives the slider 104 in a direction perpendicular to the track 112 in response to the tracking signal TE. With this configuration, the recording or reproducing metal antenna 108a can be stably and accurately tracked with respect to the fine particles 102.
　このように、本実施の形態１では、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃがディスク１０１の表面に対して垂直に配置されており、ディスク１０１の表面に対して垂直な偏光の光でプラズモン共鳴が励起される。このため、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃと相互作用するディスク１０１上の面積が狭くなり、高い分解能を得ることができる。 As described above, in the first embodiment, the metal antennas 108a, 108b, and 108c are arranged perpendicular to the surface of the disk 101, and the plasmon resonance is excited by the polarized light perpendicular to the surface of the disk 101. Is done. For this reason, the area on the disk 101 which interacts with the metal antennas 108a, 108b and 108c is reduced, and high resolution can be obtained.
　また、本実施の形態１では、複数の導波路１０９ａ、１０９ｂ及び１０９ｃを用いて半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃからの光が個別に金属アンテナ１０８ａ、１０８ｂ及び１０８ｃに入射する。そして、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃに取り付けられた受光素子１１０ａ、１１０ｂ及び１１０ｃでそれぞれの金属アンテナ１０８ａ、１０８ｂ及び１０８ｃの近接場光強度が個別に直接検出される。このため、高精度で高効率なトラッキング信号を得ることができる。 In the first embodiment, light from the semiconductor laser elements 107a, 107b, and 107c is individually incident on the metal antennas 108a, 108b, and 108c using the plurality of waveguides 109a, 109b, and 109c. The near-field light intensity of each of the metal antennas 108a, 108b, and 108c is directly detected individually by the light receiving elements 110a, 110b, and 110c attached to the metal antennas 108a, 108b, and 108c. For this reason, a highly accurate and highly efficient tracking signal can be obtained.
　また、本実施の形態１では、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃと微粒子１０２とのディスク１０１の表面に垂直な方向の距離を変化させることがない。このため、トラック１１２に垂直な方向の変位にのみ依存した安定かつ高精度なトラッキング信号を得ることができる。 In the first embodiment, the distance between the metal antennas 108a, 108b and 108c and the fine particles 102 in the direction perpendicular to the surface of the disk 101 is not changed. Therefore, a stable and highly accurate tracking signal that depends only on the displacement in the direction perpendicular to the track 112 can be obtained.
　また、本実施の形態１では、スライダ１０４がディスク１０１上を滑走する。このため、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃとディスク１０１の表面との距離を複雑な構成を用いずに常に一定値に保つことができる。このため、安定したトラッキングを行うことができる。 In the first embodiment, the slider 104 slides on the disk 101. For this reason, the distance between the metal antennas 108a, 108b and 108c and the surface of the disk 101 can always be kept constant without using a complicated configuration. For this reason, stable tracking can be performed.
　なお、本実施の形態１では、情報記録媒体としてディスクを用いているが、スライダ１０４がディスク全域を移動する構成であればよく、情報記録媒体の形状は円形に限定されない。 In Embodiment 1, a disk is used as the information recording medium. However, the slider 104 may be configured to move over the entire area of the disk, and the shape of the information recording medium is not limited to a circle.
　また、本実施の形態１では、ディスク１０１をモータ１０３で回転させて、スライダ１０４がディスク１０１上を走査する構成としているが、スライダが情報記録媒体全域を移動する構成であればよい。図７は、本発明の実施の形態１の変形例におけるスライダの駆動方法について説明するための図である。図７に示すように、本実施の形態１の変形例における光情報装置は、スライダ１０４をトラック１１２に垂直な方向に移動させる駆動素子１１４と、スライダ１０４をトラック１１２に平行な方向に移動させる駆動素子１１５とを備える。情報記録媒体１１３は、例えばカード状であり、所定の位置に固定される。スライダ１０４は、固定された情報記録媒体１１３上を駆動素子１１４，１１５によって駆動され、情報記録媒体１１３上全域を走査する。このような構成であっても、本発明の主旨が損なわれるものではない。 In the first embodiment, the disk 101 is rotated by the motor 103 and the slider 104 scans the disk 101. However, the slider may be configured to move over the entire information recording medium. FIG. 7 is a diagram for explaining a slider driving method in a modification of the first embodiment of the present invention. As shown in FIG. 7, the optical information device in the modification of the first embodiment moves the slider 104 in a direction perpendicular to the track 112 and the slider 104 moves in a direction parallel to the track 112. And a drive element 115. The information recording medium 113 has a card shape, for example, and is fixed at a predetermined position. The slider 104 is driven on the fixed information recording medium 113 by driving elements 114 and 115 to scan the entire area of the information recording medium 113. Even with such a configuration, the gist of the present invention is not impaired.
　なお、本実施の形態１において、ディスク１０１が情報記録媒体の一例に相当し、半導体レーザ素子１０７ｂ，１０７ｃが光源の一例に相当し、金属アンテナ１０８ｂ，１０８ｃが複数の共鳴素子の一例に相当し、スライダ１０４が保持素子の一例に相当し、受光素子１１０ｂ，１１０ｃが第１の検出素子及び複数の受光素子の一例に相当し、オペアンプ１１１がトラッキング信号演算回路の一例に相当し、アクチュエータ１０６が第１の移動素子の一例に相当し、サスペンション１０５が第２の移動素子の一例に相当し、導波路１０９ｂ，１０９ｃが複数の導波路の一例に相当する。 In the first embodiment, the disk 101 corresponds to an example of an information recording medium, the semiconductor laser elements 107b and 107c correspond to an example of a light source, and the metal antennas 108b and 108c correspond to an example of a plurality of resonance elements. The slider 104 corresponds to an example of a holding element, the light receiving elements 110b and 110c correspond to an example of a first detection element and a plurality of light receiving elements, the operational amplifier 111 corresponds to an example of a tracking signal arithmetic circuit, and the actuator 106 The suspension 105 corresponds to an example of a first moving element, the suspension 105 corresponds to an example of a second moving element, and the waveguides 109b and 109c correspond to an example of a plurality of waveguides.
　次に、本発明の実施の形態１におけるトラッキング方法について実施の形態１における光情報装置を用いて説明する。 Next, the tracking method in the first embodiment of the present invention will be described using the optical information device in the first embodiment.
　図８は、本発明の実施の形態１におけるトラッキング方法について説明するためのフローチャートである。 FIG. 8 is a flowchart for explaining the tracking method according to the first embodiment of the present invention.
　図８のフローチャートに沿って実施の形態１におけるトラッキング方法を説明する。 The tracking method in the first embodiment will be described along the flowchart of FIG.
　まず、第１のステップ３０１において、光源である半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃは、光を出射し、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃに光を入射させてプラズモン共鳴を励起する。金属アンテナ１０８ａ、１０８ｂ及び１０８ｃは、微粒子１０２上でプラズモン共鳴条件が満たされるように設計されている。プラズモン共鳴は、トラックからの位置ずれが大きくなるにつれて弱まる。 First, in the first step 301, the semiconductor laser elements 107a, 107b, and 107c, which are light sources, emit light, and enter the metal antennas 108a, 108b, and 108c to excite plasmon resonance. The metal antennas 108 a, 108 b and 108 c are designed so that the plasmon resonance condition is satisfied on the fine particle 102. Plasmon resonance weakens as the positional deviation from the track increases.
　次に、第２のステップ３０２において、受光素子１１０ａ、１１０ｂ及び１１０ｃは、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃの共鳴状態の変化を個別に検出し、再生信号、検出信号ｔｅ１及び検出信号ｔｅ２を出力する。プラズモン共鳴により発生する近接場光の強度はプラズモン共鳴が強いほど大きくなる。このため、受光素子１１０ａ、１１０ｂ及び１１０ｃは、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃの周辺に発生する近接場光の強度を個別に検出することで、個々の金属アンテナ１０８ａ、１０８ｂ及び１０８ｃの共鳴状態の変化を検出することができる。 Next, in the second step 302, the light receiving elements 110a, 110b, and 110c individually detect changes in the resonance state of the metal antennas 108a, 108b, and 108c, and output a reproduction signal, a detection signal te1, and a detection signal te2. . The intensity of near-field light generated by plasmon resonance increases as the plasmon resonance increases. For this reason, the light receiving elements 110a, 110b, and 110c individually detect the intensity of near-field light generated around the metal antennas 108a, 108b, and 108c, so that the resonance states of the individual metal antennas 108a, 108b, and 108c are detected. Changes can be detected.
　プラズモン共鳴により発生する近接場光の強度は、トラックからの距離に対して図６（Ａ）のような変化を示し、トラック位置で最大値となり、トラック位置からトラッキング周期Ｔｐの半分だけ離れた位置で最小値となる。実施の形態１では、トラッキング用の金属アンテナ１０８ｂ及び１０８ｃは、記録又は再生用の金属アンテナ１０８ａに対してそれぞれトラックに垂直な方向（トラッキング方向）に、トラッキング周期Ｔｐの４分の１だけ離して設置されている。そのため、受光素子１１０ｂ及び１１０ｃは、図６（Ｂ）に示すような検出信号ｔｅ１及びｔｅ２を得る。 The intensity of the near-field light generated by plasmon resonance shows a change as shown in FIG. 6A with respect to the distance from the track, becomes a maximum value at the track position, and is a position away from the track position by half of the tracking period Tp. Becomes the minimum value. In the first embodiment, the tracking metal antennas 108b and 108c are separated from the recording or reproduction metal antenna 108a by a quarter of the tracking period Tp in a direction perpendicular to the track (tracking direction). is set up. Therefore, the light receiving elements 110b and 110c obtain detection signals te1 and te2 as shown in FIG.
　次に、第３のステップ３０３において、演算回路であるオペアンプ１１１は、受光素子１１０ｂ及び１１０ｃによって検出された共鳴状態の変化に基づいてトラッキング信号ＴＥを演算する。オペアンプ１１１は、検出信号ｔｅ１と検出信号ｔｅ２との差をトラッキング信号ＴＥとして演算する。受光素子１１０ｂ及び１１０ｃからの検出信号ｔｅ１及びｔｅ２は、オペアンプ１１１に入力される。オペアンプ１１１は、検出信号ｔｅ１と検出信号ｔｅ２との差を増幅し、トラッキング信号ＴＥとして出力する。 Next, in the third step 303, the operational amplifier 111 as an arithmetic circuit calculates the tracking signal TE based on the change in the resonance state detected by the light receiving elements 110b and 110c. The operational amplifier 111 calculates the difference between the detection signal te1 and the detection signal te2 as the tracking signal TE. Detection signals te1 and te2 from the light receiving elements 110b and 110c are input to the operational amplifier 111. The operational amplifier 111 amplifies the difference between the detection signal te1 and the detection signal te2 and outputs it as a tracking signal TE.
　実施の形態１の構成では、トラッキング用の金属アンテナ１０８ｂ及び１０８ｃは、記録又は再生用の金属アンテナ１０８ａに対してそれぞれトラックに垂直な方向に、トラッキング周期Ｔｐの４分の１だけ離して設置されている。このため、トラッキング信号ＴＥは、トラックからの位置ずれがトラッキング周期Ｔｐの４分の１となる位置で最大又は最小の値となり、トラックからの位置ずれがトラッキング周期Ｔｐの２分の１となる位置で０となる。 In the configuration of the first embodiment, the tracking metal antennas 108b and 108c are installed apart from the recording or reproducing metal antenna 108a by a quarter of the tracking period Tp in the direction perpendicular to the track. ing. For this reason, the tracking signal TE has a maximum or minimum value at a position where the positional deviation from the track becomes a quarter of the tracking period Tp, and a position where the positional deviation from the track becomes a half of the tracking period Tp. 0.
　次に、第４のステップ３０４において、アクチュエータ１０６は、オペアンプ１１１によって演算されたトラッキング信号ＴＥに応じて、スライダ１０４をトラックに垂直な方向に移動させる。オペアンプ１１１によって演算されたトラッキング信号ＴＥは、アクチュエータ１０６へ出力される。アクチュエータ１０６は、トラッキング信号ＴＥに応じてサスペンション１０５を駆動してスライダ１０４をトラックに垂直な方向に移動させる。 Next, in the fourth step 304, the actuator 106 moves the slider 104 in a direction perpendicular to the track in accordance with the tracking signal TE calculated by the operational amplifier 111. The tracking signal TE calculated by the operational amplifier 111 is output to the actuator 106. The actuator 106 drives the suspension 105 according to the tracking signal TE to move the slider 104 in a direction perpendicular to the track.
　実施の形態１では、トラッキング信号ＴＥが正の値の場合、アクチュエータ１０６は、スライダ１０４が金属アンテナ１０８ｂの方へ移動するようにサスペンション１０５を駆動する。また、トラッキング信号ＴＥが負の値の場合、アクチュエータ１０６は、スライダ１０４が金属アンテナ１０８ｃの方へ移動するようにサスペンション１０５を駆動する。 In Embodiment 1, when the tracking signal TE is a positive value, the actuator 106 drives the suspension 105 so that the slider 104 moves toward the metal antenna 108b. If the tracking signal TE is a negative value, the actuator 106 drives the suspension 105 so that the slider 104 moves toward the metal antenna 108c.
　上記第２のステップ３０２乃至第４のステップ３０４の処理が繰り返されることにより、記録又は再生用の金属アンテナ１０８ａを微粒子１０２に対して常に安定かつ高精度にトラッキングさせることができる。 By repeating the processing from the second step 302 to the fourth step 304, the recording or reproducing metal antenna 108a can be constantly and accurately tracked with respect to the fine particles 102.
　なお、本実施の形態１では、オペアンプ１１１は、受光素子１１０ｂ及び１１０ｃからの検出信号ｔｅ１及びｔｅ２の差を増幅してトラッキング信号ＴＥを作成しているが、光情報装置は、オペアンプ１１１とアクチュエータ１０６との間にローパスフィルタを設け、ローパスフィルタは、オペアンプ１１１からの出力の高周波成分を除去して、検出信号ｔｅ１及びｔｅ２の差の平均値をトラッキング信号ＴＥとして出力してもよい。 In the first embodiment, the operational amplifier 111 amplifies the difference between the detection signals te1 and te2 from the light receiving elements 110b and 110c to create the tracking signal TE. However, the optical information device includes the operational amplifier 111 and the actuator. A low-pass filter may be provided between the low-pass filter 106 and the low-pass filter may remove the high-frequency component output from the operational amplifier 111 and output an average value of the difference between the detection signals te1 and te2 as the tracking signal TE.
　以上のように、本実施の形態１のトラッキング方法は、トラックを有する情報記録媒体に情報を記録又は再生する光情報装置におけるトラッキング方法であって、情報記録媒体と相互作用し、トラックからの距離に応じて共鳴状態が変化する複数の共鳴素子に光源からの光を入射させる光入射ステップと、複数の共鳴素子の各々の共鳴状態の変化を個別に検出する検出ステップと、検出ステップにおいて検出された共鳴状態の変化に基づいてトラッキング信号を演算するトラッキング信号演算ステップと、トラッキング信号演算ステップにおいて演算されたトラッキング信号に応じて、複数の共鳴素子の位置をトラックに垂直な方向にずらして配置し、かつ複数の共鳴素子間の距離を一定に固定して保持する保持素子をトラックに垂直な方向に移動させる移動ステップと、を包含する。 As described above, the tracking method according to the first embodiment is a tracking method in an optical information device that records or reproduces information on an information recording medium having a track, and interacts with the information recording medium, and is a distance from the track. Detected in a detection step for detecting a change in the resonance state of each of the plurality of resonance elements, and a detection step for detecting the change in the resonance state of each of the plurality of resonance elements. The tracking signal calculation step for calculating the tracking signal based on the change in the resonance state, and the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track according to the tracking signal calculated in the tracking signal calculation step. The holding element that holds the fixed distance between the plurality of resonant elements is fixed to the one perpendicular to the track. Comprising a moving step of moving, to.
　このように、トラックからの距離に応じて共鳴状態の変化する複数の共鳴素子の位置がトラックに垂直な方向にずらして配置され、かつ複数の共鳴素子間の距離が一定に固定されて保持される。これにより、相互作用により複数の共鳴素子とトラック上の情報記録位置との相対的な位置が変化することがない。このため、トラック位置からの変位にのみ依存した安定かつ高精度なトラッキング信号を得ることができる。さらに、共鳴状態は共鳴素子周辺の光学定数の変化に敏感に反応する。このため、トラック上の情報記録状態が表面形状変化を伴わない情報記録状態であっても安定かつ高精度にトラッキングすることができる。 As described above, the positions of the plurality of resonance elements whose resonance states change according to the distance from the track are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is fixed and held constant. The As a result, the relative position between the plurality of resonance elements and the information recording position on the track does not change due to the interaction. For this reason, a stable and highly accurate tracking signal depending only on the displacement from the track position can be obtained. Furthermore, the resonance state is sensitive to changes in the optical constants around the resonance element. For this reason, even if the information recording state on the track is an information recording state not accompanied by a change in surface shape, tracking can be performed stably and with high accuracy.
　また、本実施の形態１のトラッキング方法では、複数の共鳴素子の共鳴状態の変化が複数の受光素子によって個別に検出され、検出信号の差がトラッキング信号として出力される。これにより、検出信号が共鳴素子周辺の光学定数の変化に敏感に反応し、微小なトラックからの位置ずれに対して変調度の高いトラッキング信号が得られる。このため、安定かつ高精度なトラッキング信号を得ることができる。 Further, in the tracking method of the first embodiment, the change in the resonance state of the plurality of resonance elements is individually detected by the plurality of light receiving elements, and the difference between the detection signals is output as a tracking signal. As a result, the detection signal reacts sensitively to changes in the optical constants around the resonant element, and a tracking signal having a high degree of modulation with respect to a positional deviation from a minute track can be obtained. For this reason, a stable and highly accurate tracking signal can be obtained.
　（実施の形態２）
　次に、本発明の実施の形態２における光情報装置について説明する。 (Embodiment 2)
Next, an optical information device according to Embodiment 2 of the present invention will be described.
　図９は、本発明の実施の形態２における光情報装置の構成を示す概略図である。図１０は、図９に示すスライダの構成を示す斜視図であり、図１１は、図９に示すスライダの構成を示す側面図であり、図１２は、図９に示すスライダの構成を示す上面図である。図９～図１２において、図１～図４と同じ構成要素については同じ符号を用い、説明を省略する。 FIG. 9 is a schematic diagram showing the configuration of the optical information device according to the second embodiment of the present invention. 10 is a perspective view showing the configuration of the slider shown in FIG. 9, FIG. 11 is a side view showing the configuration of the slider shown in FIG. 9, and FIG. 12 is a top view showing the configuration of the slider shown in FIG. FIG. 9 to 12, the same components as those in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof is omitted.
　図９～図１２において、光情報装置は、半導体レーザ素子１０７ａ，１０７ｂ，１０７ｃ、金属アンテナ１２８ａ，１２８ｂ，１２８ｃ、導波路１２９ａ，１２９ｂ，１２９ｃ、受光素子１２０ａ，１２０ｂ，１２０ｃ、モータ１０３、スライダ１２４、サスペンション１２５、アクチュエータ１０６、オペアンプ１１１及びエアスライダ１３２を備える。 9 to 12, the optical information device includes semiconductor laser elements 107a, 107b, and 107c, metal antennas 128a, 128b, and 128c, waveguides 129a, 129b, and 129c, light receiving elements 120a, 120b, and 120c, a motor 103, and a slider 124. A suspension 125, an actuator 106, an operational amplifier 111, and an air slider 132.
　図９において、トラック状に並んだ微粒子１０２を有するディスク１０１がモータ１０３に固定されて保持されている。 In FIG. 9, a disk 101 having fine particles 102 arranged in a track shape is fixed to and held by a motor 103.
　また、保持素子としてのスライダ１２４は、共鳴素子としての金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの位置をトラック１１２に垂直な方向にずらして配置し、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃ間の距離を一定に固定して保持する。 The slider 124 as a holding element is arranged by shifting the positions of the metal antennas 128a, 128b and 128c as resonance elements in the direction perpendicular to the track 112, and the distance between the metal antennas 128a, 128b and 128c is fixed. And hold.
　共鳴素子である金属アンテナ１２８ｂ及び１２８ｃは、半導体レーザ素子１０７ｂ及び１０７ｃからの光が入射し、ディスク１０１と相互作用し、トラック１１２からの距離に応じて、共鳴状態が変化する。 Metal antennas 128b and 128c, which are resonant elements, receive light from semiconductor laser elements 107b and 107c, interact with disk 101, and the resonance state changes according to the distance from track 112.
　エアスライダ１３２は、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃをディスク１０１の表面に垂直な方向に移動させる。サスペンション１２５は、ばね素子で構成される。スライダ１２４とエアスライダ１３２とは、サスペンション１２５によってディスク１０１に対向して保持されている。ハードディスクドライブに採用されるフライングヘッドと同様の技術を用いてスライダ１２４とディスク１０１との距離が一定になるように保たれている。 The air slider 132 moves the metal antennas 128a, 128b, and 128c in a direction perpendicular to the surface of the disk 101. The suspension 125 is composed of a spring element. The slider 124 and the air slider 132 are held facing the disk 101 by the suspension 125. The distance between the slider 124 and the disk 101 is kept constant by using a technique similar to that of a flying head employed in a hard disk drive.
　以上のように、本実施の形態２の光情報装置においては、複数の共鳴素子を情報記録媒体の表面に垂直な方向に移動させる第２の移動素子は、サスペンション１２５（ばね素子）を含んでいる。このとき、サスペンション１２５は、スライダ１０４及びエアスライダ１３２とディスク１０１との間を流れる気流の力により、ディスク１０１とスライダ１０４及びエアスライダ１３２との間の距離を一定に保持する。 As described above, in the optical information device according to the second embodiment, the second moving element that moves the plurality of resonant elements in the direction perpendicular to the surface of the information recording medium includes the suspension 125 (spring element). Yes. At this time, the suspension 125 keeps the distance between the disk 101, the slider 104, and the air slider 132 constant by the force of the airflow flowing between the slider 104 and the air slider 132 and the disk 101.
　サスペンション１２５は、アクチュエータ１０６によってトラック１１２に垂直な方向に駆動される。これにより、第１の移動素子であるアクチュエータ１０６は、トラッキング信号に応じて保持素子（スライダ１２４）をトラック１１２に垂直な方向に移動させる。ディスク１０１が回転されることにより、スライダ１２４は、ディスク１０１上を走査する。 The suspension 125 is driven in a direction perpendicular to the track 112 by the actuator 106. As a result, the actuator 106 serving as the first moving element moves the holding element (slider 124) in a direction perpendicular to the track 112 in accordance with the tracking signal. As the disk 101 is rotated, the slider 124 scans the disk 101.
　金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、実施の形態１における金属アンテナ１０８ａ、１０８ｂ及び１０８ｃと同様に、例えば金、銀、銅、チタン、アルミ又はクロムなどの三角平板で構成される。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、三角形の頂点が微粒子１０２の表面に最も近接するように配置され、プラズモン共鳴が励起されることにより三角形の頂点近傍に強い近接場光が発生する。また、金属アンテナ１０８ａ、１０８ｂ及び１０８ｃと同様に、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃと微粒子１０２の表面との距離は、数十ｎｍ以下であることが好ましく、数ｎｍであることがより好ましい。 Similarly to the metal antennas 108a, 108b, and 108c in the first embodiment, the metal antennas 128a, 128b, and 128c are formed of triangular plates such as gold, silver, copper, titanium, aluminum, or chrome. The metal antennas 128a, 128b, and 128c are arranged so that the apex of the triangle is closest to the surface of the fine particle 102, and strong near-field light is generated near the apex of the triangle when plasmon resonance is excited. Similarly to the metal antennas 108a, 108b and 108c, the distance between the metal antennas 128a, 128b and 128c and the surface of the fine particles 102 is preferably several tens of nm or less, and more preferably several nm.
　図１０～図１２において、スライダ１２４は、トラック１１２の長手方向の端面にトラック１１２に垂直な方向に階段状の段差を有する。本実施の形態２では、階段状の端面は、トラック１１２の長手方向に位置の異なる３つの面を有する。 10 to 12, the slider 124 has a stepped step in the direction perpendicular to the track 112 on the end surface of the track 112 in the longitudinal direction. In the second embodiment, the stepped end face has three faces that are different in position in the longitudinal direction of the track 112.
　導波路１２９ａ、１２９ｂ及び１２９ｃは、半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃからの光を金属アンテナ１２８ａ、１２８ｂ及び１２８ｃに個別に導く。また、導波路１２９ａ、１２９ｂ及び１２９ｃは、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光を受光素子１２０ａ、１２０ｂ及び１２０ｃに個別に導く。受光素子１２０ａ、１２０ｂ及び１２０ｃは、半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃの近傍にそれぞれ配置されている。 The waveguides 129a, 129b and 129c individually guide light from the semiconductor laser elements 107a, 107b and 107c to the metal antennas 128a, 128b and 128c. The waveguides 129a, 129b and 129c individually guide the reflected light from the metal antennas 128a, 128b and 128c to the light receiving elements 120a, 120b and 120c. The light receiving elements 120a, 120b and 120c are arranged in the vicinity of the semiconductor laser elements 107a, 107b and 107c, respectively.
　また、受光素子１２０ａ、１２０ｂ及び１２０ｃは、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの各々の共鳴状態の変化を個別に検出する。受光素子１２０ａ、１２０ｂ及び１２０ｃは、複数の導波路１２９ａ、１２９ｂ及び１２９ｃにそれぞれ１つずつ取り付けられており、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光をそれぞれ個別に検出する。 The light receiving elements 120a, 120b, and 120c individually detect changes in the resonance states of the metal antennas 128a, 128b, and 128c. Each of the light receiving elements 120a, 120b, and 120c is attached to each of the plurality of waveguides 129a, 129b, and 129c, and individually detects the reflected light from the metal antennas 128a, 128b, and 128c.
　以上のように、本実施の形態２の光情報装置においては、複数の共鳴素子の各々の共鳴状態の変化を個別に検出して出力する第１の検出素子は、複数の受光素子１２０ｂ及び１２０ｃを含み、光情報装置は、複数の共鳴素子（金属アンテナ１２８ｂ及び１２８ｃ）からの光を複数の受光素子１２０ｂ及び１２０ｃに導く複数の導波路１２９ｂ及び１２９ｃを備える。 As described above, in the optical information device according to the second embodiment, the first detection elements that individually detect and output changes in the resonance states of the plurality of resonance elements are the plurality of light receiving elements 120b and 120c. The optical information device includes a plurality of waveguides 129b and 129c that guide light from the plurality of resonance elements ( metal antennas 128b and 128c) to the plurality of light receiving elements 120b and 120c.
　スライダ１２４の階段状の端面には、それぞれ１つずつ合計３つの金属アンテナ１２８ａ、１２８ｂ及び１２８ｃが固定されている。複数の導波路１２９ａ、１２９ｂ及び１２９ｃにより導かれた半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃからの光によりプラズモン共鳴が励起される。 A total of three metal antennas 128a, 128b, and 128c are fixed to the stepped end face of the slider 124, one each. Plasmon resonance is excited by light from the semiconductor laser elements 107a, 107b, and 107c guided by the plurality of waveguides 129a, 129b, and 129c.
　なお、２つの金属粒子間の相互作用は、金属粒子間の距離が数十ｎｍ以下であるときに顕著に現れる（Ｃｏｎｆｉｎｅｄ　ｐｌａｓｍｏｎｓ　ｉｎ　ｎａｎｏｆａｂｒｉｃａｔｅｄ　ｓｉｎｇｌｅ　ｓｉｌｖｅｒ　ｐａｒｔｉｃｌｅ　ｐａｉｒｓ：　ｅｘｐｅｒｉｍｅｎｔａｌ　ｏｂｓｅｒｖａｔｉｏｎｓ　ｏｆ　ｓｔｒｏｎｇ　ｉｎｔｅｒｐａｒｔｉｃｌｅ　ｉｎｔｅｒａｃｔｉｏｎｓ，Ｌ．Ｇｕｎｎａｒｓｓｏｎ　ｅｔ．ａｌ．，Ｊ．Ｐｈｙｓ．Ｃｈｅｍ．Ｂ，２００５，１０９，１０７９－１０８７）。そのため、金属アンテナ１２８ａと金属アンテナ１２８ｂとの間のトラックの長手方向の段差及び金属アンテナ１２８ａと金属アンテナ１２８ｃとの間のトラックの長手方向の段差の大きさＬは、数十ｎｍ以上とする。これにより、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃ間での相互作用を抑制することができ、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの形状の自由度が高くなる。 In addition, the interaction between two metal particles appears prominently when the distance between the metal particles is several tens of nanometers or less (Confined plasmas in nanofabricated partialspars: experiential severinstrands. Al., J. Phys. Chem. B, 2005, 109, 1079-1087). Therefore, the length L in the longitudinal direction of the track between the metal antenna 128a and the metal antenna 128b and the length L in the longitudinal direction of the track between the metal antenna 128a and the metal antenna 128c are set to several tens of nm or more. Thereby, the interaction between the metal antennas 128a, 128b and 128c can be suppressed, and the degree of freedom of the shape of the metal antennas 128a, 128b and 128c is increased.
