WO2007108446A1 - tête optique, dispositif à disque optique et procédé de fabrication de tête optique - Google Patents

tête optique, dispositif à disque optique et procédé de fabrication de tête optique Download PDF

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Publication number
WO2007108446A1
WO2007108446A1 PCT/JP2007/055546 JP2007055546W WO2007108446A1 WO 2007108446 A1 WO2007108446 A1 WO 2007108446A1 JP 2007055546 W JP2007055546 W JP 2007055546W WO 2007108446 A1 WO2007108446 A1 WO 2007108446A1
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WO
WIPO (PCT)
Prior art keywords
optical
light
composite element
optical axis
optical head
Prior art date
Application number
PCT/JP2007/055546
Other languages
English (en)
Japanese (ja)
Inventor
Akihiro Arai
Original Assignee
Matsushita Electric Industrial Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co., Ltd. filed Critical Matsushita Electric Industrial Co., Ltd.
Priority to JP2008506296A priority Critical patent/JPWO2007108446A1/ja
Publication of WO2007108446A1 publication Critical patent/WO2007108446A1/fr

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Classifications

    • 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
    • G11B7/22—Apparatus or processes for the manufacture of optical heads, e.g. assembly
    • 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
    • G11B7/1353—Diffractive elements, e.g. holograms or gratings
    • 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
    • G11B7/1378—Separate aberration correction lenses; Cylindrical lenses to generate astigmatism; Beam expanders
    • 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
    • G11B7/1392—Means for controlling the beam wavefront, e.g. for correction of aberration
    • G11B7/13925—Means for controlling the beam wavefront, e.g. for correction of aberration active, e.g. controlled by electrical or mechanical means

Definitions

  • OPTICAL HEAD OPTICAL DISK DEVICE
  • OPTICAL HEAD MANUFACTURING METHOD
  • the present invention relates to a method of manufacturing an optical head for optically recording and / or reproducing information to / from an information recording medium such as an optical disc, and the optical head. More specifically, the present invention relates to a method for adjusting the arrangement of optical elements in an optical head, and an optical head in which the arrangement of optical elements is adjusted.
  • a light source with a wavelength of about 405 nm shorter than the wavelength used for CDs and DVDs in recent years (about 780 nm and about 650 nm) and a relatively large objective lens with a numerical aperture of 0.65-0.85 are available. It has come to be used.
  • Patent Document 1 discloses a conventional optical head in which the longitudinal chromatic aberration of the objective lens is corrected. Disclosure.
  • FIG. 11 shows the configuration of a conventional optical head.
  • the conventional optical head includes a laser light source 101, a beam splitter 102, a diffraction integrated collimator 103, an objective lens 104, a detection optical system 106, and a light detection unit 107.
  • the diffractive integrated collimator 103 is a lens composed of, for example, a refracting surface and a diffractive lens surface, and the diffractive lens surface has a positive power.
  • the positive power means the same refractive power as the power of the convex lens.
  • FIG. 11 shows the optical axis 108 of the diffraction integrated collimator 103.
  • the light emitted from the laser light source 101 is reflected by the beam splitter 103, converted into substantially parallel light by the diffraction integrated collimator 103, and condensed on the information recording surface of the optical disk 105 by the objective lens 104.
  • the light reflected by the optical disk 105 passes through the objective lens 104 again, is converted into convergent light by the diffraction integrated collimator 103, passes through the beam splitter 102, and is guided to the light detection unit 107 by the detection optical system 106. .
  • the axial chromatic aberration of the objective lens 104 can be corrected by appropriately distributing the power of the refracting surface and the diffractive lens surface of the diffractive integrated collimator 103.
  • This principle is not limited to the above configuration.
  • one surface of the objective lens is a diffractive lens surface, it is possible to correct axial chromatic aberration by the same principle.
  • the above-described conventional technique suppresses the manufacturing cost of the optical head by forming a diffraction lens surface on a collimator having a shape that can be easily processed.
  • Patent Document 1 Japanese Patent Laid-Open No. 2001-108894 (page 4-11, Fig. 1)
  • chromatic aberration corresponding to the amount of decentration
  • the wavelength of the laser light varies depending on the amount of output light. Therefore, the wavelength differs between information reproduction with a relatively small amount of output light and information recording with a large amount of output light. It should be noted that wavelength fluctuations occur instantaneously when switching between recording and playback operations. Due to the lateral chromatic aberration caused by this wavelength variation, the light spot position moves instantaneously. If this instantaneous movement occurs in a direction perpendicular to the information track of the optical disk (that is, the radial direction of the disk), the tracking servo cannot follow and tracking control becomes unstable.