　一方、トラッキング用の金属アンテナ１２８ｂ及び１２８ｃは、記録又は再生用の金属アンテナ１２８ａを中心にして、トラック１１２に垂直な方向に配置される。金属アンテナ１２８ｂ及び１２８ｃは、金属アンテナ１２８ａからトラック１１２に垂直な方向にそれぞれ距離Ｐだけ離れた位置に配置される。距離Ｐは、トラッキング周期（トラックピッチ）Ｔｐの４分の１である。このとき、金属アンテナ１２８ｂと金属アンテナ１２８ｃとの間のトラック１１２に垂直な方向の距離（２Ｐ）は、トラッキング周期Ｔｐの２分の１に固定される。 On the other hand, the tracking metal antennas 128b and 128c are arranged in a direction perpendicular to the track 112 with the recording or reproduction metal antenna 128a as the center. The metal antennas 128b and 128c are disposed at positions separated from the metal antenna 128a by a distance P in a direction perpendicular to the track 112, respectively. The distance P is a quarter of the tracking period (track pitch) Tp. At this time, the distance (2P) in the direction perpendicular to the track 112 between the metal antenna 128b and the metal antenna 128c is fixed to one half of the tracking period Tp.
　図１３（Ａ）は、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃのトラックからの距離に対する金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度の変化を示すグラフである。図１３（Ｂ）は、トラッキング用の受光素子１２０ｂ及び１２０ｃからの検出信号ｔｅ１及びｔｅ２の強度変化を示すグラフである。図１３（Ｃ）は、オペアンプ１１１により出力される検出信号ｔｅ１と検出信号ｔｅ２との差であるトラッキング信号ＴＥの強度変化を示すグラフである。 FIG. 13A is a graph showing changes in the intensity of reflected light from the metal antennas 128a, 128b, and 128c with respect to the distance from the track of the metal antennas 128a, 128b, and 128c. FIG. 13B is a graph showing changes in the intensity of the detection signals te1 and te2 from the light receiving elements 120b and 120c for tracking. FIG. 13C is a graph showing a change in intensity of the tracking signal TE, which is the difference between the detection signal te1 and the detection signal te2 output from the operational amplifier 111.
　金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、微粒子１０２と相互作用し、微粒子１０２と一体となってプラズモン共鳴する。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃと微粒子１０２との共鳴状態は、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃ及び微粒子１０２の設計によって変化する。このため、設計次第で、プラズモン共鳴により金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度が増加する場合もあれば、プラズモン共鳴により金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度が減少する場合もある。本実施の形態２では、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度が微粒子１０２との共鳴により減少する場合を一例として示している。 The metal antennas 128 a, 128 b and 128 c interact with the fine particles 102 and plasmon resonate together with the fine particles 102. The resonance state between the metal antennas 128a, 128b, and 128c and the fine particles 102 varies depending on the design of the metal antennas 128a, 128b, and 128c and the fine particles 102. For this reason, depending on the design, the reflected light intensity from the metal antennas 128a, 128b, and 128c may increase due to plasmon resonance, or the reflected light intensity from the metal antennas 128a, 128b, and 128c may decrease due to plasmon resonance. is there. In the second embodiment, the case where the reflected light intensity from the metal antennas 128a, 128b, and 128c decreases due to resonance with the fine particles 102 is shown as an example.
　プラズモン共鳴の共鳴状態は、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃと微粒子１０２との距離に敏感に反応する。このため、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度は、図１３（Ａ）に示すように、トラック位置（トラック１１２からの距離がトラッキング周期Ｔｐと一致する位置）で最小となり、トラック１１２からの距離がトラッキング周期Ｔｐの半分となる位置で最大となる。 The resonance state of plasmon resonance reacts sensitively to the distance between the metal antennas 128a, 128b and 128c and the fine particles 102. For this reason, the reflected light intensity from the metal antennas 128a, 128b and 128c is minimized at the track position (position where the distance from the track 112 coincides with the tracking period Tp) as shown in FIG. Is the maximum at a position where the distance from is half the tracking period Tp.
　受光素子１２０ｂ及び１２０ｃの検出信号ｔｅ１及びｔｅ２は、トラッキング信号演算回路として機能するオペアンプ１１１に入力される。オペアンプ１１１は、検出信号ｔｅ１と検出信号ｔｅ２との差をトラッキング信号ＴＥとして出力する。このように、トラッキング信号演算回路であるオペアンプ１１１は、複数の共鳴素子（金属アンテナ１２８ｂ及び１２８ｃ）の各々の共鳴状態の変化に基づいてトラッキング信号ＴＥを得る。 The detection signals te1 and te2 of the light receiving elements 120b and 120c are input to the operational amplifier 111 that functions as a tracking signal calculation circuit. The operational amplifier 111 outputs the difference between the detection signal te1 and the detection signal te2 as the tracking signal TE. As described above, the operational amplifier 111 serving as the tracking signal calculation circuit obtains the tracking signal TE based on the change in the resonance state of each of the plurality of resonance elements ( metal antennas 128b and 128c).
　本実施の形態２では、トラッキング用の金属アンテナ１２８ｂ及び１２８ｃは、記録又は再生用の金属アンテナ１２８ａに対してそれぞれトラック１１２に垂直な方向に、トラッキング周期Ｔｐの４分の１だけ離して設置されている。そのため、図１３（Ｂ）及び図１３（Ｃ）に示すように、検出信号ｔｅ１と検出信号ｔｅ２との差を最大にすることができ、高精度なトラッキング信号ＴＥを得ることができる。 In the second embodiment, the tracking metal antennas 128b and 128c are set apart from the recording or reproducing metal antenna 128a by a quarter of the tracking period Tp in the direction perpendicular to the track 112, respectively. ing. Therefore, as shown in FIGS. 13B and 13C, the difference between the detection signal te1 and the detection signal te2 can be maximized, and a highly accurate tracking signal TE can be obtained.
　出力されたトラッキング信号ＴＥはアクチュエータ１０６に入力される。アクチュエータ１０６は、トラッキング信号ＴＥに対応してスライダ１２４をトラック１１２に垂直な方向に駆動する。かかる構成により、記録又は再生用の金属アンテナ１２８ａを微粒子１０２に対して、安定かつ高精度にトラッキングすることができる。 The output tracking signal TE is input to the actuator 106. The actuator 106 drives the slider 124 in a direction perpendicular to the track 112 in response to the tracking signal TE. With this configuration, the recording or reproducing metal antenna 128a can be stably and accurately tracked with respect to the fine particles 102.
　なお、本実施の形態２において、金属アンテナ１２８ｂ，１２８ｃが複数の共鳴素子の一例に相当し、スライダ１２４が保持素子の一例に相当し、受光素子１２０ｂ，１２０ｃが第１の検出素子及び複数の受光素子の一例に相当し、サスペンション１２５が第２の移動素子の一例に相当し、導波路１２９ｂ，１２９ｃが複数の導波路の一例に相当する。 In the second embodiment, the metal antennas 128b and 128c correspond to an example of a plurality of resonance elements, the slider 124 corresponds to an example of a holding element, and the light receiving elements 120b and 120c include the first detection element and the plurality of resonance elements. The suspension 125 corresponds to an example of a light receiving element, the suspension 125 corresponds to an example of a second moving element, and the waveguides 129b and 129c correspond to an example of a plurality of waveguides.
　このように、本実施の形態２では、ハードディスクドライブに採用されるフライングヘッドと同様の技術を用いている。これにより、スライダ１２４とディスク１０１とが接触することなく、スライダ１２４は、ディスク１０１上の数ｎｍ～数十ｎｍの位置においてディスク１０１を走査することができる。そのため、ディスク１０１及びスライダ１２４がそれぞれ磨耗を起こさずに精密なギャップ制御を行うことができる。 Thus, in the second embodiment, the same technology as that of the flying head employed in the hard disk drive is used. Thus, the slider 124 can scan the disk 101 at a position of several nm to several tens of nm on the disk 101 without the slider 124 and the disk 101 coming into contact with each other. Therefore, precise gap control can be performed without causing the disk 101 and the slider 124 to wear.
　また、本実施の形態２では、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、それぞれトラックの長手方向にずらして配置される。すなわち、スライダ１２４は、金属アンテナ１２８ｂ及び１２８ｃの位置をトラックの長手方向にずらして配置する。これにより、隣接する金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの間の相互作用を抑制でき、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの形状の自由度が高くなる。 In the second embodiment, the metal antennas 128a, 128b, and 128c are arranged so as to be shifted in the longitudinal direction of the track. That is, the slider 124 is arranged by shifting the positions of the metal antennas 128b and 128c in the longitudinal direction of the track. Thereby, the interaction between the adjacent metal antennas 128a, 128b, and 128c can be suppressed, and the degree of freedom of the shape of the metal antennas 128a, 128b, and 128c is increased.
　さらに、光源（半導体レーザ素子１０７ｂ及び１０７ｃ）から複数の共鳴素子（金属アンテナ１２８ｂ及び１２８ｃ）に入射する入射光の偏光方向は、ディスク１０１の表面に垂直な方向であることが好ましい。また、複数の共鳴素子（金属アンテナ１２８ｂ及び金属アンテナ１２８ｃ）のトラックの長手方向の位置は、複数の共鳴素子（金属アンテナ１２８ｂ又は１２８ｃ）のうちの１つの共鳴素子のトラックの長手方向の厚さ以上にずれていても良い。これにより、複数の共鳴素子間の相互作用をより抑制できる。 Furthermore, it is preferable that the polarization direction of incident light incident on the plurality of resonant elements ( metal antennas 128 b and 128 c) from the light source ( semiconductor laser elements 107 b and 107 c) is a direction perpendicular to the surface of the disk 101. Also, the longitudinal position of the track of the plurality of resonance elements (metal antenna 128b and metal antenna 128c) is the thickness in the longitudinal direction of the track of one resonance element of the plurality of resonance elements ( metal antenna 128b or 128c). It may be shifted as described above. Thereby, the interaction between a plurality of resonant elements can be further suppressed.
　さらに、本実施の形態２では、近接場光ではなく反射光が検出される。これにより、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの直近に微小な受光素子１１０ａ、１１０ｂ及び１１０ｃを作製する必要がなくなり、光情報装置の作製が容易になる。 Furthermore, in the second embodiment, reflected light is detected instead of near-field light. This eliminates the need to fabricate minute light receiving elements 110a, 110b, and 110c in the immediate vicinity of the metal antennas 128a, 128b, and 128c, and facilitates fabrication of the optical information device.
　また、本実施の形態２では、受光素子１２０ａ、１２０ｂ及び１２０ｃは、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃと相互作用することがない。このため、効率よく金属アンテナ１２８ａ、１２８ｂ及び１２８ｃとディスク１０１とを相互作用させることができ、効率よくトラッキング及び情報の記録又は再生を行うことができる。 In the second embodiment, the light receiving elements 120a, 120b, and 120c do not interact with the metal antennas 128a, 128b, and 128c. For this reason, the metal antennas 128a, 128b, and 128c and the disk 101 can be efficiently interacted, and tracking and information recording or reproduction can be performed efficiently.
　なお、本実施の形態２では、半導体レーザ素子及び受光素子のペアが、１本の導波路に対して隣接して配置されているが、例えば、Ｙ字導波路を用いてもよい。この場合、Ｙ字導波路の一方に半導体レーザ素子を配置し、他方に受光素子を配置してもよい。このように、光の出射位置と反射光の検出位置とを分離する構成にしても、本発明の主旨が損なわれるものではない。 In the second embodiment, a pair of a semiconductor laser element and a light receiving element is disposed adjacent to one waveguide, but for example, a Y-shaped waveguide may be used. In this case, a semiconductor laser element may be disposed on one side of the Y-shaped waveguide, and a light receiving element may be disposed on the other side. Thus, even if it is the structure which isolate | separates the light emission position and the detection position of reflected light, the main point of this invention is not impaired.
　また、本実施の形態２では、スライダ１２４の端面に階段状の段差が形成され、各段に金属アンテナ１２８ａ、１２８ｂ及び１２８ｃが配置されているが、本発明は特にこれに限定されない。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、互いに相互作用しないように、トラックの長手方向にずれて配置されていればよい。図１４は、本発明の実施の形態２の第１の変形例におけるスライダを示す上面図であり、図１５は、本発明の実施の形態２の第２の変形例におけるスライダを示す上面図である。例えば、図１４又は図１５に示すように、スライダ１２４の端面は、凸形状又は凹形状であってもよい。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、トラックの長手方向にずれて配置される。 In the second embodiment, a stepped step is formed on the end surface of the slider 124, and the metal antennas 128a, 128b, and 128c are arranged on each step. However, the present invention is not particularly limited to this. The metal antennas 128a, 128b, and 128c only need to be shifted in the longitudinal direction of the track so as not to interact with each other. FIG. 14 is a top view showing the slider in the first modification of the second embodiment of the present invention, and FIG. 15 is a top view showing the slider in the second modification of the second embodiment of the present invention. is there. For example, as shown in FIG. 14 or FIG. 15, the end surface of the slider 124 may be convex or concave. The metal antennas 128a, 128b and 128c are arranged so as to be shifted in the longitudinal direction of the track.
　また、本実施の形態２では、スライダ１２４とエアスライダ１３２とは別々の構成としているが、本発明は特にこれに限定されず、スライダ１２４を大きくしてもよい。スライダ１２４は、ディスク１０１の表面に垂直な方向にスライダ１２４を移動させるエアスライダの機能を兼ね備えてもよい。この場合も、本発明の主旨が損なわれるものではない。 In the second embodiment, the slider 124 and the air slider 132 are configured separately, but the present invention is not particularly limited to this, and the slider 124 may be enlarged. The slider 124 may also have the function of an air slider that moves the slider 124 in a direction perpendicular to the surface of the disk 101. Also in this case, the gist of the present invention is not impaired.
　また、実施の形態１及び２では、アクチュエータ１０６でサスペンション１０５（又は１２５）をトラックに垂直な方向に駆動する構成としているが、本発明は特にこれに限定されない。図１６は、本発明の実施の形態１及び２の変形例におけるスライダの構成を示す図である。図１６に示すように、光情報装置は、実施の形態１及び２のアクチュエータ１０６の代わりにモータ１１６を備える。モータ１１６は、ディスク１０１の表面に平行な面内において、当該モータ１１６を中心としてサスペンション１０５（１２５）を回転させる。このように、モータ１１６は、サスペンション１０５（又は１２５）をアームとして回転させ、ハードディスクドライブのようにスライダ１０４（又は１２４）をトラックに垂直な方向に駆動してもよい。 In the first and second embodiments, the suspension 105 (or 125) is driven in the direction perpendicular to the track by the actuator 106, but the present invention is not particularly limited to this. FIG. 16 is a diagram showing a configuration of a slider in a modification of the first and second embodiments of the present invention. As shown in FIG. 16, the optical information apparatus includes a motor 116 instead of the actuator 106 according to the first and second embodiments. The motor 116 rotates the suspension 105 (125) around the motor 116 in a plane parallel to the surface of the disk 101. As described above, the motor 116 may rotate the suspension 105 (or 125) as an arm and drive the slider 104 (or 124) in a direction perpendicular to the track like a hard disk drive.
　また、実施の形態１及び２では、情報を記録又は再生するために相変化材料で構成された微粒子を用いているが、本発明は特にこれに限定されない。光情報装置が、例えばＲＯＭ（Ｒｅａｄ　Ｏｎｌｙ　Ｍｅｍｏｒｙ）装置のような再生のみを行う光情報装置である場合は、微粒子の代わりに、凹凸形状のピットを用いてもよく、又は金属パターンなどを用いてもよい。 In Embodiments 1 and 2, fine particles composed of a phase change material are used for recording or reproducing information, but the present invention is not particularly limited to this. When the optical information device is an optical information device that performs only reproduction, such as a ROM (Read Only Memory) device, for example, an uneven pit may be used instead of fine particles, or a metal pattern or the like may be used. Also good.
　また、実施の形態１及び２では、金属アンテナの形状は三角平板形状であるが、金属アンテナの形状は上記の例に特に限定されず、例えば三角平板形状以外にも図１７～図１９に示すような形状も考えられる。金属アンテナの形状は、微粒子上でプラズモン共鳴し、トラックからの距離に応じて効率よくプラズモン共鳴状態が変化するものであれば、特に限定されるものではない。 In Embodiments 1 and 2, the shape of the metal antenna is a triangular plate shape. However, the shape of the metal antenna is not particularly limited to the above example, and examples other than the triangular plate shape are shown in FIGS. Such a shape is also conceivable. The shape of the metal antenna is not particularly limited as long as plasmon resonance occurs on the fine particles and the plasmon resonance state efficiently changes according to the distance from the track.
　図１７は、本発明の実施の形態１及び２において、四角平板形状である金属アンテナを示す図であり、図１８は、本発明の実施の形態１及び２において、円板形状である金属アンテナを示す図であり、図１９は、本発明の実施の形態１及び２において、プローブ形状である金属アンテナを示す図である。 FIG. 17 is a diagram showing a metal antenna having a square plate shape in the first and second embodiments of the present invention, and FIG. 18 is a metal antenna having a disk shape in the first and second embodiments of the present invention. FIG. 19 is a diagram showing a metal antenna having a probe shape in the first and second embodiments of the present invention.
　図１７のように、金属アンテナ１１７の形状が四角平板形状である場合、金属アンテナ１１７は上下対称であるため三角平板形状と比較して解析が容易である。また、図１８のように、金属アンテナ１１８の形状が円板形状である場合、パターンの作製が三角平板形状に比べて容易である。また、図１９のように、金属アンテナ１１９の形状がプローブ形状である場合、より効率的にプローブの先端に近接場光を発生させることができる。 As shown in FIG. 17, when the shape of the metal antenna 117 is a rectangular flat plate shape, the metal antenna 117 is vertically symmetric, so that the analysis is easier than the triangular flat plate shape. Further, as shown in FIG. 18, when the shape of the metal antenna 118 is a disc shape, the pattern can be easily produced as compared with the triangular plate shape. Further, as shown in FIG. 19, when the shape of the metal antenna 119 is a probe shape, near-field light can be generated more efficiently at the tip of the probe.
　また、実施の形態１及び２では、２つのトラッキング用の金属アンテナを備え、当該２つの金属アンテナは、トラックに垂直な方向にトラッキング周期Ｔｐの２分の１だけずらして配置される。しかしながら、金属アンテナの本数及び配置方法は、トラック位置において複数のトラッキング用の金属アンテナからの検出信号の差が０となり、トラックからの位置ずれに応じて検出信号の差が得られるものであればよい。トラッキング用の金属アンテナの本数及び配置方法は、本実施の形態１及び２として示した構成に特に限定されるものではない。 In the first and second embodiments, two tracking metal antennas are provided, and the two metal antennas are arranged so as to be shifted by a half of the tracking period Tp in a direction perpendicular to the track. However, as long as the number of metal antennas and the arrangement method are such that the difference in detection signals from a plurality of metal antennas for tracking is zero at the track position and the difference in detection signals can be obtained according to the positional deviation from the track. Good. The number of metal antennas for tracking and the arrangement method are not particularly limited to the configurations shown as the first and second embodiments.
　また、実施の形態１及び２では、導波モード結合を抑制するために複数の導波路１０９ａ～１０９ｃ（１２９ａ～１２９ｃ）は互いに非平行に配置されるが、導波モード結合が起こらない構成であれば、複数の導波路１０９ａ～１０９ｃ（１２９ａ～１２９ｃ）は互いに平行に配置してもよく、これにより、本発明の主旨が損なわれるものではない。 In the first and second embodiments, the plurality of waveguides 109a to 109c (129a to 129c) are arranged non-parallel to each other in order to suppress the waveguide mode coupling. However, the waveguide mode coupling does not occur. If so, the plurality of waveguides 109a to 109c (129a to 129c) may be arranged in parallel to each other, and this does not impair the gist of the present invention.
　また、実施の形態１及び２では、半導体レーザ素子１０７ａ～１０７ｃ、金属アンテナ１０８ａ～１０８ｃ（１２８ａ～１２８ｃ）及び受光素子１１０ａ～１１０ｃ（１２０ａ～１２０ｃ）はスライダ１０４（１２４）の端面に配置されるが、本発明は特にこれに限定されない。スライダ１０４（１２４）の上面又はスライダ１０４（１２４）の内部にこれらの素子を配置したり、ワンチップにこれらの素子を集積化して作製したりしてもよい。 In the first and second embodiments, the semiconductor laser elements 107a to 107c, the metal antennas 108a to 108c (128a to 128c), and the light receiving elements 110a to 110c (120a to 120c) are disposed on the end face of the slider 104 (124). However, the present invention is not particularly limited to this. These elements may be arranged on the upper surface of the slider 104 (124) or inside the slider 104 (124), or these elements may be integrated on a single chip.
　また、実施の形態１及び２では、光情報装置は、３つの光源（半導体レーザ素子１０７ａ～１０７ｃ）を備えているが、光情報装置は、１つの光源を備え、１つの光源からの光を導波路により３方向に分離して、金属アンテナに光を入射させてもよい。また、光情報装置は、記録又は再生用の光源とトラッキング用の光源とを１つずつ備え、トラッキング用の光源のみからの光をＹ字導波路で２方向に分離して、２つの金属アンテナに光を入射させてもよい。これらにより、本発明の主旨が損なわれるものではない。 In the first and second embodiments, the optical information device includes three light sources (semiconductor laser elements 107a to 107c). However, the optical information device includes one light source and emits light from one light source. The light may be incident on the metal antenna after being separated in three directions by a waveguide. Further, the optical information device includes one light source for recording or reproduction and one light source for tracking, and separates light from only the light source for tracking in two directions by a Y-shaped waveguide, thereby providing two metal antennas. Light may be incident on. These do not impair the gist of the present invention.
　（実施の形態３）
　次に、本発明の実施の形態３における光情報装置について説明する。 (Embodiment 3)
Next, an optical information device according to Embodiment 3 of the present invention will be described.
　図２０は、本発明の実施の形態３における光情報装置の構成を示す概略図である。図２１は、図２０に示す複数の金属アンテナの構成を示す斜視図であり、図２２は、図２０に示す複数の金属アンテナの構成を示す上面図である。図２０～図２２において、図１～図４と同じ構成要素については同じ符号を用い、説明を省略する。 FIG. 20 is a schematic diagram showing the configuration of the optical information device according to the third embodiment of the present invention. 21 is a perspective view showing the configuration of the plurality of metal antennas shown in FIG. 20, and FIG. 22 is a top view showing the configuration of the plurality of metal antennas shown in FIG. 20 to 22, the same components as those in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof is omitted.
　図２０において、光情報装置は、半導体レーザ素子２０２ａ，２０２ｂ，２０２ｃ，２０２ｄ、金属アンテナ２２８ａ，２２８ｂ，２２８ｃ、レンズ２０３，２０４，２０５，２０６，２０７、ハーフミラー２０８，２０９、ダイクロイックミラー２１０、４分の１波長板２１１、検光子２１２、遮光板２１３、回折格子２１４、受光素子２１５ａ，２１５ｂ，２１５ｃ，２１５ｄ、ソリッドイマージョンレンズ２１６、レンズホルダ２１７、アクチュエータ２１８及びオペアンプ１１１を備える。 20, the optical information device includes semiconductor laser elements 202a, 202b, 202c, 202d, metal antennas 228a, 228b, 228c, lenses 203, 204, 205, 206, 207, half mirrors 208, 209, dichroic mirrors 210, 4 A half-wave plate 211, an analyzer 212, a light shielding plate 213, a diffraction grating 214, light receiving elements 215a, 215b, 215c, and 215d, a solid immersion lens 216, a lens holder 217, an actuator 218, and an operational amplifier 111 are provided.
　図２０において、ディスク２２１は、情報が列状に記録されたトラックを有する情報記録媒体である。ディスク２２１には、トラックとして機能するグルーブ２０１が形成されており、情報は、グルーブ２０１上に記録されている。 In FIG. 20, a disk 221 is an information recording medium having tracks on which information is recorded in a line. A groove 201 functioning as a track is formed on the disk 221, and information is recorded on the groove 201.
　半導体レーザ素子２０２ａ、２０２ｂ、２０２ｃ及び２０２ｄの出力波長は、それぞれ異なっている。本実施の形態３では、半導体レーザ素子２０２ａ、２０２ｂ、２０２ｃ及び２０２ｄは、それぞれ例えば７８０ｎｍ、６３０ｎｍ、８３０ｎｍ及び４００ｎｍの波長の光を出射する。半導体レーザ素子２０２ａ、２０２ｂ、２０２ｃ及び２０２ｄからの光の偏光は直線偏光である。半導体レーザ素子２０２ａは、情報を記録又は再生するための光源として用いられ、半導体レーザ素子２０２ｂ及び２０２ｃは、トラッキング用の光源として用いられ、半導体レーザ素子２０２ｄは、ギャップ検出用の光源として用いられる。 The output wavelengths of the semiconductor laser elements 202a, 202b, 202c and 202d are different from each other. In the third embodiment, the semiconductor laser elements 202a, 202b, 202c, and 202d emit light having wavelengths of 780 nm, 630 nm, 830 nm, and 400 nm, respectively. The polarization of light from the semiconductor laser elements 202a, 202b, 202c and 202d is linearly polarized light. The semiconductor laser element 202a is used as a light source for recording or reproducing information, the semiconductor laser elements 202b and 202c are used as light sources for tracking, and the semiconductor laser element 202d is used as a light source for gap detection.
　金属アンテナ２２８ａ、２２８ｂ及び２２８ｃは、それぞれ半導体レーザ素子２０２ａ、２０２ｂ及び２０２ｃからの光によりプラズモン共鳴を励起する共鳴素子である。金属アンテナ２２８ａ、２２８ｂ及び２２８ｃは、例えば金、銀、銅、チタン、アルミ又はクロムなどの材料で構成される。また、図２１に示すように、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃの形状は、三角平板形状である。金属アンテナ２２８ａ、２２８ｂ及び２２８ｃは、三角形状の面がディスク２２１の表面に平行になるように配置されている。金属アンテナ２２８ａ、２２８ｂ及び２２８ｃには、偏光方向が、ディスク２２１の表面に平行であり、かつトラックの長手方向に平行である光が入射する。これにより、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃにおいてプラズモン共鳴が励起され、三角形の頂点近傍に強い近接場光が発生する。 The metal antennas 228a, 228b, and 228c are resonance elements that excite plasmon resonance by light from the semiconductor laser elements 202a, 202b, and 202c, respectively. The metal antennas 228a, 228b, and 228c are made of a material such as gold, silver, copper, titanium, aluminum, or chromium. Further, as shown in FIG. 21, the metal antennas 228a, 228b, and 228c have a triangular flat plate shape. The metal antennas 228 a, 228 b, and 228 c are arranged so that the triangular surface is parallel to the surface of the disk 221. Light having a polarization direction parallel to the surface of the disk 221 and parallel to the longitudinal direction of the track is incident on the metal antennas 228a, 228b, and 228c. As a result, plasmon resonance is excited in the metal antennas 228a, 228b, and 228c, and strong near-field light is generated near the apex of the triangle.
　共鳴素子である金属アンテナ２２８ｂ及び２２８ｃは、ディスク２２１と相互作用し、トラック（グルーブ２０１）からの距離に応じて、共鳴状態が変化する。金属アンテナ２２８ａ、２２８ｂ及び２２８ｃは、それぞれ半導体レーザ素子２０２ａ、２０２ｂ及び２０２ｃからの出射光に対してトラック中心上で最大のプラズモン共鳴が得られるように、それぞれ形状又は材質が異なる。 The metal antennas 228b and 228c, which are resonance elements, interact with the disk 221, and the resonance state changes according to the distance from the track (groove 201). The metal antennas 228a, 228b and 228c have different shapes or materials so that the maximum plasmon resonance can be obtained on the track center with respect to the light emitted from the semiconductor laser elements 202a, 202b and 202c, respectively.
　また、図２２に示すように、トラッキング用の金属アンテナ２２８ｂ及び２２８ｃは、記録又は再生用の金属アンテナ２２８ａを中心にして、トラックに垂直な方向に位置をずらして配置される。金属アンテナ２２８ｂ及び２２８ｃは、金属アンテナ２２８ａからトラック１１２に垂直な方向にそれぞれ距離Ｐだけ離れた位置に配置される。距離Ｐは、トラッキング周期（トラックピッチ）Ｔｐの４分の１である。このとき、金属アンテナ２２８ｂと金属アンテナ２２８ｃとの間のトラックに垂直な方向の距離（２Ｐ）は、トラッキング周期Ｔｐの２分の１に固定される。 Also, as shown in FIG. 22, the tracking metal antennas 228b and 228c are arranged with their positions shifted in the direction perpendicular to the track with the recording or reproduction metal antenna 228a as the center. The metal antennas 228b and 228c are disposed at positions separated from the metal antenna 228a by a distance P in a direction perpendicular to the track 112, respectively. The distance P is a quarter of the tracking period (track pitch) Tp. At this time, the distance (2P) in the direction perpendicular to the track between the metal antenna 228b and the metal antenna 228c is fixed to one half of the tracking period Tp.
　一方、金属アンテナ２２８ａ及び２２８ｂは、複数の金属アンテナが互いに相互作用することを避けるために金属アンテナ２２８ａの頂点と金属アンテナ２２８ｂの底辺とがトラックの長手方向に重ならないように、トラックの長手方向にずらして配置されている。同様に、金属アンテナ２２８ａ及び２２８ｃは、金属アンテナ２２８ａの底辺と金属アンテナ２２８ｃの頂点とがトラックの長手方向に重ならないように、トラックの長手方向にずらして配置されている。半導体レーザ素子２０２ａ、２０２ｂ及び２０２ｃの偏光方向は、共鳴周波数の異なる共鳴素子として機能する金属アンテナ２２８ａ、２２８ｂ及び２２８ｃの共鳴方向と一致するようにする。 On the other hand, the metal antennas 228a and 228b are arranged so that the apex of the metal antenna 228a and the base of the metal antenna 228b do not overlap with the longitudinal direction of the track in order to avoid a plurality of metal antennas from interacting with each other. It is arranged to shift to. Similarly, the metal antennas 228a and 228c are arranged so as to be shifted in the longitudinal direction of the track so that the bottom of the metal antenna 228a and the apex of the metal antenna 228c do not overlap with the longitudinal direction of the track. The polarization directions of the semiconductor laser elements 202a, 202b, and 202c are made to coincide with the resonance directions of the metal antennas 228a, 228b, and 228c that function as resonance elements having different resonance frequencies.
　以上のように、本実施の形態３の光情報装置においては、光源（半導体レーザ素子２０２ｂ及び２０２ｃ）から複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）に入射する入射光の偏光方向は、ディスク２２１の表面に対して平行な方向かつトラックに対して平行な方向である。このとき、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）の間のトラックの長手方向の位置は、複数の共鳴素子のうちの１つの共鳴素子のトラックの長手方向の長さ以上にずれている。 As described above, in the optical information device according to the third embodiment, the polarization direction of incident light incident on the plurality of resonance elements ( metal antennas 228b and 228c) from the light source ( semiconductor laser elements 202b and 202c) is the disk 221. The direction parallel to the surface of the track and the direction parallel to the track. At this time, the position in the longitudinal direction of the track between the plurality of resonance elements ( metal antennas 228b and 228c) is shifted more than the length in the longitudinal direction of the track of one resonance element of the plurality of resonance elements.
　また、図２０において、ダイクロイックミラー２１０は、波長５００ｎｍ以下の光を反射する。４分の１波長板２１１は、半導体レーザ素子２０２ｄからの光に対し、直線偏光を円偏光に変換する。検光子２１２は、半導体レーザ素子２０２ｄからの光の偏光方向と同じ偏光方向の光を透過する。遮光板２１３は、中央部分の光を遮光して周辺部分の光のみを透過する。回折格子２１４は、金属アンテナ２２８ａからの反射光を受光素子２１５ａへ回折させ、金属アンテナ２２８ｂからの反射光を受光素子２１５ｂへ回折させ、金属アンテナ２２８ｃからの反射光を受光素子２１５ｃへ回折させる。 In FIG. 20, the dichroic mirror 210 reflects light having a wavelength of 500 nm or less. The quarter-wave plate 211 converts linearly polarized light into circularly polarized light with respect to the light from the semiconductor laser element 202d. The analyzer 212 transmits light having the same polarization direction as that of the light from the semiconductor laser element 202d. The light shielding plate 213 shields light at the central portion and transmits only light at the peripheral portion. The diffraction grating 214 diffracts the reflected light from the metal antenna 228a to the light receiving element 215a, diffracts the reflected light from the metal antenna 228b to the light receiving element 215b, and diffracts the reflected light from the metal antenna 228c to the light receiving element 215c.
　受光素子２１５ａ、２１５ｂ及び２１５ｃは金属アンテナ２２８ａ、２２８ｂ及び２２８ｃの各々の共鳴状態の変化を個別に検出して、検出信号を出力する。受光素子２１５ａ、２１５ｂ及び２１５ｃは、それぞれ金属アンテナ２２８ａ、２２８ｂ及び２２８ｃからの散乱光を個別に検出する。 The light receiving elements 215a, 215b, and 215c individually detect changes in the resonance states of the metal antennas 228a, 228b, and 228c, and output detection signals. The light receiving elements 215a, 215b and 215c individually detect scattered light from the metal antennas 228a, 228b and 228c, respectively.
　受光素子２１５ｄは、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃと、ディスク２２１との距離を検出する。受光素子２１５ｄは、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃと、ディスク２２１との距離を表すギャップ信号ＧＴを出力する。 The light receiving element 215d detects the distance between the metal antennas 228a, 228b and 228c and the disk 221. The light receiving element 215d outputs a gap signal GT indicating the distance between the metal antennas 228a, 228b, and 228c and the disk 221.
　ソリッドイマージョンレンズ２１６の底面には、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃが形成される。ソリッドイマージョンレンズ２１６は、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃを保持する保持素子として機能する。保持素子であるソリッドイマージョンレンズ２１６は、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）の位置を、トラックに垂直な方向にずらして配置し、かつ複数の共鳴素子間の距離を一定に固定して保持する。 Metal antennas 228a, 228b and 228c are formed on the bottom surface of the solid immersion lens 216. The solid immersion lens 216 functions as a holding element that holds the metal antennas 228a, 228b, and 228c. The solid immersion lens 216, which is a holding element, is arranged by shifting the positions of a plurality of resonance elements ( metal antennas 228b and 228c) in a direction perpendicular to the track and fixing the distance between the plurality of resonance elements constant. Hold.
　レンズホルダ２１７は、ソリッドイマージョンレンズ２１６及びレンズ２０７を保持し、ソリッドイマージョンレンズ２１６とレンズ２０７との位置を相対的に固定する。 The lens holder 217 holds the solid immersion lens 216 and the lens 207, and relatively fixes the positions of the solid immersion lens 216 and the lens 207.
　アクチュエータ２１８は、受光素子２１５ｄから出力されたギャップ信号ＧＴ及びオペアンプ１１１から出力されたトラッキング信号ＴＥに基づいて、レンズホルダ２１７をトラックに垂直な方向及びディスク２２１の表面に垂直な方向に移動させる。すなわち、第１の移動素子であるアクチュエータ２１８は、トラッキング信号ＴＥに応じて保持素子（ソリッドイマージョンレンズ２１６）をトラックに垂直な方向に移動させる。また、アクチュエータ２１８は、受光素子２１５ｄからの検出信号（ギャップ信号ＧＴ）に応じて、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）とディスク２２１との間の距離が一定になるように、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）をディスク２２１の表面に垂直な方向に移動させる。 The actuator 218 moves the lens holder 217 in the direction perpendicular to the track and the direction perpendicular to the surface of the disk 221 based on the gap signal GT output from the light receiving element 215d and the tracking signal TE output from the operational amplifier 111. That is, the actuator 218 as the first moving element moves the holding element (solid immersion lens 216) in a direction perpendicular to the track in accordance with the tracking signal TE. In addition, the actuator 218 has a plurality of resonance elements ( metal antennas 228b and 228c) and a plurality of the plurality of resonance elements ( metal antennas 228b and 228c) so that the distance between the disk 221 is constant according to the detection signal (gap signal GT) from the light receiving element 215d. The resonant elements ( metal antennas 228b and 228c) are moved in a direction perpendicular to the surface of the disk 221.
　本実施の形態３においては、レンズ２０４、ハーフミラー２０９及びレンズ２０７などが、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）に、光源（半導体レーザ素子２０２ｂ及び２０２ｃ）からの光を導く光学素子として機能する。 In the third embodiment, the lens 204, the half mirror 209, the lens 207, and the like are optical elements that guide light from the light sources ( semiconductor laser elements 202b and 202c) to a plurality of resonance elements ( metal antennas 228b and 228c). Function.
　なお、本実施の形態３において、ディスク２２１が情報記録媒体の一例に相当し、半導体レーザ素子２０２ｂ，２０２ｃが光源及び複数の光源の一例に相当し、金属アンテナ２２８ｂ，２２８ｃが複数の共鳴素子の一例に相当し、ソリッドイマージョンレンズ２１６が保持素子の一例に相当し、受光素子２１５ｂ，２１５ｃが第１の検出素子及び複数の受光素子の一例に相当し、アクチュエータ２１８が第１の移動素子及び第２の移動素子の一例に相当し、受光素子２１５ｄが第２の検出素子の一例に相当し、回折格子２１４が光学素子の一例に相当する。 In the third embodiment, the disk 221 corresponds to an example of an information recording medium, the semiconductor laser elements 202b and 202c correspond to examples of a light source and a plurality of light sources, and the metal antennas 228b and 228c include a plurality of resonance elements. The solid immersion lens 216 corresponds to an example of a holding element, the light receiving elements 215b and 215c correspond to an example of a first detection element and a plurality of light receiving elements, and the actuator 218 corresponds to an example of a first moving element and a first moving element. The light receiving element 215d corresponds to an example of a second detection element, and the diffraction grating 214 corresponds to an example of an optical element.
　ここで、本実施の形態３における光情報装置の動作について説明する。まず、本実施の形態３における光情報装置のギャップ検出方法について説明する。 Here, the operation of the optical information apparatus in the third embodiment will be described. First, the gap detection method of the optical information device in the third embodiment will be described.
　半導体レーザ素子２０２ｄから出射された光は、レンズ２０３によりコリメートされ、ハーフミラー２０８を透過する。ハーフミラー２０８を透過した光は、４分の１波長板２１１により円偏光に変換され、ダイクロイックミラー２１０により反射される。ダイクロイックミラー２１０により反射された光は、レンズ２０７とソリッドイマージョンレンズ２１６とにより集光される。 The light emitted from the semiconductor laser element 202d is collimated by the lens 203 and passes through the half mirror 208. The light transmitted through the half mirror 208 is converted into circularly polarized light by the quarter wave plate 211 and reflected by the dichroic mirror 210. The light reflected by the dichroic mirror 210 is collected by the lens 207 and the solid immersion lens 216.
　ディスク２２１とソリッドイマージョンレンズ２１６との間の距離が遠い場合には、開口数ＮＡの高い成分の光は、ソリッドイマージョンレンズ２１６の底面で全反射される。ソリッドイマージョンレンズ２１６の底面で全反射された光は、レンズ２０７を透過した後、ダイクロイックミラー２１０で反射され、再び４分の１波長板２１１を透過する。全反射された光は、全反射前に比べて、反射面に垂直な偏光の光と反射面に平行な偏光の光との位相がずれる。そのため、再び４分の１波長板２１１を透過した光は、半導体レーザ素子２０２ｄの出射光と同じ偏光の光を含む。４分の１波長板２１１を透過した光は、ハーフミラー２０８で反射され、検光子２１２によって半導体レーザ素子２０２ｄの出射光と同じ偏光の光だけが透過され、レンズ２０５により受光素子２１５ｄに集光される。 When the distance between the disk 221 and the solid immersion lens 216 is long, the component light having a high numerical aperture NA is totally reflected on the bottom surface of the solid immersion lens 216. The light totally reflected by the bottom surface of the solid immersion lens 216 is transmitted through the lens 207, is reflected by the dichroic mirror 210, and is transmitted through the quarter-wave plate 211 again. Totally reflected light is out of phase with polarized light perpendicular to the reflecting surface and polarized light parallel to the reflecting surface as compared to before total reflection. Therefore, the light transmitted through the quarter-wave plate 211 again includes light having the same polarization as the light emitted from the semiconductor laser element 202d. The light transmitted through the quarter-wave plate 211 is reflected by the half mirror 208, and only the light having the same polarization as that emitted from the semiconductor laser element 202 d is transmitted by the analyzer 212, and condensed by the lens 205 onto the light receiving element 215 d. Is done.
　一方、全反射ではない反射によりソリッドイマージョンレンズ２１６の底面で反射されて戻ってくる開口数ＮＡの低い成分の光は、反射面に垂直な偏光の光と反射面に平行な偏光の光との位相差が変化しない。そのため、４分の１波長板２１１を２度透過した光の偏光方向は、半導体レーザ素子２０２ｄから出射された光の偏光方向に対して９０度傾いた状態になる。その結果、４分の１波長板２１１を透過した光は、検光子２１２により遮光される。 On the other hand, light with a component having a low numerical aperture NA, which is reflected by the bottom surface of the solid immersion lens 216 due to reflection that is not total reflection, returns between polarized light perpendicular to the reflecting surface and polarized light parallel to the reflecting surface. The phase difference does not change. Therefore, the polarization direction of the light transmitted through the quarter-wave plate 211 twice is inclined by 90 degrees with respect to the polarization direction of the light emitted from the semiconductor laser element 202d. As a result, the light transmitted through the quarter-wave plate 211 is blocked by the analyzer 212.
　ソリッドイマージョンレンズ２１６とディスク２２１との間の距離が、光の波長の半分程度まで近づくと、ソリッドイマージョンレンズ２１６の底面に発生する近接場光とディスク２２１とが相互作用する。その結果、開口数ＮＡの高い成分の光がソリッドイマージョンレンズ２１６の底面で全反射されずにディスク２２１内に結合する。このため、ソリッドイマージョンレンズ２１６底面における全反射光の強度は、ソリッドイマージョンレンズ２１６とディスク２２１との間の距離が短くなるにつれて弱くなる。前述した構成により、受光素子２１５ｄは、ソリッドイマージョンレンズ２１６の底面にて全反射される光の強度を検出することによってギャップ信号ＧＴを生成し、アクチュエータ２１８に出力する。アクチュエータ２１８は、入力されたギャップ信号ＧＴに基づいてギャップ制御を行う。 When the distance between the solid immersion lens 216 and the disk 221 approaches about half of the wavelength of the light, the near-field light generated on the bottom surface of the solid immersion lens 216 and the disk 221 interact. As a result, light having a high numerical aperture NA is coupled into the disk 221 without being totally reflected by the bottom surface of the solid immersion lens 216. For this reason, the intensity of the totally reflected light on the bottom surface of the solid immersion lens 216 becomes weaker as the distance between the solid immersion lens 216 and the disk 221 becomes shorter. With the above-described configuration, the light receiving element 215 d generates a gap signal GT by detecting the intensity of light totally reflected on the bottom surface of the solid immersion lens 216, and outputs the gap signal GT to the actuator 218. The actuator 218 performs gap control based on the input gap signal GT.
　このように、本実施の形態３の光情報装置においては、アクチュエータ２１８は、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）をディスク２２１の表面に垂直な方向に移動させる。このとき、本実施の形態３の光情報装置においては、アクチュエータ２１８は、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）とディスク２２１との間の距離を検出する第２の検出素子（受光素子２１５ｄ）からの検出信号に応じて、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）とディスク２２１との間の距離が一定になるように、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）をディスク２２１の表面に垂直な方向に移動させる。 As described above, in the optical information device according to the third embodiment, the actuator 218 moves the plurality of resonance elements ( metal antennas 228b and 228c) in a direction perpendicular to the surface of the disk 221. At this time, in the optical information device according to the third embodiment, the actuator 218 has a second detection element (light receiving element 215d) that detects the distance between the plurality of resonance elements ( metal antennas 228b and 228c) and the disk 221. ), The plurality of resonance elements ( metal antennas 228b and 228c) are placed on the disk 221 so that the distance between the plurality of resonance elements ( metal antennas 228b and 228c) and the disk 221 is constant. Move in a direction perpendicular to the surface.
　続いて、本実施の形態３における光情報装置のトラッキング検出方法および情報の記録又は再生方法について説明する。 Subsequently, a tracking detection method and an information recording or reproducing method of the optical information device according to the third embodiment will be described.
　半導体レーザ素子２０２ａ、２０２ｂ及び２０２ｃから出射された光は、レンズ２０４によりコリメートされ、ハーフミラー２０９で反射される。ハーフミラー２０９で反射された光は、ダイクロイックミラー２１０を透過し、レンズ２０７とソリッドイマージョンレンズ２１６とにより集光される。集光された光は、ソリッドイマージョンレンズ２１６の底面に形成された金属アンテナ２２８ａ、２２８ｂ及び２２８ｃに入射し、対応する金属アンテナ２２８ａ、２２８ｂ及び２２８ｃにプラズモン共鳴を励起する。励起されたプラズモン共鳴は、それぞれ対応する波長の散乱光を発生する。 The light emitted from the semiconductor laser elements 202a, 202b and 202c is collimated by the lens 204 and reflected by the half mirror 209. The light reflected by the half mirror 209 passes through the dichroic mirror 210 and is collected by the lens 207 and the solid immersion lens 216. The condensed light is incident on metal antennas 228a, 228b, and 228c formed on the bottom surface of the solid immersion lens 216, and excites plasmon resonance in the corresponding metal antennas 228a, 228b, and 228c. Each excited plasmon resonance generates scattered light having a corresponding wavelength.
　散乱光は、ソリッドイマージョンレンズ２１６とレンズ２０７とによってコリメートされ、ダイクロイックミラー２１０を透過する。ダイクロイックミラー２１０を透過した散乱光は、ハーフミラー２０９を透過した後、遮光板２１３を透過する。遮光板２１３の中央部分は遮光されており、反射された入射光を含む中央部分の光が遮光されることで、周辺部分を形成している散乱光のみが透過する。遮光板２１３を透過した散乱光は回折格子２１４により、波長ごとに異なる角度に回折され、レンズ２０６によって、それぞれに対応する受光素子２１５ａ、２１５ｂ及び２１５ｃに集光される。受光素子２１５ａ、２１５ｂ及び２１５ｃは、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃからの散乱光を検出する。 The scattered light is collimated by the solid immersion lens 216 and the lens 207 and passes through the dichroic mirror 210. The scattered light that has passed through the dichroic mirror 210 passes through the light shielding plate 213 after passing through the half mirror 209. The central portion of the light shielding plate 213 is shielded from light, and only the scattered light forming the peripheral portion is transmitted by shielding the central portion light including the reflected incident light. The scattered light transmitted through the light shielding plate 213 is diffracted by the diffraction grating 214 at different angles for each wavelength, and is condensed by the lens 206 onto the corresponding light receiving elements 215a, 215b, and 215c. The light receiving elements 215a, 215b, and 215c detect scattered light from the metal antennas 228a, 228b, and 228c.
　以上のように、本実施の形態３においては、光源は、それぞれ波長の異なる光を出射する複数の光源（半導体レーザ素子２０２ｂ及び２０２ｃ）を含む。また、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）は、複数の光源（半導体レーザ素子２０２ｂ及び２０２ｃ）のそれぞれから出射された光の周波数を共鳴周波数とする形状または材質で形成される。このとき、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）の各々の共鳴状態の変化を個別に検出して出力する第１の検出素子は、複数の受光素子２１５ｂ及び２１５ｃと、複数の共鳴素子からの周波数の異なる複数の光を分離して、複数の光のそれぞれを対応する複数の受光素子２１５ｂ及び２１５ｃに導く光学素子（回折格子２１４）とを含む。 As described above, in the third embodiment, the light source includes a plurality of light sources ( semiconductor laser elements 202b and 202c) that emit light having different wavelengths. The plurality of resonance elements ( metal antennas 228b and 228c) are formed in a shape or material having the resonance frequency as the frequency of light emitted from each of the plurality of light sources ( semiconductor laser elements 202b and 202c). At this time, the first detection element that individually detects and outputs the change in the resonance state of each of the plurality of resonance elements ( metal antennas 228b and 228c) includes the plurality of light receiving elements 215b and 215c and the plurality of resonance elements. And an optical element (diffraction grating 214) that separates the plurality of lights having different frequencies and guides each of the plurality of lights to the corresponding light receiving elements 215b and 215c.
　図２３（Ａ）は、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃのトラックからの距離に対する金属アンテナ２２８ａ、２２８ｂ及び２２８ｃからの散乱光強度の変化を示すグラフである。図２３（Ｂ）は、トラッキング用の受光素子２１５ｂ及び２１５ｃからの検出信号ｔｅ１及びｔｅ２の強度変化を示すグラフである。図２３（Ｃ）は、オペアンプ１１１により出力されるトラッキング信号ＴＥの強度変化を示すグラフである。 FIG. 23A is a graph showing changes in scattered light intensity from the metal antennas 228a, 228b and 228c with respect to the distance from the track of the metal antennas 228a, 228b and 228c. FIG. 23B is a graph showing intensity changes of the detection signals te1 and te2 from the tracking light receiving elements 215b and 215c. FIG. 23C is a graph showing a change in intensity of the tracking signal TE output from the operational amplifier 111.
　金属アンテナ２２８ａ、２２８ｂ及び２２８ｃからの散乱光強度は、図２３（Ａ）に示すように、トラック位置（グルーブ２０１からの距離がトラッキング周期Ｔｐと一致する位置）で最大となり、トラック（グルーブ２０１）からの距離がトラッキング周期Ｔｐの半分となる位置で最小となる。受光素子２１５ａの検出信号は再生信号として利用される。 As shown in FIG. 23A, the scattered light intensity from the metal antennas 228a, 228b, and 228c becomes maximum at the track position (position where the distance from the groove 201 coincides with the tracking period Tp), and the track (groove 201). Is the minimum at a position where the distance from is half the tracking period Tp. The detection signal of the light receiving element 215a is used as a reproduction signal.
　受光素子２１５ｂ及び２１５ｃの検出信号ｔｅ１及びｔｅ２は、図２３（Ｂ）のように変化し、トラッキング信号演算回路として機能するオペアンプ１１１に入力される。オペアンプ１１１は、トラックからの距離に対して検出信号ｔｅ１と検出信号ｔｅ２との差をトラッキング信号ＴＥとして図２３（Ｃ）に示すように出力する。このように、トラッキング信号演算回路であるオペアンプ１１１は、複数の共鳴素子（金属アンテナ２２８ｂ及び２２８ｃ）の各々の共鳴状態の変化に基づいてトラッキング信号ＴＥを演算する。 The detection signals te1 and te2 of the light receiving elements 215b and 215c change as shown in FIG. 23B and are input to the operational amplifier 111 that functions as a tracking signal arithmetic circuit. The operational amplifier 111 outputs the difference between the detection signal te1 and the detection signal te2 with respect to the distance from the track as a tracking signal TE as shown in FIG. As described above, the operational amplifier 111 serving as the tracking signal calculation circuit calculates the tracking signal TE based on the change in the resonance state of each of the plurality of resonance elements ( metal antennas 228b and 228c).
　本実施の形態３では、トラッキング用の金属アンテナ２２８ｂ及び２２８ｃは、記録又は再生用の金属アンテナ２２８ａに対してそれぞれトラックに垂直な方向に、トラッキング周期Ｔｐの４分の１だけ離して設置している。そのため、検出信号ｔｅ１と検出信号ｔｅ２との差を最大にすることができ、高精度なトラッキング信号ＴＥを得ることができる。 In the third embodiment, the tracking metal antennas 228b and 228c are set apart from the recording or reproduction metal antenna 228a by a quarter of the tracking period Tp in the direction perpendicular to the track. Yes. Therefore, the difference between the detection signal te1 and the detection signal te2 can be maximized, and a highly accurate tracking signal TE can be obtained.
　このように、本実施の形態３では、波長の違いを利用して金属アンテナ２２８ａ、２２８ｂ及び２２８ｃの個々の共鳴状態が検出される。このため、光源、第１の検出素子、導波路及び複数の共鳴素子を微小領域に集積化する必要がなく、光情報装置の作製が容易である。 As described above, in the third embodiment, the individual resonance states of the metal antennas 228a, 228b, and 228c are detected using the difference in wavelength. For this reason, it is not necessary to integrate the light source, the first detection element, the waveguide, and the plurality of resonance elements in a minute region, and the production of the optical information device is easy.
　また、本実施の形態３では、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃは、ディスク２２１の表面に対して平行になるように配置し、ディスク２２１の表面に平行な偏光方向を持つ入射光でプラズモン共鳴を励起する。このため、金属アンテナ２２８ａ、２２８ｂ及び２２８ｃをディスク２２１の表面に対して垂直に保持する必要がなく、作製が容易である。 In the third embodiment, the metal antennas 228a, 228b, and 228c are arranged so as to be parallel to the surface of the disk 221, and plasmon resonance is performed by incident light having a polarization direction parallel to the surface of the disk 221. Excited. For this reason, it is not necessary to hold the metal antennas 228a, 228b, and 228c perpendicular to the surface of the disk 221, and the manufacturing is easy.
　また、本実施の形態３では、ディスク２２１にグルーブ２０１が形成されている。このため、微粒子を配列した情報記録媒体と比較して大きなトラッキング信号が得られる。 In the third embodiment, the groove 201 is formed on the disk 221. Therefore, a large tracking signal can be obtained as compared with an information recording medium in which fine particles are arranged.
　さらに、本実施の形態３では、反射光の強度の変化を検出することによりギャップ制御が行われる。このため、従来の光ピックアップに用いられていた技術からの応用が容易であると同時に、リムーバブルな情報記録媒体への応用も可能である。 Furthermore, in the third embodiment, gap control is performed by detecting a change in the intensity of reflected light. For this reason, the application from the technique used in the conventional optical pickup is easy, and at the same time, the application to a removable information recording medium is also possible.
　なお、本実施の形態３では、情報記録媒体としてグルーブを有するディスクを用いているが、グルーブを形成する代わりに実施の形態１及び２で用いた、列状に配置された微粒子を用いても良い。 In the third embodiment, a disk having a groove is used as the information recording medium. However, instead of forming the groove, the fine particles arranged in rows used in the first and second embodiments may be used. good.
　また、本実施の形態３では、金属アンテナの形状は三角平板形状であるが、金属アンテナの形状は上記の例に特に限定されず、例えば三角平板形状以外にも図２４～図２６に示すような形状であってもよい。金属アンテナの形状は、トラック上でプラズモン共鳴し、トラックからの距離に応じて効率よくプラズモン共鳴状態が変化するものであれば、特に限定されるものではない。 In the third embodiment, the shape of the metal antenna is a triangular plate shape. However, the shape of the metal antenna is not particularly limited to the above example, and for example, as shown in FIGS. It may be a simple shape. The shape of the metal antenna is not particularly limited as long as plasmon resonance occurs on the track and the plasmon resonance state efficiently changes according to the distance from the track.
　図２４は、本発明の実施の形態３において、扇板形状である金属アンテナを示す図であり、図２５は、本発明の実施の形態３において、ボウタイ形状である金属アンテナを示す図であり、図２６は、本発明の実施の形態３において、ナノビーク形状である金属アンテナを示す図である。 FIG. 24 is a diagram showing a fan-shaped metal antenna in Embodiment 3 of the present invention, and FIG. 25 is a diagram showing a bow-tie metal antenna in Embodiment 3 of the present invention. FIG. 26 is a diagram showing a metal antenna having a nanobeak shape in the third embodiment of the present invention.
　図２４のように、金属アンテナ１１７の形状が扇板形状である場合、三角平板形状に比べて底辺部分での寄生光の影響が緩和される。また、図２５のように、金属アンテナ１１７の形状がボウタイ形状である場合、金属アンテナの頂点が向かい合っている部分において、三角平板形状と比べて効率よく近接場光を発生させることができる。また、図２６のように、金属アンテナ１１７の形状がナノビーク形状である場合、三次元的に近接場光を集光させることができ、効率よく近接場光を発生させることができる。 As shown in FIG. 24, when the shape of the metal antenna 117 is a fan shape, the influence of the parasitic light at the bottom side portion is reduced as compared with the triangular plate shape. In addition, as shown in FIG. 25, when the shape of the metal antenna 117 is a bow tie shape, near-field light can be generated more efficiently in the portion where the apexes of the metal antenna face each other than the triangular plate shape. Further, as shown in FIG. 26, when the shape of the metal antenna 117 is a nano-beek shape, the near-field light can be condensed three-dimensionally and the near-field light can be generated efficiently.
　また、本実施の形態３では、記録又は再生用の金属アンテナ２２８ａは、２つのトラッキング用の金属アンテナ２２８ｂ及び２２８ｃのトラックの長手方向の間に配置されているが、本発明は特にこれに限定されず、図２７～図２９に示すような配置であってもよい。 In the third embodiment, the recording or reproducing metal antenna 228a is disposed between the two tracking metal antennas 228b and 228c in the longitudinal direction of the track. However, the present invention is particularly limited to this. Instead, the arrangement shown in FIGS. 27 to 29 may be used.
　図２７は、本発明の実施の形態３においてトラッキング用の金属アンテナを近づけて配置する例を示す図であり、図２８は、本発明の実施の形態３において、トラッキング用の金属アンテナの向きを異ならせて配置する例を示す図であり、図２９は、本発明の実施の形態３において、記録又は再生用の金属アンテナとトラッキング用の金属アンテナとの向きが互いに直交するように配置する例を示す図である。 FIG. 27 is a diagram showing an example in which the tracking metal antenna is arranged close to the third embodiment of the present invention, and FIG. 28 shows the direction of the tracking metal antenna in the third embodiment of the present invention. FIG. 29 is a diagram showing an example of disposing differently, and FIG. 29 is an example of disposing the recording or reproducing metal antenna and the tracking metal antenna so that the directions thereof are orthogonal to each other in the third embodiment of the present invention. FIG.
　例えば、図２７に示すように、記録又は再生用の金属アンテナ２２８ａは独立して配置され、トラッキング用の金属アンテナ２２８ｂ及び２２８ｃが互いに近づくように配置してもよい。図２７のような構成では、トラッキング用の金属アンテナ２２８ｂ及び２２８ｃの相対距離が近づくため、トラッキング精度が向上する。 For example, as shown in FIG. 27, the recording or reproducing metal antenna 228a may be arranged independently, and the tracking metal antennas 228b and 228c may be arranged so as to approach each other. In the configuration as shown in FIG. 27, since the relative distance between the tracking metal antennas 228b and 228c is closer, the tracking accuracy is improved.