  • An object of the present invention is to provide a structure for adjusting the position of an optical element that corrects chromatic aberration, and to make the optical axis of the optical element coincide with the optical axis of an objective lens by the structure. It is an object to provide a head and an optical disk device including the optical head. Means for solving the problem
  • An optical head is disposed on an optical path from a light source that emits light, a condensing optical system that includes an objective lens that condenses the light onto an optical disc, and the light source to the objective lens. And a correction element that corrects chromatic aberration of the objective lens caused by fluctuations in the wavelength of the light, and a diffraction grating that deflects the light reflected by the optical disc in a plurality of directions.
  • the diffraction grating and the correction element constitute a composite element integrated so that their optical axes coincide with each other, and the optical axis of the composite element and the condensing optical system It has been adjusted to match the optical axis.
  • the optical axis of the composite element may be fixed at a position that coincides with the optical axis of the condensing optical system among positions on a plane orthogonal to the optical axis of the condensing optical system. ⁇ .
  • the optical head further includes a base having at least one end face defining a plane perpendicular to the optical axis of the condensing optical system, and the composite element is fixed on the at least one end face. May be.
  • the optical head further includes a light receiving unit that detects light reflected by the optical disc, and the diffraction grating includes a plurality of detectors for detecting a push signal in the radial direction of the optical disc based on the reflected light. It has a diffractive region.
  • the optical disc has one or more tracks, the diffraction grating has two diffraction regions divided by a dividing line corresponding to a direction along the tracks, and the composite element is The optical axis of the composite element is adjusted and fixed at a position that coincides with the optical axis of the condensing optical system in a range on the plane that is movable in a direction perpendicular to the dividing line. Also good.
  • the optical disc has one or more tracks, and the diffraction grating includes a first dividing line corresponding to a direction along the track and a second dividing line orthogonal to the first dividing line.
  • the divided element has four diffractive regions, and the composite element is movable on the plane in a first direction orthogonal to the first dividing line and a direction orthogonal to the second dividing line.
  • the optical axis of the composite element coincides with the optical axis of the condensing optical system. It can be adjusted and fixed.
  • the composite element may be configured by the correction element, the diffraction grating, and a member cover that physically fixes the correction element and the diffraction grating.
  • the composite element may be configured by adhering the correction element and the diffraction grating.
  • An optical disc device includes an optical head having any of the above-described features, a motor that rotates an optical disc, and a control unit that controls the optical head and the motor.
  • the control unit controls the optical head so that light is continuously collected on the recording layer of the optical disc based on a signal output from the optical head, and performs information recording and Z or reproduction. .
  • An optical head manufacturing method includes a light source that emits light, a condensing optical system that includes an objective lens that condenses the light on an optical disc, and an optical path from the light source to the objective lens.
  • An optical element that is arranged and corrects a chromatic aberration of the objective lens that occurs due to fluctuations in the wavelength of the light, and a diffraction grating that deflects the light reflected by the optical disc in a plurality of directions.
  • the optical head manufacturing method includes the step of preparing the condensing optical system, and a composite element integrated so that the optical axis of the diffraction grating and the optical axis of the correction element are aligned. And adjusting the optical axis of the composite element so as to coincide with the optical axis of the condensing optical system on a plane orthogonal to the optical axis of the condensing optical system.
  • the adjusting step may be performed such that an optical axis of the composite element coincides with an optical axis of the condensing optical system while the composite element is brought into contact with a base having the flat surface.
  • the optical axes of the lens that generates chromatic aberration in the optical head and the lens that corrects chromatic aberration coincide with each other, lateral chromatic aberration caused by decentration of the optical system can be reduced. Can do. As a result, an optical head capable of stable tracking control even when an abrupt wavelength change occurs can be manufactured.
  • FIG. 1 shows an optical head 50 during assembly according to an embodiment of the present invention.
  • ⁇ 2 A diagram showing an example of the configuration of the chromatic aberration correcting element 4.
  • ⁇ 3 A diagram showing an example of the configuration of the diffraction element 3.
  • FIG. 4 A view showing a base 55 and an end surface (pressing surface) 54 of the base 55 that defines a plane orthogonal to the optical axis of the objective lens 7.
  • FIG. 4 A view showing a base 55 and an end surface (pressing surface) 54 of the base 55 that defines a plane orthogonal to the optical axis of the objective lens 7.
  • FIG. 5 (a) is a diagram showing the position of the light 14 passing through the diffraction element 3, and (b) is a diagram showing the waveforms of the signals S12 and S13.
  • FIG. 6 (a) is a diagram showing the light 14 equally divided into two by the dividing line 15, and (b) shows the level change of the signals S 12 and S 13 when the position of the composite element is adjusted.
  • FIG. 6 (a) is a diagram showing the light 14 equally divided into two by the dividing line 15, and (b) shows the level change of the signals S 12 and S 13 when the position of the composite element is adjusted.
  • FIG. 7 shows the optical head 56 after assembly.
  • FIG. 8 is a diagram showing an example of the configuration of a diffraction element 30 having two dividing lines 20 and 21.
  • FIG. 9 is a diagram showing a schematic configuration of an optical disc device 90 according to an embodiment of the present invention.
  • FIG. 10 is a view showing an example of a base provided with a protrusion 60.
  • FIG. 11 is a diagram showing a configuration of a conventional optical head.
  • FIG. 1 shows an optical head 50 during assembly according to this embodiment.
  • Figure 1 shows the process of incorporating the optical head 50 components and adjusting their placement! /
  • the optical head 50 includes a light source 1, a beam splitter 2, a diffraction element 3 that splits light, a color difference correction element 4, a collimator 5, an aperture stop 6, an objective lens 7, and light detection. With a vessel 11. In FIG. 1, an optical disk 8 is also shown for reference.
  • an optical system of a general optical head further requires a focus detection unit, a tracking detection unit, an information signal detection unit, and the like, but their description is omitted in FIG. These configurations will be described later with reference to FIG.
  • a solid line 9 indicates the principal ray (optical axis) of the condensing optical system from the light source 1 to the objective lens 7.
  • a one-dot chain line 10 indicates the optical axis of the collimator 5.
  • FIG. 1 shows a state where the optical axis of the condensing optical system 7 and the optical axis 10 of the collimator are decentered. Eccentricity occurs because light propagates in parallel between the objective lens and the collimator, making it difficult to align their optical axes.
  • the main light beam 9 passes through the center of the aperture stop 6.
  • the principal ray 9 substantially coincides with the optical axis of the objective lens 7.
  • the principal ray 9 will be described as being the optical axis of the objective lens 7.
  • the diffractive element 3 and the chromatic aberration correcting element 4 are integrally held by a holder 53.
  • the optical axes of the diffraction element 3 and the chromatic aberration correction element 4 are adjusted so as to coincide with each other, and the state is maintained after fixing.
  • the optical axis of the diffraction element 3 is an axis perpendicular to the paper surface passing through a point on the dividing line 15 (FIG. 3 described later) of the diffraction element 3 (for example, the midpoint of the dividing line 15).
  • the integrated diffraction element 3 and chromatic aberration correction element 4 are also referred to as “composite element”.
  • the two optical axes of the diffraction element 3 and the chromatic aberration correction element 4 overlap each other and are recognized as one optical axis, the one optical axis is hereinafter referred to as “the optical axis of the composite element”.
  • FIG. 2 shows an example of the configuration of the chromatic aberration correcting element 4.
  • the chromatic aberration correcting element 4 has a concave refracting surface and a diffractive lens surface.
  • the concave surface is arranged on the light source 1 side.
  • the diffractive lens surface facing the concave surface has positive power. Since the positive power neglects the negative negative power, the overall power of the chromatic aberration correction element 4 is small.
  • the wavelength When the wavelength is shortened, the positive power of the diffractive lens surface is reduced and the negative power of the concave surface is superior, so that the light passing therethrough is more diverged. Therefore, when the wavelength is shortened, the light from the light source 1 can be intensified by the color difference correction element 4. As a result, the light output from the chromatic aberration correcting element 4 and passing through the collimator 5 becomes divergent light. As a result, the axial color difference of the objective lens 7 is corrected.
  • FIG. 3 shows an example of the configuration of the diffraction element 3.