　また、本実施の形態３では、トラッキング用の金属アンテナ２２８ｂ及び２２８ｃは全て同じ向きに配置されているが、図２８に示すように、トラッキング用の金属アンテナ２２８ｂ及び２２８ｃの向きをトラックの長手方向に対して互いに対向させて、トラッキング用の金属アンテナ２２８ｂ及び２２８ｃのトラックの長手方向の互いの頂点の位置が近づくように配置してもよい。図２８のような構成では、トラッキング用の金属アンテナ２２８ｂ及び２２８ｃのトラックの長手方向の検出位置が一致しているため、トラッキング精度が向上する。 In the third embodiment, the tracking metal antennas 228b and 228c are all arranged in the same direction. However, as shown in FIG. 28, the tracking metal antennas 228b and 228c are oriented in the longitudinal direction of the track. The tracking metal antennas 228b and 228c may be arranged so that the positions of the vertices in the longitudinal direction of the tracks approach each other. In the configuration shown in FIG. 28, the tracking metal antennas 228b and 228c have the same detection position in the longitudinal direction of the track, so that tracking accuracy is improved.
　また、本実施の形態３では、金属アンテナ２２８ｂ及び２２８ｃの共鳴状態を散乱光の波長の違いを用いて分離しているが、図２９に示すように、記録又は再生用の金属アンテナ２２８ａとトラッキング用の金属アンテナ２２８ｂ及び２２８ｃとの向きが互いに直交するように配置してもよい。すなわち、トラッキング用の金属アンテナ２２８ｂ及び２２８ｃが、トラックに垂直な方向に互いに対向するように配置され、記録又は再生用の金属アンテナ２２８ａの散乱光とトラッキング用の金属アンテナ２２８ｂ及び２２８ｃの散乱光とを偏光方向の違いを用いて分離しても良い。図２９のような構成を用いれば、波長の異なる光を出射する光源の数を減らすことができる。 In the third embodiment, the resonance states of the metal antennas 228b and 228c are separated using the difference in the wavelength of the scattered light. However, as shown in FIG. 29, the recording or reproducing metal antenna 228a and the tracking are separated. The metal antennas 228b and 228c may be arranged so that their directions are orthogonal to each other. That is, the tracking metal antennas 228b and 228c are arranged so as to face each other in the direction perpendicular to the track, and the scattered light of the recording or reproducing metal antenna 228a and the scattered light of the tracking metal antennas 228b and 228c May be separated using a difference in polarization direction. If the configuration as shown in FIG. 29 is used, the number of light sources that emit light having different wavelengths can be reduced.
　以上、実施の形態１、実施の形態２及び実施の形態３において説明した光情報装置の主な構成を下記に示す。 The main configuration of the optical information apparatus described in the first embodiment, the second embodiment, and the third embodiment is described below.
　実施の形態１、実施の形態２及び実施の形態３において説明した光情報装置は、トラックを有する情報記録媒体に情報を記録又は再生する光情報装置であって、光源と、光源からの光が入射し、情報記録媒体と相互作用し、トラックからの距離に応じて共鳴状態が変化する複数の共鳴素子と、複数の共鳴素子の位置をトラックに垂直な方向にずらして配置し、かつ複数の共鳴素子間の距離を一定に固定して保持する保持素子と、複数の共鳴素子の各々の共鳴状態の変化を個別に検出する第１の検出素子と、第１の検出素子によって検出された共鳴状態の変化に基づいてトラッキング信号を演算するトラッキング信号演算回路と、トラッキング信号演算回路によって演算されたトラッキング信号に応じて保持素子をトラックに垂直な方向に移動させる第１の移動素子と、を備えている。 The optical information device described in the first embodiment, the second embodiment, and the third embodiment is an optical information device that records or reproduces information on an information recording medium having a track, and includes a light source and light from the light source. A plurality of resonant elements that are incident, interact with the information recording medium, and whose resonance states change according to the distance from the track; and positions of the plurality of resonant elements are shifted in a direction perpendicular to the track; A holding element that holds the distance between the resonance elements fixed at a fixed level, a first detection element that individually detects a change in the resonance state of each of the plurality of resonance elements, and a resonance detected by the first detection element A tracking signal calculation circuit that calculates a tracking signal based on a change in state, and a holding element is moved in a direction perpendicular to the track according to the tracking signal calculated by the tracking signal calculation circuit. And a, a first moving element to be.
　以上のように、トラックからの距離に応じて共鳴状態の変化する複数の共鳴素子の位置がトラックに垂直な方向にずらして配置され、かつ複数の共鳴素子間の距離が一定に固定されて保持される。これにより、相互作用により複数の共鳴素子とトラック上の情報記録位置との相対的な位置が変化することがない。このため、トラック位置からの変位にのみ依存した安定かつ高精度なトラッキング信号を得ることができる。さらに、共鳴状態は共鳴素子周辺の光学定数の変化に敏感に反応する。このため、トラック上の情報記録状態が表面形状変化を伴わない情報記録状態であっても安定かつ高精度にトラッキングすることができる。 As described above, the positions of the plurality of resonance elements whose resonance states change according to the distance from the track are shifted in the direction perpendicular to the track, and the distances between the plurality of resonance elements are fixedly held. Is done. As a result, the relative position between the plurality of resonance elements and the information recording position on the track does not change due to the interaction. For this reason, a stable and highly accurate tracking signal depending only on the displacement from the track position can be obtained. Furthermore, the resonance state is sensitive to changes in the optical constants around the resonance element. For this reason, even if the information recording state on the track is an information recording state not accompanied by a change in surface shape, tracking can be performed stably and with high accuracy.
　また、光情報装置は、複数の共鳴素子の共鳴状態の変化が複数の受光素子によって個別に検出され、検出信号の差がトラッキング信号として出力される。これにより、検出信号が共鳴素子周辺の光学定数の変化に敏感に反応し、微小なトラックからの位置ずれに対して変調度の高いトラッキング信号が得られる。このため、安定かつ高精度なトラッキング信号を得ることができる。 Further, in the optical information device, the change in the resonance state of the plurality of resonance elements is individually detected by the plurality of light receiving elements, and the difference between the detection signals is output as a tracking signal. As a result, the detection signal reacts sensitively to changes in the optical constants around the resonant element, and a tracking signal having a high degree of modulation with respect to a positional deviation from a minute track can be obtained. For this reason, a stable and highly accurate tracking signal can be obtained.
　（実施の形態４）
　次に、本発明の実施の形態４における光情報装置について説明する。 (Embodiment 4)
Next, an optical information device according to Embodiment 4 of the present invention will be described.
　図３０は、本発明の実施の形態４における光情報装置の構成を示す概略図であり、図３１は、本発明の実施の形態４における光情報装置の構成を示す上面図である。図３２は、図３０に示すスライダの構成を示す斜視図であり、図３３は、図３０に示すスライダの構成を示す側面図であり、図３４は、図３０に示すスライダの構成を示す上面図である。図３０～図３４において、図１～図４、図９～図１２と同じ構成要素については同じ符号を用い、説明を省略する。 FIG. 30 is a schematic diagram showing the configuration of the optical information apparatus in the fourth embodiment of the present invention, and FIG. 31 is a top view showing the configuration of the optical information apparatus in the fourth embodiment of the present invention. 32 is a perspective view showing the configuration of the slider shown in FIG. 30, FIG. 33 is a side view showing the configuration of the slider shown in FIG. 30, and FIG. 34 is a top view showing the configuration of the slider shown in FIG. FIG. 30 to 34, the same components as those in FIGS. 1 to 4 and FIGS. 9 to 12 are denoted by the same reference numerals, and description thereof is omitted.
　図３０～図３４において、光情報装置は、半導体レーザ素子１０７ａ，１０７ｂ，１０７ｃ、金属アンテナ１２８ａ，１２８ｂ，１２８ｃ、導波路１２９ａ，１２９ｂ，１２９ｃ、受光素子１２０ａ，１２０ｂ，１２０ｃ、モータ１０３、エアスライダ１３２、スライダ１４１、サスペンション１４２、モータ１４３、ピエゾ素子１４４ａ，１４４ｂ、ヨーイング信号演算回路１５１及びトラッキング信号演算回路１６１を備える。 30 to 34, the optical information device includes semiconductor laser elements 107a, 107b, 107c, metal antennas 128a, 128b, 128c, waveguides 129a, 129b, 129c, light receiving elements 120a, 120b, 120c, a motor 103, an air slider. 132, a slider 141, a suspension 142, a motor 143, piezo elements 144a and 144b, a yawing signal calculation circuit 151, and a tracking signal calculation circuit 161.
　図３０及び図３１において、トラック状に並んだ微粒子１０２を有するディスク１０１がモータ１０３に固定されて保持されている。 30 and 31, a disk 101 having fine particles 102 arranged in a track shape is fixed and held by a motor 103.
　また、保持素子としてのスライダ１４１は、共鳴素子としての金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの位置をトラック１１２に垂直な方向にずらして配置し、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃ間の距離を一定に固定して保持する。 The slider 141 as a holding element is arranged by shifting the positions of the metal antennas 128a, 128b and 128c as resonance elements in the direction perpendicular to the track 112, and the distance between the metal antennas 128a, 128b and 128c is fixed. And hold.
　共鳴素子である金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、半導体レーザ素子１０７ｂ及び１０７ｃからの光が入射し、ディスク１０１と相互作用し、トラック１１２からの距離に応じて、共鳴状態が変化する。実施の形態４における金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、実施の形態１における金属アンテナ１０８ａ、１０８ｂ及び１０８ｃと同様に、例えば金、銀、銅、チタン、アルミ又はクロムなどの材料で構成される。また、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの形状は、三角平板形状である。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、三角形の１つの頂点が微粒子１０２の表面に最も近接するように配置され、プラズモン共鳴が励起されることにより三角形の頂点近傍に強い近接場光が発生する。また、実施の形態１における金属アンテナ１０８ａ、１０８ｂ及び１０８ｃと同様に、実施の形態４における金属アンテナ１２８ａ、１２８ｂ及び１２８ｃと微粒子１０２の表面との距離は数十ｎｍ以下であることが好ましく、数ｎｍであることがより好ましい。 Metal antennas 128a, 128b, and 128c, which are resonance elements, receive light from semiconductor laser elements 107b and 107c, interact with disk 101, and the resonance state changes according to the distance from track 112. Similarly to the metal antennas 108a, 108b, and 108c in the first embodiment, the metal antennas 128a, 128b, and 128c in the fourth embodiment are made of a material such as gold, silver, copper, titanium, aluminum, or chromium. The metal antennas 128a, 128b, and 128c are triangular flat plate shapes. The metal antennas 128a, 128b, and 128c are arranged so that one vertex of the triangle is closest to the surface of the fine particle 102, and strong near-field light is generated near the vertex of the triangle when plasmon resonance is excited. Similarly to the metal antennas 108a, 108b, and 108c in the first embodiment, the distance between the metal antennas 128a, 128b, and 128c in the fourth embodiment and the surface of the fine particles 102 is preferably several tens of nm or less. More preferably, it is nm.
　なお、図３２～図３４の例では、金属アンテナ１２８ａと金属アンテナ１２８ｂとの間の距離Ｐ１は、金属アンテナ１２８ａと金属アンテナ１２８ｃとの間の距離Ｐ２よりも大きくなっている。 In the example of FIGS. 32 to 34, the distance P1 between the metal antenna 128a and the metal antenna 128b is larger than the distance P2 between the metal antenna 128a and the metal antenna 128c.
　実施の形態２で述べたように、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは微粒子１０２と相互作用し、一体となってプラズモン共鳴する。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃと微粒子１０２との共鳴状態は、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃ及び微粒子１０２の設計によって変化する。このため、設計次第で、プラズモン共鳴により金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度が増加する場合もあれば、プラズモン共鳴により金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度が減少する場合もある。本実施の形態４では、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度が微粒子１０２との共鳴により減少する場合を一例として示している。 As described in the second embodiment, the metal antennas 128a, 128b, and 128c interact with the microparticles 102 and plasmon resonate together. The resonance state between the metal antennas 128a, 128b, and 128c and the fine particles 102 varies depending on the design of the metal antennas 128a, 128b, and 128c and the fine particles 102. For this reason, depending on the design, the reflected light intensity from the metal antennas 128a, 128b, and 128c may increase due to plasmon resonance, or the reflected light intensity from the metal antennas 128a, 128b, and 128c may decrease due to plasmon resonance. is there. In the fourth embodiment, the case where the reflected light intensity from the metal antennas 128a, 128b, and 128c decreases due to resonance with the fine particles 102 is shown as an example.
　プラズモン共鳴の共鳴状態は、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃと微粒子１０２との距離に敏感に反応する。このため、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度は、実施の形態２の図１３（Ａ）に示すように、トラック位置（トラック１１２からの距離がトラッキング周期Ｔｐと一致する位置）で最小となり、トラック１１２からの距離がトラッキング周期Ｔｐの半分となる位置で最大となる。 The resonance state of plasmon resonance reacts sensitively to the distance between the metal antennas 128a, 128b and 128c and the fine particles 102. Therefore, the reflected light intensity from the metal antennas 128a, 128b, and 128c is the track position (position where the distance from the track 112 coincides with the tracking period Tp) as shown in FIG. 13A of the second embodiment. It becomes the minimum and becomes the maximum at the position where the distance from the track 112 becomes half of the tracking period Tp.
　エアスライダ１３２は、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃをディスク１０１の表面に垂直な方向に移動させる。サスペンション１４２は、ばね素子で構成される。スライダ１４１とエアスライダ１３２とは、サスペンション１４２によってディスク１０１に対向して保持されている。ハードディスクドライブに採用されるフライングヘッドと同様の技術を用いてスライダ１４１とディスク１０１との距離が一定になるように保たれている。 The air slider 132 moves the metal antennas 128a, 128b, and 128c in a direction perpendicular to the surface of the disk 101. The suspension 142 is composed of a spring element. The slider 141 and the air slider 132 are held facing the disk 101 by a suspension 142. The distance between the slider 141 and the disk 101 is kept constant by using a technique similar to that of a flying head employed in a hard disk drive.
　以上のように、本実施の形態４の光情報装置においては、複数の共鳴素子を情報記録媒体の表面に垂直な方向に移動させる第２の移動素子は、サスペンション１２５（ばね素子）を含んでいる。このとき、サスペンション１２５は、スライダ１０４及びエアスライダ１３２とディスク１０１との間を流れる気流の力により、ディスク１０１とスライダ１０４及びエアスライダ１３２との間の距離を一定に保持する。 As described above, in the optical information device according to the fourth embodiment, the second moving element that moves the plurality of resonant elements in the direction perpendicular to the surface of the information recording medium includes the suspension 125 (spring element). Yes. At this time, the suspension 125 keeps the distance between the disk 101, the slider 104, and the air slider 132 constant by the force of the airflow flowing between the slider 104 and the air slider 132 and the disk 101.
　サスペンション１４２は、モータ１４３によって回転される。これにより、第１の移動素子であるモータ１４３は、トラッキング信号に応じて保持素子（スライダ１４１）をトラック１１２に垂直な方向に移動させる。ディスク１０１が回転されることにより、スライダ１４１は、ディスク１０１上を走査する。 The suspension 142 is rotated by a motor 143. As a result, the motor 143 as the first moving element moves the holding element (slider 141) in a direction perpendicular to the track 112 in accordance with the tracking signal. As the disk 101 is rotated, the slider 141 scans the disk 101.
　ヨーイング信号演算回路１５１は、受光素子１２０ｂ及び１２０ｃによって検出された共鳴状態の変化に基づいて、ディスク１０１の表面に平行な面内におけるスライダ１４１の傾きを表すヨーイング信号を演算する。ヨーイング信号演算回路１５１は、金属アンテナ１２８ｂ及び１２８ｃの共鳴状態の変化を表す検出信号ｔｅ１及びｔｅ２に基づいてヨーイング信号を生成する。 The yawing signal calculation circuit 151 calculates a yawing signal that represents the inclination of the slider 141 in a plane parallel to the surface of the disk 101 based on the change in the resonance state detected by the light receiving elements 120b and 120c. The yawing signal calculation circuit 151 generates a yawing signal based on the detection signals te1 and te2 representing changes in the resonance state of the metal antennas 128b and 128c.
　ピエゾ素子１４４ａ及び１４４ｂは、サスペンション１４２に組み込まれている。ピエゾ素子１４４ａ及び１４４ｂは、互いに逆位相に伸縮してスライダ１４１をディスク１０１の表面に平行な面内で回転させる。回転素子であるピエゾ素子１４４ａ及び１４４ｂは、ヨーイング信号に応じてスライダ１４１をディスク１０１の表面に平行な面内で回転させ、金属アンテナ１２８ｂ及び１２８ｃのトラックに垂直な方向の相対距離を一定に保つ。 The piezo elements 144a and 144b are incorporated in the suspension 142. The piezo elements 144 a and 144 b expand and contract in opposite phases to rotate the slider 141 in a plane parallel to the surface of the disk 101. Piezo elements 144a and 144b, which are rotating elements, rotate the slider 141 in a plane parallel to the surface of the disk 101 according to the yawing signal, and keep the relative distance in the direction perpendicular to the tracks of the metal antennas 128b and 128c constant. .
　すなわち、ピエゾ素子１４４ａ及び１４４ｂは、金属アンテナ１２８ｂからトラックの中心を通る線へ下ろした垂線の長さと、金属アンテナ１２８ｃからトラックの中心を通る線へ下ろした垂線の長さとの和が一定となるように、スライダ１４１をディスク１０１の表面に平行な面内で回転させる。 That is, in the piezo elements 144a and 144b, the sum of the length of the perpendicular line extending from the metal antenna 128b to the line passing through the center of the track and the length of the perpendicular line extending from the metal antenna 128c to the line passing through the center of the track is constant. As described above, the slider 141 is rotated in a plane parallel to the surface of the disk 101.
　トラッキング信号演算回路１６１は、複数の検出信号に基づいて、金属アンテナ１２８ｂからトラックのトラックからの位置ずれを補正するための補正値を演算し、演算した補正値に基づいて補正した複数の検出信号の差をトラッキング信号として演算する。トラッキング信号演算回路１６１は、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの共鳴状態の変化を表す検出信号ｔｅ０、ｔｅ１及びｔｅ２に基づいてトラッキング信号を生成する。モータ１４３は、トラッキング信号に応じてスライダ１４１をトラック１１２に垂直な方向に移動させる。 The tracking signal calculation circuit 161 calculates a correction value for correcting the positional deviation of the track from the track from the metal antenna 128b based on the plurality of detection signals, and the plurality of detection signals corrected based on the calculated correction value. Is calculated as a tracking signal. The tracking signal calculation circuit 161 generates a tracking signal based on the detection signals te0, te1, and te2 representing changes in the resonance state of the metal antennas 128a, 128b, and 128c. The motor 143 moves the slider 141 in a direction perpendicular to the track 112 in accordance with the tracking signal.
　図３２～図３４において、スライダ１４１は、トラックの長手方向の端面にトラック１１２に垂直な方向に階段状の段差を有する。本実施の形態４では、階段状の端面は、トラックの長手方向に位置の異なる３つの面を有する。 32 to 34, the slider 141 has a stepped step in the direction perpendicular to the track 112 on the end face in the longitudinal direction of the track. In the fourth embodiment, the step-like end face has three faces whose positions are different in the longitudinal direction of the track.
　導波路１２９ａ、１２９ｂ及び１２９ｃは、半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃからの光を金属アンテナ１２８ａ、１２８ｂ及び１２８ｃに個別に導く。また、導波路１２９ａ、１２９ｂ及び１２９ｃは、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光を受光素子１２０ａ、１２０ｂ及び１２０ｃに個別に導く。受光素子１２０ａ、１２０ｂ及び１２０ｃは、半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃの近傍にそれぞれ配置されている。 The waveguides 129a, 129b and 129c individually guide light from the semiconductor laser elements 107a, 107b and 107c to the metal antennas 128a, 128b and 128c. The waveguides 129a, 129b and 129c individually guide the reflected light from the metal antennas 128a, 128b and 128c to the light receiving elements 120a, 120b and 120c. The light receiving elements 120a, 120b and 120c are arranged in the vicinity of the semiconductor laser elements 107a, 107b and 107c, respectively.
　また、受光素子１２０ａ、１２０ｂ及び１２０ｃは、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの各々の共鳴状態の変化を個別に検出する。受光素子１２０ａ、１２０ｂ及び１２０ｃは、複数の導波路１２９ａ、１２９ｂ及び１２９ｃにそれぞれ１つずつ取り付けられており、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光をそれぞれ個別に検出する。 The light receiving elements 120a, 120b, and 120c individually detect changes in the resonance states of the metal antennas 128a, 128b, and 128c. Each of the light receiving elements 120a, 120b, and 120c is attached to each of the plurality of waveguides 129a, 129b, and 129c, and individually detects the reflected light from the metal antennas 128a, 128b, and 128c.
　以上のように、本実施の形態４の光情報装置においては、複数の共鳴素子の各々の共鳴状態の変化を個別に検出して出力する第１の検出素子は、複数の受光素子１２０ａ、１２０ｂ及び１２０ｃを含み、光情報装置は、複数の共鳴素子からの光を複数の受光素子に導く複数の導波路１２９ａ、１２９ｂ及び１２９ｃを備える。 As described above, in the optical information device according to the fourth embodiment, the first detection elements that individually detect and output changes in the resonance states of the plurality of resonance elements are the plurality of light receiving elements 120a and 120b. The optical information device includes a plurality of waveguides 129a, 129b, and 129c that guide light from the plurality of resonance elements to the plurality of light receiving elements.
　スライダ１４１の階段状の端面には、それぞれ１つずつ合計３つの金属アンテナ１２８ａ、１２８ｂ及び１２８ｃが固定されている。複数の導波路１２９ａ、１２９ｂ及び１２９ｃにより導かれた半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃからの光によりプラズモン共鳴が励起される。 A total of three metal antennas 128a, 128b, and 128c are fixed to the stepped end face of the slider 141, one each. Plasmon resonance is excited by light from the semiconductor laser elements 107a, 107b, and 107c guided by the plurality of waveguides 129a, 129b, and 129c.
　なお、２つの金属粒子間の相互作用は、金属粒子間の距離が数十ｎｍ以下であるときに顕著に現れる（Ｃｏｎｆｉｎｅｄ　ｐｌａｓｍｏｎｓ　ｉｎ　ｎａｎｏｆａｂｒｉｃａｔｅｄ　ｓｉｎｇｌｅ　ｓｉｌｖｅｒ　ｐａｒｔｉｃｌｅ　ｐａｉｒｓ：　ｅｘｐｅｒｉｍｅｎｔａｌ　ｏｂｓｅｒｖａｔｉｏｎｓ　ｏｆ　ｓｔｒｏｎｇ　ｉｎｔｅｒｐａｒｔｉｃｌｅ　ｉｎｔｅｒａｃｔｉｏｎｓ，Ｌ．Ｇｕｎｎａｒｓｓｏｎ　ｅｔ．ａｌ．，Ｊ．Ｐｈｙｓ．Ｃｈｅｍ．Ｂ，２００５，１０９，１０７９－１０８７）。そのため、金属アンテナ１２８ａと金属アンテナ１２８ｂとの間のトラックの長手方向の段差及び金属アンテナ１２８ａと金属アンテナ１２８ｃとの間のトラックの長手方向の段差の大きさＬは、数十ｎｍ以上とする。これにより、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃ間での相互作用を抑制することができ、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの形状の自由度が高くなる。 In addition, the interaction between two metal particles appears prominently when the distance between the metal particles is several tens of nanometers or less (Confined plasmas in nanofabricated partialspars: experiential severinstrands. Al., J. Phys. Chem. B, 2005, 109, 1079-1087). Therefore, the length L in the longitudinal direction of the track between the metal antenna 128a and the metal antenna 128b and the length L in the longitudinal direction of the track between the metal antenna 128a and the metal antenna 128c are set to several tens of nm or more. Thereby, the interaction between the metal antennas 128a, 128b and 128c can be suppressed, and the degree of freedom of the shape of the metal antennas 128a, 128b and 128c is increased.
　一方、トラッキング用の金属アンテナ１２８ｂ及び１２８ｃは、記録又は再生用の金属アンテナ１２８ａを中心にして、トラックに垂直な方向に配置される。金属アンテナ１２８ｂ及び１２８ｃは、金属アンテナ１２８ａからトラック１１２に垂直な方向にそれぞれ任意の距離Ｐ１及びＰ２だけ離れた位置に配置される。 On the other hand, the tracking metal antennas 128b and 128c are arranged in a direction perpendicular to the track with the recording or reproduction metal antenna 128a as the center. The metal antennas 128b and 128c are arranged at positions separated from the metal antenna 128a by arbitrary distances P1 and P2 in a direction perpendicular to the track 112, respectively.
　図３５は、図３０に示すヨーイング信号演算回路１５１の構成を示す図である。ヨーイング信号演算回路１５１は、位相比較回路１５２、第１の制御回路１５３、第１のサンプリングホールド回路１５４ａ、第２のサンプリングホールド回路１５４ｂ、第１の加算回路１５５ａ、第２の加算回路１５５ｂ、差分回路１５６、第２の制御回路１５７及びスイッチ１５８を備える。 FIG. 35 is a diagram showing the configuration of the yawing signal calculation circuit 151 shown in FIG. The yawing signal operation circuit 151 includes a phase comparison circuit 152, a first control circuit 153, a first sampling hold circuit 154a, a second sampling hold circuit 154b, a first addition circuit 155a, a second addition circuit 155b, and a difference. A circuit 156, a second control circuit 157, and a switch 158 are provided.
　なお、図３５では、金属アンテナ１２８ａの先端位置１７１ａがトラックの中心上にある場合の金属アンテナ１２８ｂの先端位置１７１ｂ及び金属アンテナ１２８ｃの先端位置１７１ｃの位置ずれを示している。また、図３５では、金属アンテナ１２８ｂの先端位置１７１ｂ及び金属アンテナ１２８ｃの先端位置１７１ｃから検出信号ｔｅ１及びｔｅ２が出力されているように記載しているが、実際には、検出信号ｔｅ１及びｔｅ２は、受光素子１２０ｂ及び１２０ｃから出力される。 Note that FIG. 35 shows a positional shift between the tip position 171b of the metal antenna 128b and the tip position 171c of the metal antenna 128c when the tip position 171a of the metal antenna 128a is on the center of the track. In FIG. 35, the detection signals te1 and te2 are described as being output from the tip position 171b of the metal antenna 128b and the tip position 171c of the metal antenna 128c. Are output from the light receiving elements 120b and 120c.
　位相比較回路１５２は、検出信号ｔｅ１及びｔｅ２の位相を比較し、検出信号ｔｅ１及びｔｅ２の位相差を第１のヨーイング信号ＹＥ１として出力する。第１の制御回路１５３は、第１のヨーイング信号ＹＥ１がπラジアンとなるようにピエゾ素子１４４ａ及び１４４ｂを駆動する信号を出力する。 The phase comparison circuit 152 compares the phases of the detection signals te1 and te2, and outputs the phase difference between the detection signals te1 and te2 as the first yawing signal YE1. The first control circuit 153 outputs a signal for driving the piezo elements 144a and 144b so that the first yawing signal YE1 becomes π radians.
　第１のサンプリングホールド回路１５４ａは、ヨーイング信号ＹＥ１がπラジアンとなった際の検出信号ｔｅ１の値を初期値ｔｅ１０として記憶して出力する。また、第２のサンプリングホールド回路１５４ｂは、ヨーイング信号ＹＥ１がπラジアンとなった際の検出信号ｔｅ２の値を初期値ｔｅ２０として記憶して出力する。 The first sample and hold circuit 154a stores and outputs the value of the detection signal te1 when yawing signal YE1 becomes π radians as an initial value te1 0. The second sample and hold circuit 154b, and outputs the stored value of the detection signal te2 when yawing signal YE1 becomes π radians as an initial value te2 0.
　第１の加算回路１５５ａは、初期値ｔｅ１０と初期値ｔｅ２０との和を算出して出力する。第２の加算回路１５５ｂは、検出信号ｔｅ１と検出信号ｔｅ２との和を算出して出力する。差分回路１５６は、検出信号ｔｅ１と検出信号ｔｅ２との加算値（ｔｅ１＋ｔｅ２）から、初期値ｔｅ１０と初期値ｔｅ２０との加算値（ｔｅ１０＋ｔｅ２０）を減算し、ヨーイング信号ＹＥ２として出力する。 The first addition circuit 155a calculates and outputs the sum of the initial value te1 0 and the initial value te2 0 . The second addition circuit 155b calculates and outputs the sum of the detection signal te1 and the detection signal te2. The difference circuit 156 subtracts the addition value (te1 0 + te2 0 ) of the initial value te1 0 and the initial value te2 0 from the addition value (te1 + te2) of the detection signal te1 and the detection signal te2, and outputs the result as the yawing signal YE2. .
　第２の制御回路１５７は、金属アンテナ１２８ｂ及び１２８ｃの間のトラックに垂直な方向の距離がトラッキング周期Ｔｐの半分に保たれるように、ヨーイング信号ＹＥ２に応じてピエゾ素子１４４ａ及び１４４ｂを駆動する駆動信号を出力する。 The second control circuit 157 drives the piezo elements 144a and 144b according to the yawing signal YE2 so that the distance in the direction perpendicular to the track between the metal antennas 128b and 128c is maintained at half of the tracking period Tp. A drive signal is output.
　スイッチ１５８は、ピエゾ素子１４４ａ，１４４ｂとの接続先を、第１の制御回路１５３と、第２の制御回路１５７とのいずれかに切り替える。 The switch 158 switches the connection destination of the piezo elements 144a and 144b to either the first control circuit 153 or the second control circuit 157.
　次に、ヨーイング信号を用いた制御シーケンスを説明する。ヨーイング信号を用いた制御シーケンスは、ヨーイング信号ＹＥ１を用いて金属アンテナ１２８ａ及び１２８ｂの間のトラックに垂直な方向の距離がトラッキング周期Ｔｐの半分になるように、スライダ１４１の傾きを調節する第１のステップと、ヨーイング信号ＹＥ２を用いて金属アンテナ１２８ａ及び１２８ｂの間のトラックに垂直な方向の距離がトラッキング周期Ｔｐの半分になるように、スライダ１４１の傾きを保つ第２のステップとを含む。 Next, the control sequence using the yawing signal will be described. The control sequence using the yawing signal is a first control that uses the yawing signal YE1 to adjust the inclination of the slider 141 so that the distance between the metal antennas 128a and 128b in the direction perpendicular to the track is half the tracking period Tp. And a second step of maintaining the tilt of the slider 141 so that the distance in the direction perpendicular to the track between the metal antennas 128a and 128b becomes half the tracking period Tp using the yawing signal YE2.
　第１のステップにおいて、まず、モータ１４３は、スライダ１４１をトラックに垂直な方向に微少量走査させる。金属アンテナ１２８ｂ及び１２８ｃの共鳴強度に対応した検出信号ｔｅ１及びｔｅ２は、図１３（Ａ）に示すように、トラック１１２からの距離に対して周期的に変化する。検出信号ｔｅ１及びｔｅ２は、位相比較回路１５２に入力される。位相比較回路１５２は、検出信号ｔｅ１の位相と検出信号ｔｅ２の位相とを比較し、２つの検出信号の位相差をヨーイング信号ＹＥ１として出力する。 In the first step, first, the motor 143 scans the slider 141 in a small amount in the direction perpendicular to the track. The detection signals te1 and te2 corresponding to the resonance intensities of the metal antennas 128b and 128c periodically change with respect to the distance from the track 112, as shown in FIG. The detection signals te1 and te2 are input to the phase comparison circuit 152. The phase comparison circuit 152 compares the phase of the detection signal te1 with the phase of the detection signal te2, and outputs the phase difference between the two detection signals as the yawing signal YE1.
　第１の制御回路１５３は、位相比較回路１５２から出力されるヨーイング信号ＹＥ１がπラジアンとなるように、ピエゾ素子１４４ａ及び１４４ｂを駆動する駆動信号を出力する。このとき、スイッチ１５８は、第１の制御回路１５３と、ピエゾ素子１４４ａ及び１４４ｂとを接続する。２つの検出信号の位相差がπラジアンとなっているとき、金属アンテナ１２８ｂ及び１２８ｃのトラックに垂直な方向の距離は、トラッキング周期Ｔｐの半分となる。 The first control circuit 153 outputs a drive signal for driving the piezo elements 144a and 144b so that the yawing signal YE1 output from the phase comparison circuit 152 becomes π radians. At this time, the switch 158 connects the first control circuit 153 and the piezo elements 144a and 144b. When the phase difference between the two detection signals is π radians, the distance in the direction perpendicular to the tracks of the metal antennas 128b and 128c is half of the tracking period Tp.
　金属アンテナ１２８ｂ及び１２８ｃの間のトラックに垂直な方向の距離がトラッキング周期Ｔｐの半分になるように、スライダ１４１の傾きを調整した後、モータ１４３は、スライダ１４１のトラックに垂直な方向への走査を終了する。第１のサンプリングホールド回路１５４ａは、ヨーイング信号ＹＥ１がπラジアンとなった際の検出信号ｔｅ１の値をサンプリングし、初期値ｔｅ１０として記憶する。また、第２のサンプリングホールド回路１５４ｂは、ヨーイング信号ＹＥ１がπラジアンとなった際の検出信号ｔｅ２の値をサンプリングし、初期値ｔｅ２０として記憶する。 After adjusting the tilt of the slider 141 so that the distance in the direction perpendicular to the track between the metal antennas 128b and 128c is half of the tracking period Tp, the motor 143 scans in the direction perpendicular to the track of the slider 141. Exit. The first sample and hold circuit 154a samples the value of the detection signal te1 when yawing signal YE1 becomes π radians, is stored as an initial value te1 0. The second sample and hold circuit 154b samples the value of the detection signal te2 when yawing signal YE1 becomes π radians, is stored as an initial value te2 0.
　続いて、第２のステップにおいて、まず、第１のサンプリングホールド回路１５４ａは、検出信号ｔｅ１の初期値ｔｅ１０を出力し、第２のサンプリングホールド回路１５４ｂは、検出信号ｔｅ２の初期値ｔｅ２０を出力する。第１の加算回路１５５ａは、初期値ｔｅ１０と初期値ｔｅ２０とを加算する。第１の加算回路１５５ａは、基準値として常に２つの初期値ｔｅ１０及びｔｅ２０の和（ｔｅ１０＋ｔｅ２０）を出力する。 Subsequently, in a second step, firstly, the first sample and hold circuit 154a outputs an initial value te1 0 of the detection signal te1, the second sample and hold circuit 154b sets the initial value te2 0 of the detection signal te2 Output. The first addition circuit 155a adds the initial value te1 0 and the initial value te2 0 . The first addition circuit 155a always outputs the sum (te1 0 + te2 0 ) of two initial values te1 0 and te2 0 as a reference value.
　一方、第２の加算回路１５５ｂは、検出信号ｔｅ１と検出信号ｔｅ２とを加算する。第２の加算回路１５５ｂは、検出信号ｔｅ１及びｔｅ２の和（ｔｅ１＋ｔｅ２）を出力する。差分回路１５６は、検出信号ｔｅ１と検出信号ｔｅ２との加算値から、初期値ｔｅ１０と初期値ｔｅ２０との加算値を減算し、ヨーイング信号ＹＥ２（ＹＥ２＝（ｔｅ１＋ｔｅ２）－（ｔｅ１０＋ｔｅ２０））として出力する。ヨーイング信号ＹＥ２は、検出信号ｔｅ１及びｔｅ２の和の初期値からの変化量を示す。 On the other hand, the second addition circuit 155b adds the detection signal te1 and the detection signal te2. The second addition circuit 155b outputs the sum (te1 + te2) of the detection signals te1 and te2. The difference circuit 156 subtracts the addition value of the initial value te1 0 and the initial value te2 0 from the addition value of the detection signal te1 and the detection signal te2, and the yawing signal YE2 (YE2 = (te1 + te2) − (te1 0 + te2 0). )). The yawing signal YE2 indicates the amount of change from the initial value of the sum of the detection signals te1 and te2.
　第２の制御回路１５７は、金属アンテナ１２８ｂ及び１２８ｃの間のトラック１１２に垂直な方向の距離がトラッキング周期Ｔｐの半分に保たれるように、ヨーイング信号ＹＥ２に応じてピエゾ素子１４４ａ及び１４４ｂを駆動する駆動信号を出力する。このとき、スイッチ１５８は、第２の制御回路１５７と、ピエゾ素子１４４ａ及び１４４ｂとを接続する。 The second control circuit 157 drives the piezo elements 144a and 144b according to the yawing signal YE2 so that the distance in the direction perpendicular to the track 112 between the metal antennas 128b and 128c is maintained at half of the tracking period Tp. Drive signal to output. At this time, the switch 158 connects the second control circuit 157 and the piezo elements 144a and 144b.
　次に、ヨーイング信号ＹＥ２の生成原理について、金属アンテナ１２８ｂとトラック中心との間のトラックに垂直な方向の距離Ｐ１と、金属アンテナ１２８ｃとトラック中心との間のトラックに垂直な方向の距離Ｐ２とが、ともにトラッキング周期Ｔｐの１／４となる（Ｐ１＝Ｐ２＝Ｔｐ／４）場合について、図３６～図３９を用いて説明する。 Next, regarding the generation principle of the yawing signal YE2, the distance P1 in the direction perpendicular to the track between the metal antenna 128b and the track center, and the distance P2 in the direction perpendicular to the track between the metal antenna 128c and the track center, However, the case where both are 1/4 of the tracking period Tp (P1 = P2 = Tp / 4) will be described with reference to FIGS.
　図３６は、Ｐ１＝Ｐ２＝Ｔｐ／４の場合におけるトラック角度変化について説明するための概念図である。図３６に示すように、ディスク１０１の偏心又はモータ１４３とサスペンション１４２とを用いたトラックに垂直な方向への移動によりトラック角度が変化すると、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃのトラックに垂直な方向の距離が変化する。すなわち、金属アンテナ１２８ａの先端位置１７１ａを中心にしてトラックが反時計回りに傾くことにより、金属アンテナ１２８ｂの先端位置１７１ｂとトラック中心との間の距離Ｐ１は、大きくなり、金属アンテナ１２８ｃの先端位置１７１ｃとトラック中心との間の距離Ｐ２は、大きくなる。 FIG. 36 is a conceptual diagram for explaining the track angle change in the case of P1 = P2 = Tp / 4. As shown in FIG. 36, when the track angle changes due to the eccentricity of the disk 101 or the movement in the direction perpendicular to the track using the motor 143 and the suspension 142, the direction perpendicular to the track of the metal antennas 128a, 128b and 128c. The distance changes. That is, when the track is tilted counterclockwise about the tip position 171a of the metal antenna 128a, the distance P1 between the tip position 171b of the metal antenna 128b and the track center is increased, and the tip position of the metal antenna 128c is increased. The distance P2 between 171c and the track center is increased.
　図３７は、Ｐ１＝Ｐ２＝Ｔｐ／４の場合におけるトラックからの位置ずれに対する検出信号ｔｅ１及びｔｅ２の強度変化を示す図である。それぞれの検出信号ｔｅ１及びｔｅ２の初期値はｔｅ１０及びｔｅ２０である。トラックの角度に変化がない場合には、検出信号ｔｅ１及び検出信号ｔｅ２のトラック位置ずれに対する位相差がπラジアンであるため、２つの検出信号の和（ｔｅ１＋ｔｅ２）はトラックからの位置ずれによらず一定値（ｔｅ１０＋ｔｅ２０）となる。このため、トラックからの位置ずれに関わらずヨーイング信号ＹＥ２の基準値として、初期値ｔｅ１０及びｔｅ２０の和（ｔｅ１０＋ｔｅ２０）を用いることができる。 FIG. 37 is a diagram showing intensity changes of the detection signals te1 and te2 with respect to the positional deviation from the track in the case of P1 = P2 = Tp / 4. The initial values of the detection signals te1 and te2 are te1 0 and te2 0 , respectively. When there is no change in the track angle, the phase difference of the detection signal te1 and the detection signal te2 with respect to the track position shift is π radians. It becomes a constant value (te1 0 + te2 0 ). For this reason, the sum (te1 0 + te2 0 ) of the initial values te1 0 and te2 0 can be used as the reference value of the yawing signal YE2 regardless of the positional deviation from the track.
　図３８は、Ｐ１＝Ｐ２＝Ｔｐ／４の場合におけるトラック中心と金属アンテナ１２８ｂ及び１２８ｃの先端との距離に対する検出信号ｔｅ１及びｔｅ２の強度変化を示す図である。トラックにずれがない状態では、Ｐ１＝Ｐ２＝Ｔｐ／４であるため、検出信号ｔｅ１及びｔｅ２の強度は、白丸印で表される値となる。 FIG. 38 is a diagram showing changes in the intensity of the detection signals te1 and te2 with respect to the distance between the track center and the tips of the metal antennas 128b and 128c when P1 = P2 = Tp / 4. In a state where there is no deviation in the track, since P1 = P2 = Tp / 4, the intensities of the detection signals te1 and te2 are values represented by white circles.
　トラックが時計回り（ｃｗ）に回転した場合は、金属アンテナ１２８ｂ及び１２８ｃは共にトラック中心に近づき、検出信号ｔｅ１及びｔｅ２の強度は、図３８中のｃｗ方向へシフトして、白四角印で表される値となる。このため、時計回りにトラックの角度が変化した場合には、検出信号ｔｅ１及びｔｅ２は共に減少する。 When the track is rotated clockwise (cw), both the metal antennas 128b and 128c approach the track center, and the intensity of the detection signals te1 and te2 is shifted in the cw direction in FIG. It becomes the value to be. For this reason, when the track angle changes clockwise, the detection signals te1 and te2 both decrease.
　逆に、トラックが反時計回り（ｃｃｗ）に回転した場合は、金属アンテナ１２８ｂ及び１２８ｃは共にトラック中心から遠ざかり、検出信号ｔｅ１及びｔｅ２の強度は、図３８中のｃｃｗ方向へシフトして、白三角印で表される値となる。このため、反時計回り（ｃｃｗ）にトラックの角度が変化した場合には、検出信号ｔｅ１及びｔｅ２は共に増加する。 Conversely, when the track rotates counterclockwise (ccw), both the metal antennas 128b and 128c move away from the track center, and the intensity of the detection signals te1 and te2 shifts in the ccw direction in FIG. The value is represented by a triangle. For this reason, when the track angle changes counterclockwise (ccw), both the detection signals te1 and te2 increase.
　図３９は、Ｐ１＝Ｐ２＝Ｔｐ／４の場合におけるトラック角度変化に対する検出信号ｔｅ１及びｔｅ２の初期値ｔｅ１０及びｔｅ２０からの変化量とヨーイング信号ＹＥ２（ＹＥ２＝（ｔｅ１＋ｔｅ２）－（ｔｅ１０＋ｔｅ２０））の変化とを示す図である。 Figure 39 is, P1 = P2 = Tp / 4 of variation and yawing signal from the initial value te1 0 and te2 0 of the detection signal te1 and te2 for the track angle changes when YE2 (YE2 = (te1 + te2 ) - (te1 0 + te2 It is a figure which shows the change of 0 )).
　ヨーイング信号ＹＥ２は、原点でゼロクロスする誤差信号となっている。また、基準値として用いる初期値ｔｅ１０及びｔｅ２０の和（ｔｅ１０＋ｔｅ２０）は、トラックからの位置ずれに対して変化しない。そのため、トラックから外れた状態であってもヨーイング信号ＹＥ２を生成することができる。ヨーイング信号ＹＥ２に基づいて、スライダ１４１の傾きが制御されることで、金属アンテナ１２８ｂ及び１２８ｃ間のトラックに垂直な方向の距離は、トラッキング周期Ｔｐの半分に保つことができる。 The yawing signal YE2 is an error signal that zero-crosses at the origin. Further, the sum (te1 0 + te2 0 ) of the initial values te1 0 and te2 0 used as the reference value does not change with respect to the positional deviation from the track. For this reason, the yawing signal YE2 can be generated even when the track is off the track. By controlling the tilt of the slider 141 based on the yawing signal YE2, the distance in the direction perpendicular to the track between the metal antennas 128b and 128c can be maintained at half the tracking period Tp.
　次に、ヨーイング信号ＹＥ２の生成原理について、金属アンテナ１２８ｂとトラック中心との間のトラックに垂直な方向の距離Ｐ１と、金属アンテナ１２８ｃとトラック中心との間のトラックに垂直な方向の距離Ｐ２とが異なる（Ｐ１≠Ｐ２）場合について、図４０～図４４を用いて説明する。 Next, regarding the generation principle of the yawing signal YE2, the distance P1 in the direction perpendicular to the track between the metal antenna 128b and the track center, and the distance P2 in the direction perpendicular to the track between the metal antenna 128c and the track center, Are different (P1 ≠ P2) will be described with reference to FIGS.
　図４０は、Ｐ１≠Ｐ２の場合におけるトラック角度変化について説明するための概念図である。３つの金属アンテナ１２８ａ、１２８ｂ及び１２８ｃが正確に一直線に並んでいない場合、図４０に示すようなアンバランスな配置になりえる。図４０に示すように、ディスク１０１の偏心又はモータ１４３とサスペンション１４２とを用いたトラックに垂直な方向への移動によりトラック角度が変化すると、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃのトラックに垂直な方向の距離が変化する。すなわち、金属アンテナ１２８ａの先端位置１７１ａを中心にしてトラックが反時計回りに傾くことにより、金属アンテナ１２８ｂの先端位置１７１ｂとトラック中心との間の距離Ｐ１は、大きくなり、金属アンテナ１２８ｃの先端位置１７１ｃとトラック中心との間の距離Ｐ２は、大きくなる。 FIG. 40 is a conceptual diagram for explaining the track angle change in the case of P1 ≠ P2. If the three metal antennas 128a, 128b, and 128c are not accurately aligned, an unbalanced arrangement as shown in FIG. 40 can be obtained. As shown in FIG. 40, when the track angle changes due to the eccentricity of the disk 101 or the movement in the direction perpendicular to the track using the motor 143 and the suspension 142, the direction perpendicular to the track of the metal antennas 128a, 128b and 128c. The distance changes. That is, when the track is tilted counterclockwise about the tip position 171a of the metal antenna 128a, the distance P1 between the tip position 171b of the metal antenna 128b and the track center is increased, and the tip position of the metal antenna 128c is increased. The distance P2 between 171c and the track center is increased.
　図４１は、Ｐ１≠Ｐ２の場合におけるトラックからの位置ずれに対する検出信号ｔｅ１及びｔｅ２の強度変化を示す図である。それぞれの検出信号ｔｅ１及びｔｅ２の初期値はｔｅ１０とｔｅ２０である。トラックの角度に変化がない場合には、検出信号ｔｅ１及び検出信号ｔｅ２のトラック位置ずれに対する位相差がπラジアンであるため、２つの検出信号の平均（（ｔｅ１＋ｔｅ２）／２）はトラックからの位置ずれによらず一定値（（ｔｅ１０＋ｔｅ２０）／２）となる。このため、トラックからの位置ずれに関わらずヨーイング信号ＹＥ２の基準値として、初期値ｔｅ１０及びｔｅ２０の和（ｔｅ１０＋ｔｅ２０）を用いることができる。 FIG. 41 is a diagram showing changes in the intensity of the detection signals te1 and te2 with respect to the positional deviation from the track when P1 ≠ P2. The initial values of the detection signals te1 and te2 are te1 0 and te2 0 , respectively. When there is no change in the track angle, the phase difference of the detection signal te1 and the detection signal te2 with respect to the track position deviation is π radians, so the average of the two detection signals ((te1 + te2) / 2) It becomes a constant value ((te1 0 + te2 0 ) / 2) regardless of the deviation. For this reason, the sum (te1 0 + te2 0 ) of the initial values te1 0 and te2 0 can be used as the reference value of the yawing signal YE2 regardless of the positional deviation from the track.
　図４２は、Ｐ１≠Ｐ２の場合におけるトラック中心と金属アンテナ１２８ｂ及び１２８ｃの先端との距離に対する検出信号ｔｅ１及びｔｅ２の強度変化を示す図である。トラックにずれがない状態では、検出信号ｔｅ１及びｔｅ２の強度は、白丸印で表される値となる。 FIG. 42 is a diagram showing changes in the intensity of the detection signals te1 and te2 with respect to the distance between the track center and the tips of the metal antennas 128b and 128c when P1 ≠ P2. In a state where there is no deviation in the track, the strengths of the detection signals te1 and te2 are values represented by white circles.
　トラックが時計回り（ｃｗ）に回転した場合は、検出信号ｔｅ１及びｔｅ２の強度は、図４２中のｃｗ方向へシフトして、白四角印で表される値となる。逆に、トラックが反時計回り（ｃｃｗ）に回転した場合は、検出信号ｔｅ１及びｔｅ２の強度は、図４２中のｃｃｗ方向へシフトして、白三角印で表される値となる。 When the track rotates clockwise (cw), the intensity of the detection signals te1 and te2 shifts in the cw direction in FIG. 42 and becomes a value represented by a white square mark. Conversely, when the track rotates counterclockwise (ccw), the intensity of the detection signals te1 and te2 shifts in the ccw direction in FIG. 42 and becomes a value represented by a white triangle.
　図４３は、Ｐ１≠Ｐ２の場合におけるトラック角度変化に対する検出信号ｔｅ１及びｔｅ２の初期値の平均（（ｔｅ１０＋ｔｅ２０）／２）からの変化量とヨーイング信号ＹＥ２（ＹＥ２＝（ｔｅ１＋ｔｅ２）－（ｔｅ１０＋ｔｅ２０））の変化とを示す図である。 FIG. 43 shows the amount of change from the average ((te1 0 + te2 0 ) / 2) of the initial values of the detection signals te1 and te2 with respect to the track angle change in the case of P1 ≠ P2, and the yawing signal YE2 (YE2 = (te1 + te2) − ( te1 0 + te2 0 )).
　トラック中心と金属アンテナ１２８ｂ及び１２８ｃの中点とに位置ずれがある場合、検出信号ｔｅ１及びｔｅ２のトラック角度変化に対する位相は、それぞれ逆方向に等量だけシフトする。このとき、ヨーイング信号ＹＥ２（ＹＥ２＝（ｔｅ１＋ｔｅ２）－（ｔｅ１０＋ｔｅ２０））は、正及び負に等位相ずれた２つの信号の合成信号となる。このため、ヨーイング信号ＹＥ２は、常に原点でゼロクロスする誤差信号となり、Ｐ１≠Ｐ２の場合でもヨーイング信号ＹＥ２を生成することができる。 When there is a positional shift between the track center and the midpoints of the metal antennas 128b and 128c, the phases of the detection signals te1 and te2 with respect to changes in the track angle are shifted by the same amount in the opposite direction. At this time, the yawing signal YE2 (YE2 = (te1 + te2) − (te1 0 + te2 0 )) is a composite signal of two signals that are shifted in phase by positive and negative. Therefore, the yawing signal YE2 is always an error signal that crosses zero at the origin, and the yawing signal YE2 can be generated even when P1 ≠ P2.
　また、基準値として用いる初期値ｔｅ１０及びｔｅ２０の和（ｔｅ１０＋ｔｅ２０）は、トラックからの位置ずれに対して変化しない。そのため、トラックから外れた状態であってもヨーイング信号ＹＥ２を生成することができる。 Further, the sum (te1 0 + te2 0 ) of the initial values te1 0 and te2 0 used as the reference value does not change with respect to the positional deviation from the track. For this reason, the yawing signal YE2 can be generated even when the track is off the track.
　図４４は、Ｐ１≠Ｐ２の場合におけるトラック中心と金属アンテナ１２８ｂ及び１２８ｃの先端の中点との距離に対するヨーイング信号ＹＥ２の感度を示す図である。トラック角度変化が０の状態におけるヨーイング信号ＹＥ２のトラック角度変化に対する感度は、図４４のように変化する。ヨーイング信号ＹＥ２の感度は、トラック中心と金属アンテナ１２８ｂ及び１２８ｃ先端の中点とが一致する場合に最大となり、トラック中心と金属アンテナ１２８ｂ及び１２８ｃ先端の中点との距離がＴｐ／４となる場合に０となる。ヨーイング信号ＹＥ２に基づいて、スライダ１４１の傾きが制御されることで、Ｐ１≠Ｐ２の場合でも金属アンテナ１２８ｂ及び１２８ｃ間のトラックに垂直な方向の距離は、トラッキング周期Ｔｐの半分に保つことができる。 FIG. 44 is a diagram showing the sensitivity of the yawing signal YE2 with respect to the distance between the track center and the midpoints of the tips of the metal antennas 128b and 128c when P1 ≠ P2. The sensitivity of the yawing signal YE2 to the change in the track angle when the change in the track angle is 0 changes as shown in FIG. The sensitivity of the yawing signal YE2 is maximum when the track center and the midpoint of the tips of the metal antennas 128b and 128c coincide, and the distance between the track center and the midpoint of the tips of the metal antennas 128b and 128c is Tp / 4. 0. By controlling the tilt of the slider 141 based on the yawing signal YE2, the distance in the direction perpendicular to the track between the metal antennas 128b and 128c can be kept at half the tracking period Tp even when P1 ≠ P2. .
　以上のように、本実施の形態４の光情報装置において、ヨーイング信号演算回路１５１は、共鳴素子の共鳴状態の変化に基づいてヨーイング信号を得る。また、ピエゾ素子１４４ａ及び１４４ｂは、ヨーイング信号に応じて保持素子（スライダ１４１）を情報記録媒体の表面に平行な面内で回転させる。 As described above, in the optical information device according to the fourth embodiment, the yawing signal calculation circuit 151 obtains a yawing signal based on the change in the resonance state of the resonance element. The piezo elements 144a and 144b rotate the holding element (slider 141) in a plane parallel to the surface of the information recording medium according to the yawing signal.
　図４５は、図３０に示すトラッキング信号演算回路１６１の構成を示す図である。トラッキング信号演算回路１６１は、補正値演算回路１６２、第１の差分回路１６３ａ、第２の差分回路１６３ｂ、重み付き差分回路１６４及び制御回路１６５を備える。 45 is a diagram showing a configuration of the tracking signal arithmetic circuit 161 shown in FIG. The tracking signal calculation circuit 161 includes a correction value calculation circuit 162, a first difference circuit 163a, a second difference circuit 163b, a weighted difference circuit 164, and a control circuit 165.
　なお、図４５では、金属アンテナ１２８ａの先端位置１７１ａがトラックの中心上にある場合の金属アンテナ１２８ｂの先端位置１７１ｂ及び金属アンテナ１２８ｃの先端位置１７１ｃの位置ずれを示している。また、図４５では、金属アンテナ１２８ａの先端位置１７１ａ、金属アンテナ１２８ｂの先端位置１７１ｂ及び金属アンテナ１２８ｃの先端位置１７１ｃから検出信号ｔｅ０、ｔｅ１及びｔｅ２が出力されているように記載しているが、実際には、検出信号ｔｅ０、ｔｅ１及びｔｅ２は、受光素子１２０ａ、１２０ｂ及び１２０ｃから出力される。 Note that FIG. 45 shows a positional shift between the tip position 171b of the metal antenna 128b and the tip position 171c of the metal antenna 128c when the tip position 171a of the metal antenna 128a is on the center of the track. In FIG. 45, the detection signals te0, te1, and te2 are output from the tip position 171a of the metal antenna 128a, the tip position 171b of the metal antenna 128b, and the tip position 171c of the metal antenna 128c. Actually, the detection signals te0, te1, and te2 are output from the light receiving elements 120a, 120b, and 120c.
　まず、モータ１４３は、スライダ１４１をトラックに垂直な方向に走査する。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの共鳴強度に対応した検出信号ｔｅ０、ｔｅ１及びｔｅ２は、図１３（Ａ）に示すように、トラックからの距離に対して周期的に変化する。検出信号ｔｅ０、ｔｅ１及びｔｅ２は、補正値演算回路１６２に入力される。補正値演算回路１６２は、検出信号ｔｅ０、ｔｅ１及びｔｅ２に基づいて補正値ａ及びｂを決定する。なお、補正値ａ及びｂの決定方法については後で述べる。補正値が決定された後、モータ１４３は、トラックに垂直な方向へのスライダ１４１の走査を停止する。 First, the motor 143 scans the slider 141 in a direction perpendicular to the track. The detection signals te0, te1, and te2 corresponding to the resonance intensities of the metal antennas 128a, 128b, and 128c periodically change with respect to the distance from the track, as shown in FIG. The detection signals te0, te1 and te2 are input to the correction value calculation circuit 162. The correction value calculation circuit 162 determines correction values a and b based on the detection signals te0, te1, and te2. A method for determining the correction values a and b will be described later. After the correction value is determined, the motor 143 stops scanning the slider 141 in the direction perpendicular to the track.
　第１の差分回路１６３ａは、検出信号ｔｅ１と検出信号ｔｅ０との差分（ｔｅ１－ｔｅ０）を生成し、重み付き差分回路１６４に出力する。また、第２の差分回路１６３ｂは、検出信号ｔｅ２と検出信号ｔｅ０との差分（ｔｅ２－ｔｅ０）を生成し、重み付き差分回路１６４に出力する。 The first difference circuit 163a generates a difference (te1-te0) between the detection signal te1 and the detection signal te0 and outputs the difference to the weighted difference circuit 164. The second difference circuit 163b generates a difference (te2−te0) between the detection signal te2 and the detection signal te0 and outputs the difference to the weighted difference circuit 164.
　重み付き差分回路１６４は、補正値演算回路１６２によって決定された補正値ａ及びｂ、第１の差分回路１６３ａによって算出された差分、及び第２の差分回路１６３ｂによって算出された差分を用いて、トラッキング信号ＴＥ（ＴＥ＝ａ×（ｔｅ１－ｔｅ０）－ｂ×（ｔｅ２－ｔｅ０））を生成する。 The weighted difference circuit 164 uses the correction values a and b determined by the correction value calculation circuit 162, the difference calculated by the first difference circuit 163a, and the difference calculated by the second difference circuit 163b. A tracking signal TE (TE = a × (te1-te0) −b × (te2-te0)) is generated.
　制御回路１６５は、トラッキング信号ＴＥに基づいて金属アンテナ１２８ａをトラッキングするようにモータ１４３を制御する制御信号を出力する。 The control circuit 165 outputs a control signal for controlling the motor 143 so as to track the metal antenna 128a based on the tracking signal TE.