  • the diffractive element 3 has two diffractive regions 12 and 13 in which diffraction gratings having different periods or directions are formed.
  • the diffraction regions 12 and 13 are arranged with the dividing line 15 as a boundary.
  • the dividing line 15 corresponds to a direction parallel to the information track (a direction along the information track).
  • the passing light 14 is shown in FIG.
  • the diffractive element 3 is moved in the X direction indicated by the double-headed arrow in FIG.
  • the laser light emitted from the light source 1 passes through the beam splitter 2, the diffraction element 3, and the chromatic aberration correction element 4, is converted into parallel light by the collimator 5, passes through the aperture stop 6, and is recorded on the optical disk 8 by the objective lens 7. Focused on the recording surface.
  • the light reflected by the optical disk 8 is incident on the diffraction element 3 again through the objective lens 7, the aperture stop 6, the collimator 5, and the color difference correction element 4.
  • the diffraction element 3 splits and diffracts the light.
  • the diffracted light is reflected by the beam splitter 2, guided to the photodetector 11, and the amount of each divided light is detected.
  • the optical axis of the objective lens 7 that generates chromatic aberration and the optical axis of the composite element having the function of correcting the chromatic aberration described above are shifted (that is, eccentricity occurs), the amount of eccentricity is increased.
  • Corresponding lateral chromatic aberration occurs in the direction perpendicular to their optical axes.
  • a configuration that allows the optical axis of the composite element to coincide with the optical axis of the objective lens 7 by moving the holder 53 is introduced.
  • a base having the plane is provided so that the composite element can be moved on a plane orthogonal to the optical axis of the objective lens 7.
  • FIG. 4 shows the base 55 and an end surface (pressing surface) 54 of the base 55 that defines a plane orthogonal to the optical axis of the objective lens 7.
  • a composite element composed of the diffractive element 3 and the chromatic aberration correcting element 4 is disposed in contact with the end face 54.
  • the position of the composite element is adjusted by moving the holder 53 in the direction along the plane. During movement, the composite element is pressed against the end face 54, and the optical axis of the composite element and the optical axis of the objective lens 7 are always parallel.
  • the chromatic aberration correcting element 4 is in contact with the end face 54, but this is an example.
  • the end face 54 may be provided on the diffraction element 3 side so that the diffraction element 3 is in contact with the end face 54.
  • the moving direction of the holder 53 is the X direction shown in FIG. 4 when the diffractive element 3 shown in FIG. 3 is used.
  • the X direction in Fig. 3 and the X direction in Fig. 4 correspond to the same direction.
  • the moving direction of the holder 53 is the X direction and the Y direction shown in FIG.
  • the X and Y directions in Fig. 8 correspond to the same directions as the X and Y directions in Fig. 4, respectively.
  • FIG. 10 shows an example of a configuration in which the diffraction element 3 and the chromatic aberration correction element 4 cannot move.
  • FIG. 10 shows an example of a base having a protrusion 60.
  • the protrusion 60 is for determining the positions of the diffractive element 3 and the chromatic aberration correcting element 4 rather than for adjusting the positions of the diffractive element 3 and the color difference correcting element 4.
  • the position adjusting method according to the present invention cannot be adopted.
  • the holder 53 is moved by the control circuit 51 and the actuator 52 shown in FIG. Specifically, it is as follows.
  • the control circuit 51 receives at least two signals output from the photodetector 11. The level of each signal corresponds to the amount of light incident on a different light receiving area of the photodetector 11. control The circuit 51 generates a control signal based on these signals and outputs it to the actuator 52.
  • the actuator 52 is physically connected to the holder 53, and moves the holder 53 based on a control signal.
  • the direction indicated by the arrow in FIG. 1 corresponds to the X direction in FIG.
  • the light source 1 is caused to emit light, and the laser light is condensed on the optical disc 8. Then, the light reflected by the optical disk 8 and divided by the diffraction element 3 is detected by the photodetector 11.
  • the focus control may be performed by incorporating the optical head 50 being assembled into a device having a function equivalent to that of FIG. 9 described later.
  • the optical axis of the composite element and the optical axis of the objective lens 7 coincide with each other so that the laser beam is incident on a position off the optical axis of the diffraction element 3. To do.
  • FIG. 5A shows the position of the light 14 passing through the diffraction element 3.