　次に、補正値ａ及びｂの決定方法について説明する。検出信号ｔｅ０、ｔｅ１及びｔｅ２が、トラックからの位置ずれ量ｘに対してそれぞれ下記の式（１）～（３）のように変化すると仮定する。 Next, a method for determining the correction values a and b will be described. It is assumed that the detection signals te0, te1, and te2 change according to the following equations (1) to (3) with respect to the positional deviation amount x from the track.
Figure JPOXMLDOC01-appb-I000001
Figure JPOXMLDOC01-appb-I000001
　なお、上記の式（１）～（３）において、ｘは、トラックからの位置ずれ量を表し、αは、検出信号ｔｅ１の検出信号ｔｅ０に対する位相差を表し、βは、検出信号ｔｅ２の検出信号ｔｅ０に対する位相差を表し、γは、オフセットを表す。 In the above equations (1) to (3), x represents the amount of positional deviation from the track, α represents the phase difference of the detection signal te1 from the detection signal te0, and β represents the detection of the detection signal te2. The phase difference with respect to the signal te0 is represented, and γ represents an offset.
　検出信号ｔｅ０、ｔｅ１及びｔｅ２を上記の式（１）～（３）のように表すと、トラッキング信号ＴＥは下記の式（４）のように表される。 When the detection signals te0, te1 and te2 are expressed as the above formulas (1) to (3), the tracking signal TE is expressed as the following formula (4).
Figure JPOXMLDOC01-appb-I000002
Figure JPOXMLDOC01-appb-I000002
　トラックからの位置ずれ量ｘが０（ｘ＝０）のときにトラッキング信号ＴＥがゼロクロスするためには、上記の式（４）の右辺の第一項の係数が０となればよい。つまり、補正値ａ及びｂは、下記の式（５）の関係を満たせばよい。 In order for the tracking signal TE to zero-cross when the positional deviation amount x from the track is 0 (x = 0), the coefficient of the first term on the right side of the above equation (4) may be 0. That is, the correction values a and b may satisfy the relationship of the following formula (5).
Figure JPOXMLDOC01-appb-I000003
Figure JPOXMLDOC01-appb-I000003
　補正値ａ及びｂが上記の式（５）の条件を満たす場合、上記の式（４）の右辺の第一項の係数が０となるので、トラッキング信号ＴＥは、上記の式（４）の右辺の第二項のみで表される。このとき、トラッキング信号ＴＥの信号振幅は、上記の式（４）の右辺の第二項の係数により決まる。補正値演算回路１６２は、補正値ａを下記の式（６）に基づいて決定することにより、上記の式（４）の右辺の第二項の係数は“２”となり、信号振幅が“２”のトラッキング信号ＴＥが得られる。 When the correction values a and b satisfy the condition of the above equation (5), the coefficient of the first term on the right side of the above equation (4) is 0, so that the tracking signal TE is expressed by the above equation (4). It is represented only by the second term on the right side. At this time, the signal amplitude of the tracking signal TE is determined by the coefficient of the second term on the right side of the above equation (4). The correction value calculation circuit 162 determines the correction value a based on the following equation (6), whereby the coefficient of the second term on the right side of the above equation (4) is “2” and the signal amplitude is “2”. "Is obtained.
Figure JPOXMLDOC01-appb-I000004
Figure JPOXMLDOC01-appb-I000004
　このように、補正値ａ及びｂが決定されることで、任意の位置に配置され、トラックに垂直な方向の距離Ｐ１及びＰ２がＰ１≠Ｐ２となる金属アンテナ１２８ａ、１２８ｂ及び１２８ｃについて、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃをトラックに垂直な方向の距離Ｐ１及びＰ２がＰ１＝Ｐ２＝Ｔｐ／４となるように配置した場合と同様のトラッキング信号ＴＥを生成することができる。 As described above, by determining the correction values a and b, the metal antennas 128a, 128b, and 128c that are arranged at arbitrary positions and that have distances P1 and P2 in the direction perpendicular to the track satisfying P1 ≠ P2 are used. It is possible to generate a tracking signal TE similar to the case where 128a, 128b and 128c are arranged such that the distances P1 and P2 in the direction perpendicular to the track are P1 = P2 = Tp / 4.
　図４６（Ａ）は、トラックからの位置ずれに対する検出信号ｔｅ１と検出信号ｔｅ０との差分に補正値ａを重み付けした信号（ａ×（ｔｅ１－ｔｅ０））及び検出信号ｔｅ２と検出信号ｔｅ０との差分に補正値ｂを重み付けした信号（ｂ×（ｔｅ２－ｔｅ０））の強度変化を示すグラフである。ａ×（ｔｅ１－ｔｅ０）の強度及びｂ×（ｔｅ２－ｔｅ０）の強度は、それぞれトラックからの位置ずれに対してトラッキング周期Ｔｐで周期的に変化し、補正値ａ及びｂによってトラックからの位置ずれが０となる位置で互いに等しい値となる。 FIG. 46A shows a signal (a × (te1−te0)) obtained by weighting the difference between the detection signal te1 and the detection signal te0 with respect to the positional deviation from the track and the detection signal te2 and the detection signal te0. It is a graph which shows the intensity | strength change of the signal (bx (te2-te0)) which weighted the difference with the correction value b. The intensity of a × (te1-te0) and the intensity of b × (te2-te0) periodically change in the tracking period Tp with respect to the positional deviation from the track, and the position from the track by the correction values a and b. At positions where the deviation is 0, the values are equal to each other.
　図４６（Ｂ）は、トラックからの位置ずれに対するトラッキング信号ＴＥの強度変化を示すグラフである。トラッキング信号ＴＥは、トラックからの位置ずれが０のときにゼロクロスし、トラックからの位置ずれに比例する。トラッキング信号ＴＥに基づいてモータ１４３が制御されてトラッキングが行われる。かかる構成により、記録又は再生用の金属アンテナ１２８ａを微粒子１０２に対して、安定かつ高精度にトラッキングすることができる。 FIG. 46B is a graph showing a change in intensity of the tracking signal TE with respect to a positional deviation from the track. The tracking signal TE is zero-crossed when the positional deviation from the track is zero, and is proportional to the positional deviation from the track. Tracking is performed by controlling the motor 143 based on the tracking signal TE. With this configuration, the recording or reproducing metal antenna 128a can be stably and accurately tracked with respect to the fine particles 102.
　なお、本実施の形態４において、半導体レーザ素子１０７ａ，１０７ｂ，１０７ｃが光源の一例に相当し、金属アンテナ１２８ａ，１２８ｂ，１２８ｃが複数の共鳴素子の一例に相当し、スライダ１４１が保持素子の一例に相当し、受光素子１２０ａ，１２０ｂ，１２０ｃが第１の検出素子及び複数の受光素子の一例に相当し、モータ１０３が第１の移動素子の一例に相当し、サスペンション１４２が第２の移動素子の一例に相当し、トラッキング信号演算回路１６１がトラッキング信号演算回路の一例に相当し、ヨーイング信号演算回路１５１がヨーイング信号演算回路の一例に相当し、ピエゾ素子１４４ａ，１４４ｂが回転素子の一例に相当する。 In the fourth embodiment, the semiconductor laser elements 107a, 107b, and 107c correspond to an example of a light source, the metal antennas 128a, 128b, and 128c correspond to an example of a plurality of resonance elements, and the slider 141 is an example of a holding element. The light receiving elements 120a, 120b, and 120c correspond to an example of the first detection element and the plurality of light receiving elements, the motor 103 corresponds to an example of the first moving element, and the suspension 142 corresponds to the second moving element. The tracking signal calculation circuit 161 corresponds to an example of a tracking signal calculation circuit, the yawing signal calculation circuit 151 corresponds to an example of a yawing signal calculation circuit, and the piezo elements 144a and 144b correspond to an example of a rotation element. To do.
　このように、本実施の形態４では、ハードディスクドライブに採用されるフライングヘッドと同様の技術を用いることで、スライダ１４１とディスク１０１とが接触することなく、スライダ１４１は、ディスク１０１上の数ｎｍ～数十ｎｍの位置においてディスク１０１を走査することができる。そのため、ディスク１０１及びスライダ１４１がそれぞれ磨耗を起こさずに精密なギャップ制御を行うことができる。 As described above, in the fourth embodiment, by using the same technique as the flying head employed in the hard disk drive, the slider 141 and the disk 101 are not in contact with each other, and the slider 141 is several nm on the disk 101. The disk 101 can be scanned at a position of ˜tens of nm. Therefore, precise gap control can be performed without causing the disk 101 and the slider 141 to wear.
　また、本実施の形態４では、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、それぞれトラックの長手方向にずらして配置される。すなわち、スライダ１４１は、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの位置をトラックの長手方向にずらして配置する。これにより、隣接する金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの間の相互作用を抑制でき、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの形状の自由度が高くなる。 In the fourth embodiment, the metal antennas 128a, 128b, and 128c are arranged so as to be shifted in the longitudinal direction of the track. That is, the slider 141 is arranged by shifting the positions of the metal antennas 128a, 128b and 128c in the longitudinal direction of the track. Thereby, the interaction between the adjacent metal antennas 128a, 128b, and 128c can be suppressed, and the degree of freedom of the shape of the metal antennas 128a, 128b, and 128c is increased.
　さらに、複数の共鳴素子（金属アンテナ１２８ａ、１２８ｂ及び金属アンテナ１２８ｃ）のトラックの長手方向の位置ずれが、複数の共鳴素子（金属アンテナ１２８ａ、１２８ｂ又は金属アンテナ１２８ｃ）のうちの１つの共鳴素子のトラックの長手方向の厚さ以上にずれていても良い。これにより、複数の共鳴素子間の相互作用をより抑制できる。 Further, the positional deviation in the longitudinal direction of the tracks of the plurality of resonance elements ( metal antennas 128a, 128b and metal antenna 128c) is caused by the resonance of one resonance element of the plurality of resonance elements ( metal antenna 128a, 128b or metal antenna 128c). It may be shifted beyond the thickness in the longitudinal direction of the track. Thereby, the interaction between a plurality of resonant elements can be further suppressed.
　また、本実施の形態４では、近接場光ではなく反射光が検出される。これにより、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの直近に微小な受光素子１１０ａ、１１０ｂ及び１１０ｃを作製する必要がなくなり、光情報装置の作製が容易になる。 In the fourth embodiment, reflected light is detected instead of near-field light. This eliminates the need to fabricate minute light receiving elements 110a, 110b, and 110c in the immediate vicinity of the metal antennas 128a, 128b, and 128c, and facilitates fabrication of the optical information device.
　また、本実施の形態４では、受光素子１２０ａ、１２０ｂ及び１２０ｃは、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃと相互作用することがない。このため、効率よく金属アンテナ１２８ａ、１２８ｂ及び１２８ｃとディスク１０１とを相互作用させることができ、効率よくトラッキング及び情報の記録又は再生を行うことができる。 In the fourth embodiment, the light receiving elements 120a, 120b, and 120c do not interact with the metal antennas 128a, 128b, and 128c. For this reason, the metal antennas 128a, 128b, and 128c and the disk 101 can be efficiently interacted, and tracking and information recording or reproduction can be performed efficiently.
　また、本実施の形態４では、ヨーイング信号演算回路１５１により、共鳴素子の共鳴状態の変化に基づいてヨーイング信号が生成され、ピエゾ素子１４４ａ及び１４４ｂにより、ヨーイング信号に応じてスライダ１４１（保持素子）をディスク１０１の表面に平行な面内で回転させる。このため、ディスク１０１の偏心又はモータ１４３とサスペンション１４２とを用いたトラックに垂直な方向への移動によるトラック角度変化に対して、共鳴素子（金属アンテナ１２８ｂ及び１２８ｃ）のトラックに垂直な方向の距離が一定に保持される。したがって、安定したトラッキングを行うことができる。 In the fourth embodiment, a yawing signal calculation circuit 151 generates a yawing signal based on a change in the resonance state of the resonance element, and piezoelectric elements 144a and 144b use slider 141 (holding element) according to the yawing signal. Is rotated in a plane parallel to the surface of the disk 101. Therefore, the distance in the direction perpendicular to the track of the resonant elements ( metal antennas 128b and 128c) with respect to the change in the track angle due to the eccentricity of the disk 101 or the movement in the direction perpendicular to the track using the motor 143 and the suspension 142. Is held constant. Therefore, stable tracking can be performed.
　また、本実施の形態４では、トラッキング信号演算回路１６１は、検出信号ｔｅ０、ｔｅ１及びｔｅ２から補正値ａ及びｂを演算し、検出信号の差分値（ｔｅ１－ｔｅ０）と補正値ａとの積と、検出信号の差分値（ｔｅ２－ｔｅ０）と補正値ｂとの積との差をトラッキング信号ＴＥとして出力する。このため、記録又は再生用の金属アンテナ１２８ａから任意の距離に配置されたトラッキング用の金属アンテナ１２８ｂ及び１２８ｃを用いてトラッキング信号を得ることができる。したがって、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃのそれぞれの間隔に対する制約がなくなり、光情報装置の作製が容易となる。 In the fourth embodiment, the tracking signal calculation circuit 161 calculates the correction values a and b from the detection signals te0, te1 and te2, and the product of the difference value (te1-te0) of the detection signal and the correction value a. And the difference between the product of the difference value (te2-te0) of the detection signal and the correction value b is output as the tracking signal TE. Therefore, a tracking signal can be obtained using the tracking metal antennas 128b and 128c arranged at an arbitrary distance from the recording or reproducing metal antenna 128a. Therefore, there are no restrictions on the distances between the metal antennas 128a, 128b, and 128c, and the fabrication of the optical information device is facilitated.
　なお、本実施の形態４では、半導体レーザ素子及び受光素子のペアが、１本の導波路に対して隣接して配置されているが、例えば、Ｙ字導波路を用いてもよい。この場合、Ｙ字導波路の一方に半導体レーザ素子を配置し、他方に受光素子を配置してもよい。このように、光の出射位置と反射光の検出位置とを分離する構成にしても、本発明の主旨が損なわれるものではない。 In the fourth embodiment, the pair of the semiconductor laser element and the light receiving element is disposed adjacent to one waveguide, but for example, a Y-shaped waveguide may be used. In this case, a semiconductor laser element may be disposed on one side of the Y-shaped waveguide, and a light receiving element may be disposed on the other side. Thus, even if it is the structure which isolate | separates the light emission position and the detection position of reflected light, the main point of this invention is not impaired.
　また、本実施の形態４では、スライダ１４１の端面に階段状の段差が形成され、各段に金属アンテナ１２８ａ、１２８ｂ及び１２８ｃが配置されているが、本発明は特にこれに限定されない。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、互いに相互作用しないように、トラックの長手方向にずれて配置されていればよい。例えば、図１４及び図１５に示すように、スライダ１４１の端面は、凸形状又は凹形状であってもよい。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、トラックの長手方向にずれて配置される。 In the fourth embodiment, a stepped step is formed on the end surface of the slider 141, and the metal antennas 128a, 128b, and 128c are arranged on each step. However, the present invention is not particularly limited to this. The metal antennas 128a, 128b, and 128c only need to be shifted in the longitudinal direction of the track so as not to interact with each other. For example, as shown in FIGS. 14 and 15, the end surface of the slider 141 may be convex or concave. The metal antennas 128a, 128b and 128c are arranged so as to be shifted in the longitudinal direction of the track.
　また、本実施の形態４では、スライダ１４１とエアスライダ１３２とは別々の構成としているが、本発明は特にこれに限定されず、スライダ１４１を大きくしてもよい。スライダ１４１は、ディスク１０１の表面に垂直な方向にスライダ１４１を移動させるエアスライダの機能を兼ね備えてもよい。この場合も、本発明の主旨が損なわれるものではない。 In the fourth embodiment, the slider 141 and the air slider 132 are configured separately, but the present invention is not particularly limited to this, and the slider 141 may be enlarged. The slider 141 may also have the function of an air slider that moves the slider 141 in a direction perpendicular to the surface of the disk 101. Also in this case, the gist of the present invention is not impaired.
　また、実施の形態４では、モータ１４３とサスペンション１４２とを用いてスライダ１４１をトラックに垂直な方向に移動させているが、実施の形態１及び２のようにモータ１４３の代わりにアクチュエータを用いて、サスペンション１４２をトラックに垂直な方向に移動させてもよい。 In the fourth embodiment, the slider 141 is moved in the direction perpendicular to the track using the motor 143 and the suspension 142. However, as in the first and second embodiments, an actuator is used instead of the motor 143. The suspension 142 may be moved in a direction perpendicular to the track.
　また、実施の形態４では、情報を記録又は再生するために相変化材料で構成された微粒子を用いているが、本発明は特にこれに限定されない。光情報装置が、例えばＲＯＭ装置のような再生のみを行う光情報装置である場合は、微粒子の代わりに、凹凸形状のピットを用いてもよく、又は金属パターンなどを用いてもよい。 In the fourth embodiment, fine particles made of a phase change material are used for recording or reproducing information, but the present invention is not particularly limited to this. When the optical information device is an optical information device that performs only reproduction, such as a ROM device, for example, uneven pits may be used instead of fine particles, or metal patterns may be used.
　また、実施の形態４では、金属アンテナの形状は三角平板形状であるが、金属アンテナの形状は上記の例に特に限定されず、例えば三角平板形状以外にも図１７～図１９に示すような形状も考えられる。金属アンテナの形状は、微粒子上でプラズモン共鳴し、トラックからの距離に応じて効率よくプラズモン共鳴状態が変化するものであれば、特に限定されるものではない。図１７のように、金属アンテナ１１７の形状が四角平板形状である場合、金属アンテナ１１７は上下対称であるため三角平板形状と比較して解析が容易である。また、図１８のように、金属アンテナ１１８の形状が円板形状である場合、パターンの作製が三角平板形状に比べて容易である。また、図１９のように、金属アンテナ１１９の形状がプローブ形状である場合、より効率的にプローブの先端に近接場光を発生させることができる。 In the fourth embodiment, the shape of the metal antenna is a triangular plate shape. However, the shape of the metal antenna is not particularly limited to the above example. For example, as shown in FIGS. A shape is also conceivable. The shape of the metal antenna is not particularly limited as long as plasmon resonance occurs on the fine particles and the plasmon resonance state efficiently changes according to the distance from the track. As shown in FIG. 17, when the shape of the metal antenna 117 is a square flat plate shape, the metal antenna 117 is vertically symmetric, so that the analysis is easier than the triangular flat plate shape. Further, as shown in FIG. 18, when the shape of the metal antenna 118 is a disc shape, the pattern can be easily produced as compared with the triangular plate shape. Further, as shown in FIG. 19, when the shape of the metal antenna 119 is a probe shape, near-field light can be generated more efficiently at the tip of the probe.
　また、実施の形態４では、２つのトラッキング用の金属アンテナを備えているが、金属アンテナの本数及び配置方法は、トラック位置において複数のトラッキング用の金属アンテナからの検出信号の差が０となり、トラックからの位置ずれに応じて検出信号の差が得られるものであればよい。トラッキング用の金属アンテナの本数及び配置方法は、本実施の形態４で示した構成に特に限定されるものではない。 In the fourth embodiment, two tracking metal antennas are provided. However, in the number and arrangement method of the metal antennas, the difference between detection signals from a plurality of tracking metal antennas is 0 at the track position. What is necessary is just to be able to obtain a difference in detection signal according to the positional deviation from the track. The number of metal antennas for tracking and the arrangement method are not particularly limited to the configuration shown in the fourth embodiment.
　また、実施の形態４では、導波モード結合を抑制するために複数の導波路１２９ａ～１２９ｃは互いに非平行に配置されるが、導波モード結合が起こらない構成であれば、複数の導波路１２９ａ～１２９ｃを互いに平行に配置してもよく、これにより、本発明の主旨が損なわれるものではない。 In the fourth embodiment, the plurality of waveguides 129a to 129c are arranged non-parallel to each other in order to suppress the waveguide mode coupling. However, if the waveguide mode coupling does not occur, the plurality of waveguides 129a to 129c may be arranged parallel to each other, and this does not impair the gist of the present invention.
　また、実施の形態４では、半導体レーザ素子１０７ａ～１０７ｃ、金属アンテナ１２８ａ～１２８ｃ及び受光素子１２０ａ～１２０ｃはスライダ１４１の端面に配置されるが、本発明は特にこれに限定されない。スライダ１４１の上面又はスライダ１４１の内部にこれらの素子を配置したり、ワンチップにこれらの素子を集積化して作製したりしてもよい。 In the fourth embodiment, the semiconductor laser elements 107a to 107c, the metal antennas 128a to 128c, and the light receiving elements 120a to 120c are arranged on the end face of the slider 141, but the present invention is not particularly limited to this. These elements may be arranged on the upper surface of the slider 141 or inside the slider 141, or these elements may be integrated on a single chip.
　また、実施の形態４では、光情報装置は、３つの光源（半導体レーザ素子１０７ａ～１０７ｃ）を備えているが、光情報装置は、１つの光源を備え、１つの光源からの光を導波路により３方向に分離して、金属アンテナに光を入射させてもよい。また、光情報装置は、記録又は再生用の光源とトラッキング用の光源とを１つずつ備え、トラッキング用の光源のみからの光をＹ字導波路で２方向に分離して、２つの金属アンテナに光を入射させてもよい。これらにより、本発明の主旨が損なわれるものではない。 In the fourth embodiment, the optical information device includes three light sources (semiconductor laser elements 107a to 107c). However, the optical information device includes one light source and guides light from one light source to the waveguide. The light may be incident on the metal antenna after being separated in three directions. Further, the optical information device includes one light source for recording or reproduction and one light source for tracking, and separates light from only the light source for tracking in two directions by a Y-shaped waveguide, thereby providing two metal antennas. Light may be incident on. These do not impair the gist of the present invention.
　また、実施の形態４では、スライダ１４１をディスク１０１の表面に平行な面内で回転させる回転素子として２つのピエゾ素子１４４ａ，１４４ｂを用いているが、スライダ１４１がディスク１０１の表面に平行な面内で回転する構成であれば、どのような駆動素子を用いてもよい。例えば、モータを用いて機械的に駆動する構成、静電気力又は磁力を用いて駆動する構成、熱膨張を利用して駆動する構成などが考えられる。 In the fourth embodiment, two piezo elements 144a and 144b are used as rotating elements for rotating the slider 141 in a plane parallel to the surface of the disk 101. However, the slider 141 is a surface parallel to the surface of the disk 101. Any driving element may be used as long as it is configured to rotate inside. For example, a configuration that mechanically drives using a motor, a configuration that drives using electrostatic force or magnetic force, a configuration that uses thermal expansion, and the like can be considered.
　また、実施の形態４において、図４７及び図４８に示すように、金属アンテナ１２８ａと金属アンテナ１２８ｂとのトラックに垂直な方向の距離及び金属アンテナ１２８ａと金属アンテナ１２８ｃとのトラックに垂直な方向の距離がトラッキング周期Ｔｐ以上であっても良い。 In Embodiment 4, as shown in FIGS. 47 and 48, the distance in the direction perpendicular to the track between the metal antenna 128a and the metal antenna 128b and the direction in the direction perpendicular to the track between the metal antenna 128a and the metal antenna 128c. The distance may be longer than the tracking period Tp.
　図４７は、本発明の実施の形態４において、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの別の配置例について説明するための示す図であり、図４８は、本発明の実施の形態４において、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃのさらに別の配置例について説明するための示す図である。 FIG. 47 is a diagram for explaining another arrangement example of the metal antennas 128a, 128b, and 128c in the fourth embodiment of the present invention, and FIG. 48 is a diagram illustrating the metal antenna in the fourth embodiment of the present invention. It is a figure shown for demonstrating another example of arrangement | positioning of 128a, 128b, and 128c.
　図４７に示すように、金属アンテナ１２８ａの先端位置１７１ａと金属アンテナ１２８ｂの先端位置１７１ｂとのトラックに垂直な方向の距離Ｐ及び金属アンテナ１２８ａの先端位置１７１ａと金属アンテナ１２８ｃの先端位置１７１ｃとのトラックに垂直な方向の距離Ｐは、ともにトラッキング周期Ｔｐ以上であっても良い。 As shown in FIG. 47, the distance P in the direction perpendicular to the track between the tip position 171a of the metal antenna 128a and the tip position 171b of the metal antenna 128b and the tip position 171a of the metal antenna 128a and the tip position 171c of the metal antenna 128c. Both the distances P in the direction perpendicular to the track may be equal to or longer than the tracking period Tp.
　また、図４８に示すように、金属アンテナ１２８ａの先端位置１７１ａと金属アンテナ１２８ｂの先端位置１７１ｂとのトラックに垂直な方向の距離Ｐ１が、トラッキング周期Ｔｐ以上であり、金属アンテナ１２８ａの先端位置１７１ａと金属アンテナ１２８ｃの先端位置１７１ｃとのトラックに垂直な方向の距離Ｐ２が、トラッキング周期Ｔｐより短くても良い。なお、距離Ｐ１が、トラッキング周期Ｔｐより短く、距離Ｐ２が、トラッキング周期Ｔｐ以上であっても良い。 As shown in FIG. 48, the distance P1 in the direction perpendicular to the track between the tip position 171a of the metal antenna 128a and the tip position 171b of the metal antenna 128b is equal to or longer than the tracking period Tp, and the tip position 171a of the metal antenna 128a. And the distance P2 in the direction perpendicular to the track between the tip end position 171c of the metal antenna 128c and the tracking period Tp may be shorter. The distance P1 may be shorter than the tracking period Tp, and the distance P2 may be longer than the tracking period Tp.
　また、実施の形態４では、検出信号ｔｅ１と検出信号ｔｅ２との加算値（ｔｅ１＋ｔｅ２）から、初期値ｔｅ１０と初期値ｔｅ２０との加算値（ｔｅ１０＋ｔｅ２０）を減算することにより、ヨーイング信号ＹＥ２を生成しているが、トラックからの位置ずれ又は金属アンテナ１２８ａ、１２８ｂ及び１２８ｃのトラックに垂直な方向の距離Ｐ１及びＰ２に応じて、生成したヨーイング信号ＹＥ２に適当な整数を掛けてヨーイング信号ＹＥ２の感度が常に一定になるように調節してもよい。 In the fourth embodiment, yawing is performed by subtracting the addition value (te1 0 + te2 0 ) of the initial value te1 0 and the initial value te2 0 from the addition value (te1 + te2) of the detection signal te1 and the detection signal te2. Although the signal YE2 is generated, the generated yawing signal YE2 is multiplied by an appropriate integer according to the positional deviation from the track or the distances P1 and P2 in the direction perpendicular to the track of the metal antennas 128a, 128b and 128c. The sensitivity of the signal YE2 may be adjusted so as to be always constant.
　また、実施の形態４では、検出信号ｔｅ０、ｔｅ１及びｔｅ２は、上記の式（１）～（３）のように仮定しているが、検出信号ｔｅ０、ｔｅ１及びｔｅ２が上記の式（１）～（３）のように単純な式で表されない場合は、信号処理により検出信号ｔｅ０、ｔｅ１及びｔｅ２から上記の式（１）～（３）で表される成分だけを取り出して利用したり、生成したトラッキング信号ＴＥから信号処理によりトラックからの位置ずれに対してトラッキング周期Ｔｐで変化する成分のみ取り出して利用したりしてもよい。 In the fourth embodiment, the detection signals te0, te1, and te2 are assumed as in the above equations (1) to (3), but the detection signals te0, te1, and te2 are in the above equation (1). When it is not represented by a simple expression as in (3), only the components represented by the above expressions (1) to (3) are extracted from the detection signals te0, te1 and te2 by signal processing and used. Only a component that changes in the tracking period Tp with respect to the positional deviation from the track may be extracted from the generated tracking signal TE and used.
　次に、本発明の実施の形態４におけるトラッキング方法について実施の形態４における光情報装置を用いて説明する。 Next, a tracking method according to the fourth embodiment of the present invention will be described using the optical information device according to the fourth embodiment.
　図４９は、本発明の実施の形態４におけるトラッキング方法について説明するためのフローチャートである。 FIG. 49 is a flowchart for explaining the tracking method according to the fourth embodiment of the present invention.
　図４９のフローチャートに沿って実施の形態４におけるトラッキング方法を説明する。 A tracking method according to the fourth embodiment will be described with reference to the flowchart of FIG.
　まず、第１のステップ３２１において、光源である半導体レーザ素子１０７ａ、１０７ｂ及び１０７ｃは、光を出射し、複数の共鳴素子である金属アンテナ１２８ａ、１２８ｂ及び１２８ｃに光を入射させてプラズモン共鳴を励起する。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、微粒子１０２上でプラズモン共鳴条件が満たされるように設計されている。プラズモン共鳴は、トラックからの位置ずれが大きくなるにつれて弱まる。 First, in the first step 321, the semiconductor laser elements 107a, 107b, and 107c that are light sources emit light, and light is incident on the metal antennas 128a, 128b, and 128c that are a plurality of resonance elements to excite plasmon resonance. To do. The metal antennas 128 a, 128 b, and 128 c are designed so that the plasmon resonance condition is satisfied on the fine particle 102. Plasmon resonance weakens as the positional deviation from the track increases.
　次に、第２のステップ３２２において、受光素子１１０ａ、１１０ｂ及び１１０ｃは、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの共鳴状態の変化を個別に検出し、検出信号ｔｅ０、ｔｅ１及びｔｅ２を出力する。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃは、プラズモン共鳴が励起されると、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度が低下するように設計されている。 Next, in the second step 322, the light receiving elements 110a, 110b and 110c individually detect changes in the resonance state of the metal antennas 128a, 128b and 128c, and output detection signals te0, te1 and te2. The metal antennas 128a, 128b, and 128c are designed such that the intensity of reflected light from the metal antennas 128a, 128b, and 128c decreases when plasmon resonance is excited.
　このため、金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度を受光素子１２０ａ、１２０ｂ及び１２０ｃで個別に検出することで、個々の金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの共鳴状態の変化を検出することができる。金属アンテナ１２８ａ、１２８ｂ及び１２８ｃからの反射光強度は、トラックからの距離に対して図１３（Ａ）のような変化を示し、トラック位置で最小値となり、トラック位置からトラッキング周期Ｔｐの半分だけ離れた位置で最大値となる。 Therefore, by detecting the reflected light intensity from the metal antennas 128a, 128b, and 128c individually by the light receiving elements 120a, 120b, and 120c, it is possible to detect changes in the resonance state of the individual metal antennas 128a, 128b, and 128c. it can. The reflected light intensity from the metal antennas 128a, 128b, and 128c changes as shown in FIG. 13A with respect to the distance from the track, becomes a minimum value at the track position, and is separated from the track position by half of the tracking period Tp. The maximum value at the position.
　次に、第３のステップ３２３において、モータ１４３は、スライダ１４１をトラックに垂直な方向に微少量だけ走査する。受光素子１２０ｂ及び１２０ｃは、トラックに垂直な方向の変位に応じて、検出信号ｔｅ１及びｔｅ２を出力する。 Next, in the third step 323, the motor 143 scans the slider 141 by a small amount in the direction perpendicular to the track. The light receiving elements 120b and 120c output detection signals te1 and te2 according to the displacement in the direction perpendicular to the track.
　次に、第４のステップ３２４において、位相比較回路１５２は、検出信号ｔｅ１及びｔｅ２のトラックに垂直な方向の変位量に対する位相差をヨーイング信号ＹＥ１として演算する。 Next, in the fourth step 324, the phase comparison circuit 152 calculates the phase difference with respect to the displacement amount in the direction perpendicular to the track of the detection signals te1 and te2 as the yawing signal YE1.
　次に、第５のステップ３２５において、第１の制御回路１５３は、ヨーイング信号ＹＥ１に基づいて、検出信号ｔｅ１及びｔｅ２の位相差がπラジアンとなるように、ピエゾ素子１４４ａ及び１４４ｂを制御する。ピエゾ素子１４４ａ及び１４４ｂは、スライダ１４１をディスク１０１の表面に平行な面内で回転させる。検出信号ｔｅ１及びｔｅ２は、トラックに垂直な方向の変位量に対してトラッキング周期Ｔｐで変化する。そのため、検出信号ｔｅ１及びｔｅ２の位相差がπラジアンとなるとき、金属アンテナ１２８ｂ及び１２８ｃの間のトラックに垂直な方向の距離はトラッキング周期Ｔｐの半分となる。そして、第１のサンプリングホールド回路１５４ａ及び第２のサンプリングホールド回路１５４ｂは、ヨーイング信号ＹＥ１がπラジアンとなったときの検出信号ｔｅ１及びｔｅ２の値を初期値ｔｅ１０及びｔｅ２０として記憶する。 Next, in the fifth step 325, the first control circuit 153 controls the piezo elements 144a and 144b based on the yawing signal YE1 so that the phase difference between the detection signals te1 and te2 becomes π radians. The piezoelectric elements 144 a and 144 b rotate the slider 141 in a plane parallel to the surface of the disk 101. The detection signals te1 and te2 change with the tracking period Tp with respect to the displacement amount in the direction perpendicular to the track. Therefore, when the phase difference between the detection signals te1 and te2 is π radians, the distance in the direction perpendicular to the track between the metal antennas 128b and 128c is half the tracking period Tp. Then, the first sample and hold circuit 154a and the second sample and hold circuit 154b stores a value of the detection signal te1 and te2 when yawing signal YE1 becomes π radians as an initial value te1 0 and te2 0.
　次に、第６のステップ３２６において、モータ１４３は、スライダ１４１をトラックに垂直な方向に走査する。受光素子１２０ｂ及び１２０ｃは、トラックに垂直な方向の変位に応じて、検出信号ｔｅ１及びｔｅ２を出力する。 Next, in a sixth step 326, the motor 143 scans the slider 141 in a direction perpendicular to the track. The light receiving elements 120b and 120c output detection signals te1 and te2 according to the displacement in the direction perpendicular to the track.
　次に、第７のステップ３２７において、補正値演算回路１６２は、トラックからの位置ずれが０となる位置においてトラッキング信号ＴＥがゼロクロスするような補正値ａ及びｂを演算する。このとき、補正値演算回路１６２は、上記の式（５）の関係を満たすように、補正値ａ及びｂを決定する。補正値ａが上記の式（６）を満たす場合、信号振幅が“２”となるトラッキング信号ＴＥが得られる。 Next, in a seventh step 327, the correction value calculation circuit 162 calculates correction values a and b such that the tracking signal TE crosses zero at a position where the positional deviation from the track becomes zero. At this time, the correction value calculation circuit 162 determines the correction values a and b so as to satisfy the relationship of the above formula (5). When the correction value a satisfies the above equation (6), a tracking signal TE having a signal amplitude “2” is obtained.
　次に、第８のステップ３２８において、ヨーイング信号演算回路１５１は、検出信号ｔｅ１及びｔｅ２の和の初期値ｔｅ１０及びｔｅ２０の和（ｔｅ１０＋ｔｅ２０）からの変化量をヨーイング信号ＹＥ２（ＹＥ２＝（ｔｅ１＋ｔｅ２）－（ｔｅ１０＋ｔｅ２０））として演算する。初期値ｔｅ１０及びｔｅ２０は、トラックからの位置ずれに対する位相差がπラジアンであるため、図４１に示したように、オフトラックの有無に関わらず一定値となる。このため、ヨーイング信号演算回路１５１は、オフトラック又は金属アンテナ１２８ａ、１２８ｂ及び１２８ｃの配置に関わらず、常にヨーイング信号ＹＥ２を生成することができる。 Next, in an eighth step 328, the yawing signal calculation circuit 151 calculates the amount of change from the sum (te1 0 + te2 0 ) of the initial values te1 0 and te2 0 of the sum of the detection signals te1 and te2 as the yawing signal YE2 (YE2 = (Te1 + te2) − (te1 0 + te2 0 )) The initial values te1 0 and te2 0 are constant values regardless of the presence or absence of off-track as shown in FIG. 41 because the phase difference with respect to the positional deviation from the track is π radians. Therefore, the yawing signal calculation circuit 151 can always generate the yawing signal YE2 regardless of the arrangement of the off-track or metal antennas 128a, 128b, and 128c.
　なお、具体的には、第１の加算回路１５５ａは、初期値ｔｅ１０と初期値ｔｅ２０とを加算する。第２の加算回路１５５ｂは、検出信号ｔｅ１と検出信号ｔｅ２とを加算する。差分回路１５６は、検出信号ｔｅ１と検出信号ｔｅ２との加算値（ｔｅ１＋ｔｅ２）から、初期値ｔｅ１０と初期値ｔｅ２０との加算値（ｔｅ１０＋ｔｅ２０）を減算することにより、ヨーイング信号ＹＥ２を算出する。 Specifically, the first addition circuit 155a adds the initial value te1 0 and the initial value te2 0 . The second addition circuit 155b adds the detection signal te1 and the detection signal te2. The difference circuit 156 subtracts the addition value (te1 0 + te2 0 ) of the initial value te1 0 and the initial value te2 0 from the addition value (te1 + te2) of the detection signal te1 and the detection signal te2, thereby obtaining the yawing signal YE2 calculate.
　次に、第９のステップ３２９において、第２の制御回路１５７は、ヨーイング信号ＹＥ２に基づいてピエゾ素子１４４ａ及び１４４ｂを制御する。ピエゾ素子１４４ａ及び１４４ｂは、スライダ１４１をディスク１０１の表面に平行な面内で回転させる。これにより、金属アンテナ１２８ｂ及び１２８ｃの間のトラックに垂直な方向の距離が、トラッキング周期Ｔｐの半分に保たれる。 Next, in the ninth step 329, the second control circuit 157 controls the piezo elements 144a and 144b based on the yawing signal YE2. The piezoelectric elements 144 a and 144 b rotate the slider 141 in a plane parallel to the surface of the disk 101. As a result, the distance between the metal antennas 128b and 128c in the direction perpendicular to the track is maintained at half the tracking period Tp.
　次に、第１０のステップ３３０において、第１の差分回路１６３ａは、検出信号ｔｅ１から検出信号ｔｅ０を減算し、重み付き差分回路１６４へ出力する。第２の差分回路１６３ｂは、検出信号ｔｅ２から検出信号ｔｅ０を減算し、重み付き差分回路１６４へ出力する。重み付き差分回路１６４は、補正値演算回路１６２によって算出された補正値ａを第１の差分回路１６３ａによって算出された減算値（ｔｅ１－ｔｅ０）に乗算した値から、補正値演算回路１６２によって算出された補正値ｂを第１の差分回路１６３ａによって算出された減算値（ｔｅ２－ｔｅ０）に乗算した値を減算し、トラッキング信号ＴＥ（ＴＥ＝ａ×（ｔｅ１－ｔｅ０）－ｂ×（ｔｅ２－ｔｅ０））を演算する。 Next, in the tenth step 330, the first difference circuit 163a subtracts the detection signal te0 from the detection signal te1 and outputs it to the weighted difference circuit 164. The second difference circuit 163b subtracts the detection signal te0 from the detection signal te2, and outputs the result to the weighted difference circuit 164. The weighted difference circuit 164 is calculated by the correction value calculation circuit 162 from a value obtained by multiplying the correction value a calculated by the correction value calculation circuit 162 by the subtraction value (te1-te0) calculated by the first difference circuit 163a. A value obtained by multiplying the corrected value b by the subtraction value (te2-te0) calculated by the first difference circuit 163a is subtracted, and the tracking signal TE (TE = a × (te1-te0) −b × (te2- te0)) is calculated.
　トラッキング信号ＴＥは、図４６（Ｂ）に示したように、金属アンテナ１２８ｂ及び１２８ｃの間のトラックに垂直な方向の距離に関わらず、トラック位置においてゼロクロスし、トラックからの位置ずれがトラッキング周期Ｔｐの１／４であるときに最大値又は最小値となる。補正値ａ及びｂを用いてトラッキング信号ＴＥが生成されることで、トラックに垂直な方向に任意の距離だけ離れた金属アンテナ１２８ｂ及び１２８ｃを用いてトラッキング信号ＴＥを生成することができる。 As shown in FIG. 46B, the tracking signal TE is zero-crossed at the track position regardless of the distance between the metal antennas 128b and 128c in the direction perpendicular to the track, and the positional deviation from the track is the tracking period Tp. It becomes the maximum value or the minimum value when it is 1/4. By generating the tracking signal TE using the correction values a and b, the tracking signal TE can be generated using the metal antennas 128b and 128c separated by an arbitrary distance in the direction perpendicular to the track.
　次に、第１１のステップ３３１において、モータ１４３は、トラッキング信号演算回路１６１によって演算されたトラッキング信号ＴＥに応じて、スライダ１４１をトラックに垂直な方向に移動させる。モータ１４３は、スライダ１４１をトラックに垂直な方向に移動させ、トラック位置を調節する。重み付き差分回路１６４によって演算されたトラッキング信号ＴＥは、制御回路１６５へ出力される。制御回路１６５は、トラッキング信号ＴＥに応じてモータ１４３を駆動してスライダ１４１をトラックに垂直な方向に移動させる。 Next, in an eleventh step 331, the motor 143 moves the slider 141 in a direction perpendicular to the track in accordance with the tracking signal TE calculated by the tracking signal calculation circuit 161. The motor 143 moves the slider 141 in a direction perpendicular to the track to adjust the track position. The tracking signal TE calculated by the weighted difference circuit 164 is output to the control circuit 165. The control circuit 165 drives the motor 143 according to the tracking signal TE to move the slider 141 in a direction perpendicular to the track.
　上記第８のステップ３２８乃至第１１のステップ３３１の処理が繰り返されることにより、記録又は再生用の金属アンテナ１２８ａを微粒子１０２に対して常に安定かつ高精度にトラッキングさせることができる。 By repeating the processes of the eighth step 328 to the eleventh step 331, the recording or reproducing metal antenna 128a can be constantly and accurately tracked with respect to the fine particles 102.
　なお、本実施の形態４では、受光素子１２０ａ、１２０ｂ及び１２０ｃからの検出信号ｔｅ０、ｔｅ１及びｔｅ２に基づいてトラッキング信号ＴＥ及びヨーイング信号ＹＥ１及びＹＥ２が生成されるが、検出信号ｔｅ０、ｔｅ１及びｔｅ２の高周波成分をローパスフィルタにより除去してもよく、また、トラッキング信号ＴＥ、ヨーイング信号ＹＥ１及びＹＥ２の高周波成分をローパスフィルタにより除去してもよい。 In the fourth embodiment, the tracking signal TE and the yawing signals YE1 and YE2 are generated based on the detection signals te0, te1 and te2 from the light receiving elements 120a, 120b and 120c, but the detection signals te0, te1 and te2 May be removed by a low-pass filter, and high-frequency components of the tracking signal TE and yawing signals YE1 and YE2 may be removed by a low-pass filter.
　以上のように、実施の形態４のトラッキング方法は、保持素子をトラックに垂直な方向に走査する走査ステップと、複数の共鳴素子の各々の共鳴状態の変化を個別に検出し、複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力する検出ステップと、複数の検出信号のトラックに垂直な方向の変位量に対する位相差がπラジアンとなるように保持素子を情報記録媒体の表面に平行な面内で回転させる回転ステップと、を包含する。このため、複数の共鳴素子のトラックに垂直な方向の距離をトラッキング周期Ｔｐの半分に調節することができる。 As described above, in the tracking method according to the fourth embodiment, the scanning step of scanning the holding element in the direction perpendicular to the track, the change in the resonance state of each of the plurality of resonance elements is individually detected, and the plurality of resonance elements A detecting step for outputting a plurality of detection signals representing changes in the respective resonance states of the plurality of detection signals; A rotating step of rotating in a plane parallel to the surface. For this reason, the distance in the direction perpendicular to the tracks of the plurality of resonance elements can be adjusted to half the tracking period Tp.
　また、実施の形態４のトラッキング方法は、複数の検出信号の和からヨーイング信号を演算するヨーイング信号演算ステップと、ヨーイング信号に応じて保持素子を情報記録媒体の表面に平行な面内で回転させる回転ステップと、を包含する。このため、情報記録媒体の偏心又はモータ１４３による保持素子の移動によって起こるトラック角度変化を補正することができ、複数の共鳴素子のトラックに垂直な方向の距離を常にトラッキング周期Ｔｐの半分に保つことができる。 The tracking method according to the fourth embodiment includes a yawing signal calculation step for calculating a yawing signal from the sum of a plurality of detection signals, and a holding element is rotated in a plane parallel to the surface of the information recording medium according to the yawing signal. A rotation step. For this reason, it is possible to correct the track angle change caused by the eccentricity of the information recording medium or the movement of the holding element by the motor 143, and always keep the distance in the direction perpendicular to the track of the plurality of resonance elements at half the tracking period Tp. Can do.
　また、実施の形態４のトラッキング方法は、複数の検出信号から補正値を演算する補正値演算ステップと、複数の検出信号のそれぞれと補正値との積の差をトラッキング信号として演算するトラッキング信号演算ステップと、を包含する。これにより、任意の距離を隔てて配置された複数の共鳴素子を用いて、安定にトラッキング信号を生成することができる。 In addition, the tracking method according to the fourth embodiment includes a correction value calculation step for calculating a correction value from a plurality of detection signals, and a tracking signal calculation for calculating a difference between the products of the plurality of detection signals and the correction value as a tracking signal. Steps. Thereby, a tracking signal can be stably generated using a plurality of resonant elements arranged at an arbitrary distance.
　なお、上述した具体的実施形態には以下の構成を有する発明が主に含まれている。 The specific embodiments described above mainly include inventions having the following configurations.
　本発明の一局面に係る光情報装置は、トラックを有する情報記録媒体に情報を記録又は再生する光情報装置であって、光源と、前記光源からの光が入射し、前記情報記録媒体と相互作用し、前記トラックからの距離に応じて共鳴状態が変化する複数の共鳴素子と、前記複数の共鳴素子の位置を前記トラックに垂直な方向にずらして配置し、かつ前記複数の共鳴素子間の距離を一定に固定して保持する保持素子と、前記複数の共鳴素子の各々の共鳴状態の変化を個別に検出する第１の検出素子と、前記第１の検出素子によって検出された前記共鳴状態の変化に基づいてトラッキング信号を演算するトラッキング信号演算回路と、前記トラッキング信号演算回路によって演算された前記トラッキング信号に応じて前記保持素子を前記トラックに垂直な方向に移動させる第１の移動素子と、を備える。 An optical information device according to one aspect of the present invention is an optical information device for recording or reproducing information on an information recording medium having a track, and a light source, light from the light source is incident thereon, and the information recording medium is mutually connected. A plurality of resonant elements that change the resonance state according to the distance from the track, and the positions of the plurality of resonant elements are shifted in a direction perpendicular to the track, and between the plurality of resonant elements A holding element that holds the distance fixed, a first detection element that individually detects a change in the resonance state of each of the plurality of resonance elements, and the resonance state that is detected by the first detection element A tracking signal calculation circuit for calculating a tracking signal based on the change of the tracking signal, and the holding element in the track according to the tracking signal calculated by the tracking signal calculation circuit Comprising a first moving element that moves in a straight direction, the.
　この構成によれば、複数の共鳴素子は、光源からの光が入射し、情報記録媒体と相互作用し、トラックからの距離に応じて共鳴状態が変化する。保持素子は、複数の共鳴素子の位置をトラックに垂直な方向にずらして配置し、かつ複数の共鳴素子間の距離を一定に固定して保持する。第１の検出素子は、複数の共鳴素子の各々の共鳴状態の変化を個別に検出する。トラッキング信号演算回路は、第１の検出素子によって検出された共鳴状態の変化に基づいてトラッキング信号を演算する。第１の移動素子は、トラッキング信号演算回路によって演算されたトラッキング信号に応じて保持素子をトラックに垂直な方向に移動させる。 According to this configuration, light from the light source enters the plurality of resonance elements, interacts with the information recording medium, and the resonance state changes according to the distance from the track. The holding element is arranged by shifting the position of the plurality of resonance elements in a direction perpendicular to the track, and holds the distance between the plurality of resonance elements fixed at a constant value. The first detection element individually detects a change in the resonance state of each of the plurality of resonance elements. The tracking signal calculation circuit calculates a tracking signal based on a change in the resonance state detected by the first detection element. The first moving element moves the holding element in a direction perpendicular to the track in accordance with the tracking signal calculated by the tracking signal calculation circuit.
　したがって、複数の共鳴素子の位置がトラックに垂直な方向にずらして配置され、かつ複数の共鳴素子間の距離が一定に固定されて保持されるので、情報記録媒体との相互作用により複数の共鳴素子とトラックとの相対的な位置が変化することがない。そのため、トラック位置からの変位にのみ依存した安定かつ高精度なトラッキングを行うことができる。 Accordingly, the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is fixed and held constant. The relative position between the element and the track does not change. Therefore, stable and highly accurate tracking that depends only on the displacement from the track position can be performed.
　また、複数の共鳴素子の各々の共鳴状態の変化が個別に検出され、検出された共鳴状態の変化に基づいてトラッキング信号が演算されるので、検出信号が複数の共鳴素子の周辺の光学定数の変化に敏感に反応し、トラックからの微小な位置ずれに対して変調度の高いトラッキング信号が得られる。そのため、安定かつ高精度なトラッキングを行うことができる。 In addition, since a change in the resonance state of each of the plurality of resonance elements is individually detected and a tracking signal is calculated based on the detected change in the resonance state, the detection signal has an optical constant around the plurality of resonance elements. A tracking signal having a high degree of modulation can be obtained with respect to a minute positional deviation from the track, which reacts sensitively to changes. Therefore, stable and highly accurate tracking can be performed.
　また、上記の光情報装置において、前記複数の共鳴素子を前記情報記録媒体の表面に垂直な方向に移動させる第２の移動素子をさらに備え、前記第２の移動素子は、前記保持素子と前記情報記録媒体との間を流れる気流の力により、前記情報記録媒体と前記保持素子との間の距離を一定に保持することが好ましい。 The optical information apparatus may further include a second moving element that moves the plurality of resonant elements in a direction perpendicular to a surface of the information recording medium, and the second moving element includes the holding element and the holding element. It is preferable that the distance between the information recording medium and the holding element is kept constant by the force of the airflow flowing between the information recording medium.
　この構成によれば、第２の移動素子は、複数の共鳴素子を情報記録媒体の表面に垂直な方向に移動させる。第２の移動素子は、保持素子と情報記録媒体との間を流れる気流の力により、情報記録媒体と保持素子との間の距離を、一定に保持する。 According to this configuration, the second moving element moves the plurality of resonant elements in a direction perpendicular to the surface of the information recording medium. The second moving element keeps the distance between the information recording medium and the holding element constant by the force of the airflow flowing between the holding element and the information recording medium.
　したがって、保持素子と情報記録媒体との間を流れる気流の力により、情報記録媒体と保持素子との間の距離は、一定に保持されるので、簡易な構成により、複数の共鳴素子と情報記録媒体との間の距離を一定に保持することができる。 Accordingly, since the distance between the information recording medium and the holding element is kept constant by the force of the airflow flowing between the holding element and the information recording medium, a plurality of resonance elements and the information recording medium can be recorded with a simple configuration. The distance to the medium can be kept constant.
　また、上記の光情報装置において、前記複数の共鳴素子を前記情報記録媒体の表面に垂直な方向に移動させる第２の移動素子をさらに備え、前記第２の移動素子は、前記保持素子と前記情報記録媒体とを接触させることが好ましい。 The optical information apparatus may further include a second moving element that moves the plurality of resonant elements in a direction perpendicular to a surface of the information recording medium, and the second moving element includes the holding element and the holding element. It is preferable to contact the information recording medium.
　この構成によれば、第２の移動素子は、複数の共鳴素子を情報記録媒体の表面に垂直な方向に移動させる。第２の移動素子は、保持素子と情報記録媒体とを接触させる。したがって、複数の共鳴素子と情報記録媒体との間の距離を容易に制御することができる。 According to this configuration, the second moving element moves the plurality of resonant elements in a direction perpendicular to the surface of the information recording medium. The second moving element brings the holding element and the information recording medium into contact with each other. Therefore, the distance between the plurality of resonance elements and the information recording medium can be easily controlled.
　また、上記の光情報装置において、前記複数の共鳴素子と前記情報記録媒体との距離を検出する第２の検出素子と、前記第２の検出素子からの検出信号に応じて、前記複数の共鳴素子と前記情報記録媒体との間の距離が一定になるように、前記複数の共鳴素子を前記情報記録媒体の表面に垂直な方向に移動させる第２の移動素子とをさらに備えることが好ましい。 In the optical information device, the plurality of resonance elements may be detected in accordance with a second detection element that detects a distance between the plurality of resonance elements and the information recording medium, and a detection signal from the second detection element. It is preferable to further include a second moving element that moves the plurality of resonant elements in a direction perpendicular to the surface of the information recording medium so that the distance between the element and the information recording medium is constant.
　この構成によれば、第２の検出素子は、複数の共鳴素子と情報記録媒体との距離を検出する。第２の移動素子は、第２の検出素子からの検出信号に応じて、複数の共鳴素子と情報記録媒体との間の距離が一定になるように、複数の共鳴素子を情報記録媒体の表面に垂直な方向に移動させる。 According to this configuration, the second detection element detects the distance between the plurality of resonance elements and the information recording medium. The second moving element has a plurality of resonant elements placed on the surface of the information recording medium such that distances between the plurality of resonant elements and the information recording medium are constant according to a detection signal from the second detecting element. Move in a direction perpendicular to.
　したがって、複数の共鳴素子と情報記録媒体との距離が検出されるので、複数の共鳴素子と情報記録媒体との間の距離をより高精度に制御することができる。 Therefore, since the distance between the plurality of resonance elements and the information recording medium is detected, the distance between the plurality of resonance elements and the information recording medium can be controlled with higher accuracy.
　また、上記の光情報装置において、前記第１の検出素子は、複数の受光素子を含み、前記光情報装置は、前記複数の共鳴素子からの光を前記複数の受光素子に導く複数の導波路をさらに備えることが好ましい。 In the above optical information device, the first detection element includes a plurality of light receiving elements, and the optical information device includes a plurality of waveguides that guide light from the plurality of resonance elements to the plurality of light receiving elements. It is preferable to further comprise.
　この構成によれば、第１の検出素子は、複数の受光素子を含む。そして、複数の導波路は、複数の共鳴素子からの光を複数の受光素子に導く。したがって、複数の共鳴素子の各々の共鳴状態の変化を確実に検出することができる。 According to this configuration, the first detection element includes a plurality of light receiving elements. The plurality of waveguides guide light from the plurality of resonance elements to the plurality of light receiving elements. Therefore, it is possible to reliably detect a change in the resonance state of each of the plurality of resonance elements.
　また、上記の光情報装置において、前記光源は、それぞれ波長の異なる光を出射する複数の光源を含み、前記複数の共鳴素子は、前記複数の光源のそれぞれから出射された光の周波数を共鳴周波数とする形状又は材質で形成され、前記第１の検出素子は、複数の受光素子を含み、前記光情報装置は、前記複数の共鳴素子からの周波数の異なる複数の光を分離して、前記複数の光のそれぞれを対応する前記複数の受光素子に導く光学素子をさらに備えることが好ましい。 Further, in the above optical information device, the light source includes a plurality of light sources that emit light having different wavelengths, and the plurality of resonance elements determine a frequency of light emitted from each of the plurality of light sources as a resonance frequency. The first detection element includes a plurality of light receiving elements, and the optical information device separates the plurality of lights having different frequencies from the plurality of resonance elements, and It is preferable to further include an optical element that guides each of the light beams to the corresponding light receiving elements.
　この構成によれば、光源は、それぞれ波長の異なる光を出射する複数の光源を含む。複数の共鳴素子は、複数の光源のそれぞれから出射された光の周波数を共鳴周波数とする形状又は材質で形成される。第１の検出素子は、複数の受光素子を含む。光学素子は、複数の共鳴素子からの周波数の異なる複数の光を分離して、複数の光のそれぞれを対応する複数の受光素子に導く。 According to this configuration, the light source includes a plurality of light sources that emit light having different wavelengths. The plurality of resonance elements are formed in a shape or material having a resonance frequency that is the frequency of light emitted from each of the plurality of light sources. The first detection element includes a plurality of light receiving elements. The optical element separates a plurality of lights having different frequencies from the plurality of resonance elements, and guides each of the plurality of lights to a corresponding plurality of light receiving elements.
　したがって、波長の違いを利用して複数の共鳴素子の個々の共鳴状態が検出されるので、光源、第１の検出素子及び複数の共鳴素子を微小領域に集積化する必要がなく、光情報装置を容易に作製することができる。 Accordingly, since the individual resonance states of the plurality of resonance elements are detected using the difference in wavelength, it is not necessary to integrate the light source, the first detection element, and the plurality of resonance elements in a minute region, and the optical information device Can be easily manufactured.
　また、上記の光情報装置において、前記第１の検出素子は、前記複数の共鳴素子から発生する近接場光を検出可能な範囲に配置された複数の受光素子を含むことが好ましい。 In the above optical information device, it is preferable that the first detection element includes a plurality of light receiving elements arranged in a range in which near-field light generated from the plurality of resonance elements can be detected.
　この構成によれば、複数の受光素子は、複数の共鳴素子から発生する近接場光を検出可能な範囲に配置されるので、複数の共鳴素子から発生する近接場光を個別に検出することができ、高精度で高効率なトラッキング信号を得ることができる。 According to this configuration, the plurality of light receiving elements are arranged in a range in which the near field light generated from the plurality of resonance elements can be detected, so that the near field light generated from the plurality of resonance elements can be individually detected. And a highly accurate and highly efficient tracking signal can be obtained.
　また、上記の光情報装置において、前記トラックは、列状に配置された微粒子により規定されることが好ましい。この構成によれば、列状に配置された微粒子に対して、安定かつ高精度なトラッキングを行うことができる。 In the above optical information device, the track is preferably defined by fine particles arranged in a line. According to this configuration, stable and highly accurate tracking can be performed on the fine particles arranged in a row.
　また、上記の光情報装置において、前記トラックは、グルーブにより規定されることが好ましい。この構成によれば、グルーブに対して、安定かつ高精度なトラッキングを行うことができる。 In the above optical information device, the track is preferably defined by a groove. According to this configuration, stable and highly accurate tracking can be performed on the groove.
　また、上記の光情報装置において、前記複数の共鳴素子間の前記トラックに垂直な方向の距離は、トラックピッチの半分であることが好ましい。 In the above optical information device, it is preferable that the distance between the plurality of resonant elements in the direction perpendicular to the track is half of the track pitch.
　この構成によれば、トラッキング信号は、トラックからの位置ずれがトラックピッチの４分の１となる位置で最大又は最小となり、トラックからの位置ずれがトラックピッチの半分となる位置で０となるので、トラックからの位置ずれを容易に検出することができる。 According to this configuration, the tracking signal is maximum or minimum at a position where the positional deviation from the track is a quarter of the track pitch, and becomes zero at a position where the positional deviation from the track is half the track pitch. The positional deviation from the track can be easily detected.
　また、上記の光情報装置において、前記光源から前記複数の共鳴素子に入射する入射光の偏光方向は、前記情報記録媒体の表面に垂直な方向であることが好ましい。 In the above optical information device, it is preferable that the polarization direction of incident light incident on the plurality of resonance elements from the light source is a direction perpendicular to the surface of the information recording medium.
　この構成によれば、複数の共鳴素子を情報記録媒体の表面に対して垂直に保持し、情報記録媒体の表面に対して平行な面内に光源及び複数の共鳴素子を配置することができるので、情報記録媒体の表面に垂直な方向の光学装置の大きさを小さくすることができる。 According to this configuration, the plurality of resonance elements can be held perpendicular to the surface of the information recording medium, and the light source and the plurality of resonance elements can be arranged in a plane parallel to the surface of the information recording medium. The size of the optical device in the direction perpendicular to the surface of the information recording medium can be reduced.
　また、上記の光情報装置において、前記光源から前記複数の共鳴素子に入射する入射光の偏光方向は、前記情報記録媒体の表面に対して平行な方向であることが好ましい。この構成によれば、複数の共鳴素子を情報記録媒体の表面に対して垂直に保持する必要がないので、保持素子を容易に作製することができる。 In the above optical information device, it is preferable that the polarization direction of incident light incident on the plurality of resonant elements from the light source is a direction parallel to the surface of the information recording medium. According to this configuration, it is not necessary to hold the plurality of resonance elements perpendicular to the surface of the information recording medium, and thus the holding element can be easily manufactured.
　また、上記の光情報装置において、前記保持素子は、前記複数の共鳴素子の位置を前記トラックの長手方向にずらして配置することが好ましい。 In the optical information device, it is preferable that the holding element is arranged by shifting the positions of the plurality of resonance elements in the longitudinal direction of the track.
　この構成によれば、複数の共鳴素子の位置がトラックの長手方向にずらして配置されるので、複数の共鳴素子間での相互作用を抑制することができ、複数の共鳴素子の形状の自由度を高くすることができる。 According to this configuration, since the positions of the plurality of resonance elements are shifted in the longitudinal direction of the track, the interaction between the plurality of resonance elements can be suppressed, and the degree of freedom in the shape of the plurality of resonance elements Can be high.
　また、上記の光情報装置において、前記複数の共鳴素子間の前記トラックの長手方向の位置は、前記複数の共鳴素子のうちの１つの共鳴素子の前記トラックの長手方向の厚さ以上にずれていることが好ましい。 In the above optical information device, the position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the thickness in the longitudinal direction of the track of one resonance element of the plurality of resonance elements. Preferably it is.
　この構成によれば、複数の共鳴素子間のトラックの長手方向の位置は、複数の共鳴素子のうちの１つの共鳴素子のトラックの長手方向の厚さ以上にずれているので、複数の共鳴素子間での相互作用をより抑制することができる。 According to this configuration, the position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the thickness in the longitudinal direction of the track of one resonance element among the plurality of resonance elements. The interaction between them can be further suppressed.
　また、上記の光情報装置において、前記光源から前記複数の共鳴素子に入射する入射光の偏光方向は、前記情報記録媒体の表面に対して平行な方向かつ前記トラックに対して平行な方向であり、前記複数の共鳴素子間の前記トラックの長手方向の位置は、前記複数の共鳴素子のうちの１つの共鳴素子の前記トラックの長手方向の長さ以上にずれていることが好ましい。 In the optical information device, the polarization direction of incident light incident on the plurality of resonance elements from the light source is a direction parallel to the surface of the information recording medium and a direction parallel to the track. Preferably, the position in the longitudinal direction of the track between the plurality of resonance elements is shifted more than the length in the longitudinal direction of the track of one resonance element of the plurality of resonance elements.
　この構成によれば、光源から複数の共鳴素子に入射する入射光の偏光方向は、情報記録媒体の表面に対して平行な方向かつトラックに対して平行な方向である。複数の共鳴素子間のトラックの長手方向の位置は、複数の共鳴素子のうちの１つの共鳴素子のトラックの長手方向の長さ以上にずれている。したがって、複数の共鳴素子間のトラックの長手方向の位置は、複数の共鳴素子のうちの１つの共鳴素子のトラックの長手方向の長さ以上にずれているので、複数の共鳴素子間での相互作用をより抑制することができる。 According to this configuration, the polarization direction of the incident light incident on the plurality of resonance elements from the light source is parallel to the surface of the information recording medium and parallel to the track. The position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the length in the longitudinal direction of the track of one resonance element of the plurality of resonance elements. Therefore, the position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the length in the longitudinal direction of the track of one resonance element among the plurality of resonance elements. The action can be further suppressed.
　また、上記の光情報装置において、前記第１の検出素子によって検出された前記共鳴状態の変化に基づいて、前記情報記録媒体の表面に平行な面内における前記保持素子の傾きを表すヨーイング信号を演算するヨーイング信号演算回路と、前記ヨーイング信号演算回路によって演算された前記ヨーイング信号に応じて前記保持素子を前記情報記録媒体の表面に平行な面内で回転させる回転素子とをさらに備えることが好ましい。 Further, in the optical information device, a yawing signal representing an inclination of the holding element in a plane parallel to the surface of the information recording medium based on a change in the resonance state detected by the first detection element. It is preferable to further include a yawing signal calculation circuit for calculating, and a rotation element for rotating the holding element in a plane parallel to the surface of the information recording medium according to the yawing signal calculated by the yawing signal calculation circuit. .
　この構成によれば、ヨーイング信号演算回路は、第１の検出素子によって検出された共鳴状態の変化に基づいて、情報記録媒体の表面に平行な面内における保持素子の傾きを表すヨーイング信号を演算する。回転素子は、ヨーイング信号演算回路によって演算されたヨーイング信号に応じて保持素子を情報記録媒体の表面に平行な面内で回転させる。 According to this configuration, the yawing signal calculation circuit calculates a yawing signal that represents the inclination of the holding element in a plane parallel to the surface of the information recording medium, based on the change in the resonance state detected by the first detection element. To do. The rotating element rotates the holding element in a plane parallel to the surface of the information recording medium in accordance with the yawing signal calculated by the yawing signal calculation circuit.
　したがって、情報記録媒体の偏心又は保持素子をトラックに垂直な方向へ移動させることによって発生するトラックの傾きに対して、複数の共鳴素子のトラックに垂直な方向の距離が一定に保持される。したがって、安定したトラッキングを行うことができる。 Therefore, the distance in the direction perpendicular to the tracks of the plurality of resonance elements is kept constant against the eccentricity of the information recording medium or the inclination of the track generated by moving the holding element in the direction perpendicular to the track. Therefore, stable tracking can be performed.
　また、上記の光情報装置において、前記第１の検出素子は、前記複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力し、前記ヨーイング信号演算回路は、前記複数の検出信号の前記トラックに垂直な方向の変位量に対する位相差を演算し、前記回転素子は、前記位相差がπラジアンとなるように前記保持素子を前記情報記録媒体の表面に平行な面内で回転させることが好ましい。 In the optical information device, the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements, and the yawing signal calculation circuit includes the plurality of detection signals. The phase difference with respect to the displacement amount of the signal in the direction perpendicular to the track is calculated, and the rotating element rotates the holding element in a plane parallel to the surface of the information recording medium so that the phase difference becomes π radians. It is preferable to make it.
　この構成によれば、第１の検出素子は、複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力する。ヨーイング信号演算回路は、複数の検出信号のトラックに垂直な方向の変位量に対する位相差を演算する。回転素子は、位相差がπラジアンとなるように保持素子を情報記録媒体の表面に平行な面内で回転させる。 According to this configuration, the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements. The yawing signal calculation circuit calculates a phase difference with respect to a displacement amount in a direction perpendicular to the track of the plurality of detection signals. The rotating element rotates the holding element in a plane parallel to the surface of the information recording medium so that the phase difference is π radians.
　したがって、複数の検出信号のトラックに垂直な方向の変位量に対する位相差がπラジアンとなる場合、複数の検出信号のトラックに垂直な方向の距離は、トラックピッチの半分となるので、トラックからの位置ずれを容易に検出することができる。 Therefore, when the phase difference with respect to the displacement amount in the direction perpendicular to the track of the plurality of detection signals is π radians, the distance in the direction perpendicular to the track of the plurality of detection signals is half the track pitch. Misalignment can be easily detected.
　また、上記の光情報装置において、前記第１の検出素子は、前記複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力し、前記トラッキング信号演算回路は、前記第１の検出素子によって出力された前記複数の検出信号の差を前記トラッキング信号として演算することが好ましい。 In the optical information device, the first detection element outputs a plurality of detection signals representing changes in the resonance states of the plurality of resonance elements, and the tracking signal calculation circuit includes the first detection element. It is preferable to calculate a difference between the plurality of detection signals output by the detection element as the tracking signal.
　この構成によれば、第１の検出素子は、複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力する。トラッキング信号演算回路は、第１の検出素子によって出力された複数の検出信号の差をトラッキング信号として演算する。 According to this configuration, the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements. The tracking signal calculation circuit calculates a difference between a plurality of detection signals output by the first detection element as a tracking signal.
　したがって、複数の検出信号の差がトラッキング信号として演算されるので、簡単な構成により、トラッキング信号を生成することができる。 Therefore, since a difference between a plurality of detection signals is calculated as a tracking signal, the tracking signal can be generated with a simple configuration.
　また、上記の光情報装置において、前記第１の検出素子は、前記複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力し、前記トラッキング信号演算回路は、前記複数の検出信号に基づいて、前記複数の共鳴素子の前記トラックからの位置ずれを補正するための補正値を演算し、演算した前記補正値に基づいて補正した前記複数の検出信号の差を前記トラッキング信号として演算することが好ましい。 In the optical information device, the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements, and the tracking signal calculation circuit includes the plurality of detection signals. Based on the signal, a correction value for correcting the positional deviation of the plurality of resonance elements from the track is calculated, and a difference between the plurality of detection signals corrected based on the calculated correction value is used as the tracking signal. It is preferable to calculate.
　この構成によれば、第１の検出素子は、複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力する。トラッキング信号演算回路は、複数の検出信号に基づいて、複数の共鳴素子のトラックからの位置ずれを補正するための補正値を演算し、演算した補正値に基づいて補正した複数の検出信号の差をトラッキング信号として演算する。 According to this configuration, the first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements. The tracking signal calculation circuit calculates a correction value for correcting the positional deviation from the track of the plurality of resonance elements based on the plurality of detection signals, and the difference between the plurality of detection signals corrected based on the calculated correction value. Is calculated as a tracking signal.
　したがって、複数の共鳴素子のうちの一の共鳴素子とトラックの中心との間の距離と、複数の共鳴素子のうちの他の共鳴素子とトラックの中心との間の距離とが異なる場合であっても、複数の共鳴素子のトラックからの位置ずれが補正されるので、正確なトラッキング信号を生成することができる。 Therefore, the distance between one of the plurality of resonance elements and the center of the track is different from the distance between the other resonance element of the plurality of resonance elements and the center of the track. However, since the positional deviation from the track of the plurality of resonance elements is corrected, an accurate tracking signal can be generated.
　本発明の他の局面に係るトラッキング方法は、トラックを有する情報記録媒体に情報を記録又は再生する光情報装置におけるトラッキング方法であって、前記情報記録媒体と相互作用し、前記トラックからの距離に応じて共鳴状態が変化する複数の共鳴素子に光源からの光を入射させる光入射ステップと、前記複数の共鳴素子の各々の共鳴状態の変化を個別に検出する検出ステップと、前記検出ステップにおいて検出された前記共鳴状態の変化に基づいてトラッキング信号を演算するトラッキング信号演算ステップと、前記トラッキング信号演算ステップにおいて演算された前記トラッキング信号に応じて、前記複数の共鳴素子の位置を前記トラックに垂直な方向にずらして配置し、かつ前記複数の共鳴素子間の距離を一定に固定して保持する保持素子をトラックに垂直な方向に移動させる移動ステップと、を包含する。 A tracking method according to another aspect of the present invention is a tracking method in an optical information apparatus that records or reproduces information on an information recording medium having a track, and interacts with the information recording medium, at a distance from the track. A light incident step for causing light from a light source to enter a plurality of resonance elements whose resonance states change in response, a detection step for individually detecting a change in the resonance state of each of the plurality of resonance elements, and detection in the detection step A tracking signal calculation step for calculating a tracking signal based on the change in the resonance state, and positions of the plurality of resonance elements perpendicular to the track according to the tracking signal calculated in the tracking signal calculation step. Displaced in the direction, and the distance between the plurality of resonance elements is fixed and held constant Comprising a moving step, the moving the retaining element in a direction perpendicular to the track that.
　この構成によれば、光入射ステップにおいて、記録媒体と相互作用し、トラックからの距離に応じて共鳴状態が変化する複数の共鳴素子に光源からの光が入射される。検出ステップにおいて、複数の共鳴素子の各々の共鳴状態の変化が個別に検出される。トラッキング信号演算ステップにおいて、検出ステップで検出された共鳴状態の変化に基づいてトラッキング信号が演算される。移動ステップにおいて、トラッキング信号演算ステップで演算されたトラッキング信号に応じて、複数の共鳴素子の位置をトラックに垂直な方向にずらして配置し、かつ複数の共鳴素子間の距離を一定に固定して保持する保持素子がトラックに垂直な方向に移動される。 According to this configuration, in the light incident step, light from the light source is incident on the plurality of resonance elements that interact with the recording medium and change the resonance state according to the distance from the track. In the detection step, a change in the resonance state of each of the plurality of resonance elements is individually detected. In the tracking signal calculation step, the tracking signal is calculated based on the change in the resonance state detected in the detection step. In the movement step, according to the tracking signal calculated in the tracking signal calculation step, the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is fixed to be constant. The holding element to be held is moved in a direction perpendicular to the track.
　したがって、複数の共鳴素子の位置がトラックに垂直な方向にずらして配置され、かつ複数の共鳴素子間の距離が一定に固定されて保持されるので、情報記録媒体との相互作用により複数の共鳴素子とトラックとの相対的な位置が変化することがない。そのため、トラック位置からの変位にのみ依存した安定かつ高精度なトラッキングを行うことができる。 Accordingly, the positions of the plurality of resonance elements are shifted in the direction perpendicular to the track, and the distance between the plurality of resonance elements is fixed and held constant. The relative position between the element and the track does not change. Therefore, stable and highly accurate tracking that depends only on the displacement from the track position can be performed.
　また、複数の共鳴素子の各々の共鳴状態の変化が個別に検出され、検出された共鳴状態の変化に基づいてトラッキング信号が演算されるので、検出信号が複数の共鳴素子の周辺の光学定数の変化に敏感に反応し、トラックからの微小な位置ずれに対して変調度の高いトラッキング信号が得られる。そのため、安定かつ高精度なトラッキングを行うことができる。 In addition, since a change in the resonance state of each of the plurality of resonance elements is individually detected and a tracking signal is calculated based on the detected change in the resonance state, the detection signal has an optical constant around the plurality of resonance elements. A tracking signal having a high degree of modulation can be obtained with respect to a minute positional deviation from the track, which reacts sensitively to changes. Therefore, stable and highly accurate tracking can be performed.
　なお、発明を実施するための形態の項においてなされた具体的な実施態様または実施例は、あくまでも、本発明の技術内容を明らかにするものであって、そのような具体例にのみ限定して狭義に解釈されるべきものではなく、本発明の精神と特許請求事項との範囲内で、種々変更して実施することができるものである。 It should be noted that the specific embodiments or examples made in the section for carrying out the invention are merely to clarify the technical contents of the present invention, and are limited to such specific examples. The present invention should not be interpreted in a narrow sense, and various modifications can be made within the spirit and scope of the present invention.
　本発明に係る光情報装置及びトラッキング方法は、回折限界を超えて高密度に情報を記録又は再生する光情報装置において、高精度にトラッキング制御を行うことが可能になり、高密度かつ大容量の光情報装置の実現に有用である。こうした高密度かつ大容量の光情報装置は、光ディスクプレーヤ、光ディスクレコーダ、コンピュータ及びデータサーバなど多くの用途に応用できる。 The optical information device and the tracking method according to the present invention enable high-precision tracking control in an optical information device that records or reproduces information at a high density exceeding the diffraction limit. This is useful for realizing an optical information device. Such a high-density and large-capacity optical information device can be applied to many uses such as an optical disc player, an optical disc recorder, a computer, and a data server.

Claims (20)

  1. 　トラックを有する情報記録媒体に情報を記録又は再生する光情報装置であって、
    　光源と、
    　前記光源からの光が入射し、前記情報記録媒体と相互作用し、前記トラックからの距離に応じて共鳴状態が変化する複数の共鳴素子と、
    　前記複数の共鳴素子の位置を前記トラックに垂直な方向にずらして配置し、かつ前記複数の共鳴素子間の距離を一定に固定して保持する保持素子と、
    　前記複数の共鳴素子の各々の共鳴状態の変化を個別に検出する第１の検出素子と、
    　前記第１の検出素子によって検出された前記共鳴状態の変化に基づいてトラッキング信号を演算するトラッキング信号演算回路と、
    　前記トラッキング信号演算回路によって演算された前記トラッキング信号に応じて前記保持素子を前記トラックに垂直な方向に移動させる第１の移動素子と、
    を備えることを特徴とする光情報装置。     An optical information device for recording or reproducing information on an information recording medium having a track,
    A light source;
    A plurality of resonance elements that receive light from the light source, interact with the information recording medium, and change a resonance state according to a distance from the track;
    A holding element that displaces the positions of the plurality of resonance elements in a direction perpendicular to the track, and holds a fixed distance between the plurality of resonance elements; and
    A first detection element for individually detecting a change in resonance state of each of the plurality of resonance elements;
    A tracking signal calculation circuit that calculates a tracking signal based on a change in the resonance state detected by the first detection element;
    A first moving element that moves the holding element in a direction perpendicular to the track according to the tracking signal calculated by the tracking signal calculation circuit;
    An optical information device comprising:
  2. 　前記複数の共鳴素子を前記情報記録媒体の表面に垂直な方向に移動させる第２の移動素子をさらに備え、
    　前記第２の移動素子は、前記保持素子と前記情報記録媒体との間を流れる気流の力により、前記情報記録媒体と前記保持素子との間の距離を一定に保持することを特徴とする請求項１に記載の光情報装置。     A second moving element for moving the plurality of resonant elements in a direction perpendicular to the surface of the information recording medium;
    The second moving element is configured to maintain a constant distance between the information recording medium and the holding element by a force of an airflow flowing between the holding element and the information recording medium. Item 4. The optical information device according to Item 1.
  3. 　前記複数の共鳴素子を前記情報記録媒体の表面に垂直な方向に移動させる第２の移動素子をさらに備え、
    　前記第２の移動素子は、前記保持素子と前記情報記録媒体とを接触させることを特徴とする請求項１に記載の光情報装置。     A second moving element for moving the plurality of resonant elements in a direction perpendicular to the surface of the information recording medium;
    The optical information apparatus according to claim 1, wherein the second moving element brings the holding element and the information recording medium into contact with each other.
  4. 　前記複数の共鳴素子と前記情報記録媒体との距離を検出する第２の検出素子と、
    　前記第２の検出素子からの検出信号に応じて、前記複数の共鳴素子と前記情報記録媒体との間の距離が一定になるように、前記複数の共鳴素子を前記情報記録媒体の表面に垂直な方向に移動させる第２の移動素子とをさらに備えることを特徴とする請求項１に記載の光情報装置。     A second detection element for detecting a distance between the plurality of resonance elements and the information recording medium;
    The plurality of resonance elements are perpendicular to the surface of the information recording medium so that distances between the plurality of resonance elements and the information recording medium are constant according to a detection signal from the second detection element. The optical information apparatus according to claim 1, further comprising a second moving element that moves in a specific direction.
  5. 　前記第１の検出素子は、複数の受光素子を含み、
    　前記光情報装置は、前記複数の共鳴素子からの光を前記複数の受光素子に導く複数の導波路をさらに備えることを特徴とする請求項１～４のいずれかに記載の光情報装置。     The first detection element includes a plurality of light receiving elements,
    The optical information device according to any one of claims 1 to 4, further comprising a plurality of waveguides for guiding light from the plurality of resonance elements to the plurality of light receiving elements.
  6. 　前記光源は、それぞれ波長の異なる光を出射する複数の光源を含み、
    　前記複数の共鳴素子は、前記複数の光源のそれぞれから出射された光の周波数を共鳴周波数とする形状又は材質で形成され、
    　前記第１の検出素子は、複数の受光素子を含み、
    　前記光情報装置は、前記複数の共鳴素子からの周波数の異なる複数の光を分離して、前記複数の光のそれぞれを対応する前記複数の受光素子に導く光学素子をさらに備えることを特徴とする請求項１～４のいずれかに記載の光情報装置。     The light source includes a plurality of light sources that emit light having different wavelengths,
    The plurality of resonance elements are formed of a shape or material having a resonance frequency as a frequency of light emitted from each of the plurality of light sources,
    The first detection element includes a plurality of light receiving elements,
    The optical information device further includes an optical element that separates a plurality of lights having different frequencies from the plurality of resonant elements and guides each of the plurality of lights to the corresponding plurality of light receiving elements. The optical information device according to any one of claims 1 to 4.
  7. 　前記第１の検出素子は、前記複数の共鳴素子から発生する近接場光を検出可能な範囲に配置された複数の受光素子を含むことを特徴とする請求項１～４のいずれかにに記載の光情報装置。 The first detection element includes a plurality of light receiving elements arranged in a range in which near-field light generated from the plurality of resonance elements can be detected. Optical information device.
  8. 　前記トラックは、列状に配置された微粒子により規定されることを特徴とする請求項１～７のいずれかに記載の光情報装置。 8. The optical information device according to claim 1, wherein the track is defined by fine particles arranged in a line.
  9. 　前記トラックは、グルーブにより規定されることを特徴とする請求項１～７のいずれかに記載の光情報装置。 8. The optical information device according to claim 1, wherein the track is defined by a groove.
  10. 　前記複数の共鳴素子間の前記トラックに垂直な方向の距離は、トラックピッチの半分であることを特徴とする請求項１～９のいずれかに記載の光情報装置。 10. The optical information device according to claim 1, wherein a distance between the plurality of resonance elements in a direction perpendicular to the track is a half of a track pitch.
  11. 　前記光源から前記複数の共鳴素子に入射する入射光の偏光方向は、前記情報記録媒体の表面に垂直な方向であることを特徴とする請求項１～１０のいずれかに記載の光情報装置。 11. The optical information device according to claim 1, wherein a polarization direction of incident light incident on the plurality of resonance elements from the light source is a direction perpendicular to a surface of the information recording medium.
  12. 　前記光源から前記複数の共鳴素子に入射する入射光の偏光方向は、前記情報記録媒体の表面に対して平行な方向であることを特徴とする請求項１～１０のいずれかに記載の光情報装置。 The optical information according to any one of claims 1 to 10, wherein a polarization direction of incident light incident on the plurality of resonance elements from the light source is a direction parallel to a surface of the information recording medium. apparatus.
  13. 　前記保持素子は、前記複数の共鳴素子の位置を前記トラックの長手方向にずらして配置することを特徴とする請求項１～１２のいずれかに記載の光情報装置。 The optical information device according to any one of claims 1 to 12, wherein the holding element is arranged by shifting positions of the plurality of resonance elements in a longitudinal direction of the track.
  14. 　前記複数の共鳴素子間の前記トラックの長手方向の位置は、前記複数の共鳴素子のうちの１つの共鳴素子の前記トラックの長手方向の厚さ以上にずれていることを特徴とする請求項１１記載の光情報装置。 12. The position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the thickness in the longitudinal direction of the track of one resonance element of the plurality of resonance elements. The optical information device described.
  15. 　前記光源から前記複数の共鳴素子に入射する入射光の偏光方向は、前記情報記録媒体の表面に対して平行な方向かつ前記トラックに対して平行な方向であり、
    　前記複数の共鳴素子間の前記トラックの長手方向の位置は、前記複数の共鳴素子のうちの１つの共鳴素子の前記トラックの長手方向の長さ以上にずれていることを特徴とする請求項１２記載の光情報装置。     The polarization direction of incident light incident on the plurality of resonance elements from the light source is a direction parallel to the surface of the information recording medium and a direction parallel to the track,
    The position in the longitudinal direction of the track between the plurality of resonance elements is shifted by more than the length of the resonance direction of one of the plurality of resonance elements in the longitudinal direction of the track. The optical information device described.
  16. 　前記第１の検出素子によって検出された前記共鳴状態の変化に基づいて、前記情報記録媒体の表面に平行な面内における前記保持素子の傾きを表すヨーイング信号を演算するヨーイング信号演算回路と、
    　前記ヨーイング信号演算回路によって演算された前記ヨーイング信号に応じて前記保持素子を前記情報記録媒体の表面に平行な面内で回転させる回転素子とをさらに備えることを特徴とする請求項１～１５のいずれかに記載の光情報装置。     A yawing signal calculation circuit for calculating a yawing signal representing the inclination of the holding element in a plane parallel to the surface of the information recording medium based on the change in the resonance state detected by the first detection element;
    16. A rotating element that further rotates the holding element in a plane parallel to the surface of the information recording medium according to the yawing signal calculated by the yawing signal calculation circuit. The optical information device according to any one of the above.
  17. 　前記第１の検出素子は、前記複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力し、
    　前記ヨーイング信号演算回路は、前記複数の検出信号の前記トラックに垂直な方向の変位量に対する位相差を演算し、
    　前記回転素子は、前記位相差がπラジアンとなるように前記保持素子を前記情報記録媒体の表面に平行な面内で回転させることを特徴とする請求項１６記載の光情報装置。     The first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements,
    The yawing signal calculation circuit calculates a phase difference with respect to a displacement amount in a direction perpendicular to the track of the plurality of detection signals,
    17. The optical information device according to claim 16, wherein the rotating element rotates the holding element in a plane parallel to the surface of the information recording medium so that the phase difference is π radians.
  18. 　前記第１の検出素子は、前記複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力し、
    　前記トラッキング信号演算回路は、前記第１の検出素子によって出力された前記複数の検出信号の差を前記トラッキング信号として演算することを特徴とする請求項１～１７のいずれかに記載の光情報装置。     The first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements,
    18. The optical information device according to claim 1, wherein the tracking signal calculation circuit calculates a difference between the plurality of detection signals output by the first detection element as the tracking signal. .
  19. 　前記第１の検出素子は、前記複数の共鳴素子の各々の共鳴状態の変化を表す複数の検出信号を出力し、
    　前記トラッキング信号演算回路は、前記複数の検出信号に基づいて、前記複数の共鳴素子の前記トラックからの位置ずれを補正するための補正値を演算し、演算した前記補正値に基づいて補正した前記複数の検出信号の差を前記トラッキング信号として演算することを特徴とする請求項１～１７のいずれかに記載の光情報装置。     The first detection element outputs a plurality of detection signals representing changes in the resonance state of each of the plurality of resonance elements,
    The tracking signal calculation circuit calculates a correction value for correcting a positional deviation of the plurality of resonance elements from the track based on the plurality of detection signals, and corrects based on the calculated correction value. The optical information device according to any one of claims 1 to 17, wherein a difference between a plurality of detection signals is calculated as the tracking signal.
  20. 　トラックを有する情報記録媒体に情報を記録又は再生する光情報装置におけるトラッキング方法であって、
    　前記情報記録媒体と相互作用し、前記トラックからの距離に応じて共鳴状態が変化する複数の共鳴素子に光源からの光を入射させる光入射ステップと、
    　前記複数の共鳴素子の各々の共鳴状態の変化を個別に検出する検出ステップと、
    　前記検出ステップにおいて検出された前記共鳴状態の変化に基づいてトラッキング信号を演算するトラッキング信号演算ステップと、
    　前記トラッキング信号演算ステップにおいて演算された前記トラッキング信号に応じて、前記複数の共鳴素子の位置を前記トラックに垂直な方向にずらして配置し、かつ前記複数の共鳴素子間の距離を一定に固定して保持する保持素子をトラックに垂直な方向に移動させる移動ステップと、
    を包含することを特徴とするトラッキング方法。     A tracking method in an optical information apparatus for recording or reproducing information on an information recording medium having a track,
    A light incident step for causing light from a light source to enter a plurality of resonance elements that interact with the information recording medium and change a resonance state according to a distance from the track;
    A detection step of individually detecting a change in resonance state of each of the plurality of resonance elements;
    A tracking signal calculation step for calculating a tracking signal based on the change in the resonance state detected in the detection step;
    In accordance with the tracking signal calculated in the tracking signal calculating step, the positions of the plurality of resonance elements are shifted in a direction perpendicular to the track, and the distance between the plurality of resonance elements is fixed. Moving the holding element to move in a direction perpendicular to the track;
    The tracking method characterized by including.
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