  • the light transmitted through the diffraction regions 12 and 13 of the diffraction element 3 is detected separately by the photodetector 11.
  • the light diffracted by the diffraction region 12 is detected by the photodetector 11 and a signal S12 is output.
  • the light diffracted by the diffraction region 13 is detected by the photodetector 11 and a signal S13 is output.
  • FIG. 5 (b) shows the waveforms of the signals S12 and S13.
  • the level of signal S12 is a
  • the level of signal S13 is b (b a).
  • the level of the signal S12 is higher than that of the signal S13.
  • the control circuit 51 controls the actuator 52 to adjust the position of the composite element (that is, the diffraction element 3) so that the signal S12 and the S13 force S become the same level. This means that the position of the composite element is adjusted so that the light is equally divided into two by the dividing line 15.
  • the optical disk 8 is a disk that does not have a pit Z mark and has a reflective layer. This is a very easy force to adjust the levels of signals S12 and S13. Since the waveform component of the pit Z mark on optical disc 8 is not superimposed on the reflected light, the waveform in Fig. 5 (b) is a straight line. Disc with pit Z mark When used, the wave formation due to the pit Z mark is superimposed on both signals S12 and S13.
  • FIG. 6 (a) shows light 14 that is equally divided into two by a dividing line 15.
  • Figure 6 (b) shows the level change of the signals S12 and S13 when the position of the composite element is adjusted. The composite element is moved from the position shown in FIG. 5 (a) to the position shown in FIG. 6 (a). At this time, the light 14 itself has not changed.
  • FIG. 7 shows the optical head 56 after assembly.
  • the optical axis of the objective lens 7 (the optical axis of the principal ray 9) also coincides with the optical axis of the chromatic aberration correcting element 4.
  • the eccentric component in the direction perpendicular to the information track in the plane of the optical disk 8 is removed, and the occurrence of lateral chromatic aberration can be suppressed.
  • the holder 53 is an example for holding the diffraction element 3 and the chromatic aberration correction element 4 in a state where the optical axes coincide with each other.
  • Other configurations can be adopted as long as the diffractive element 3 and the chromatic aberration correcting element 4 can be simultaneously moved in a state where the optical axes coincide with each other.
  • the diffraction element 3 and the chromatic aberration correction element are The element 4 may be fixed, or the diffraction element 3 and the chromatic aberration correction element 4 may be bonded to each other.
  • one end surface of the base 55 that is a structure of the optical head is formed as a plane orthogonal to the optical axis of the objective lens 7, thereby matching the coincident optical axis of the composite element with the objective lens.
  • the optical axis in Fig. 7 is kept parallel.
  • This structure is an example.
  • a plane orthogonal to the optical axis of the objective lens 7 can be defined, an example in which the base 55 is not used may be adopted.
  • the composite element is moved along such a plane, it may be adjusted by a human instead of the adjustment using the control circuit 51, the actuator 52, and the like.
  • the diffraction region of the diffraction element 3 is divided into two by one dividing line.
  • the number of dividing lines may be plural.
  • FIG. 8 shows an example of the configuration of the diffraction element 30 having two dividing lines 20 and 21.
  • the diffractive element 30 is used in place of the diffractive element 3 described above.
  • the diffraction element 30 is divided into four regions 16, 17, 18 and 19 by two dividing lines 20 and 21. In each region, diffraction gratings having different periods or orientations are formed.
  • the passing light 22 is shown in FIG.
  • the dividing line 20 corresponds to the direction perpendicular to the information track
  • the dividing line 21 corresponds to the direction parallel to the information track.
  • the position of the composite element composed of the diffractive element 30 and the chromatic aberration correcting element 4 can be adjusted in both the X direction and the Y direction shown in FIG.
  • the optical axis of the diffractive element 30 and the optical axis of the chromatic aberration correcting element 4 are the same.
  • the optical axis of the diffractive element 30 is an axis perpendicular to the paper surface passing through the intersection of the dividing lines 20 and 21 of the diffractive element 3.
  • the adjustment method is the same as the adjustment method shown in Figs. That is, by collecting the light on the optical disk 8 and measuring the signal detected by dividing the reflected light by the diffraction element 3, the amount of light that passed through the regions 16 to 19 was detected, and the four obtained The position of the composite element may be adjusted so that the signal levels are equal. Since the principal ray 9 is adjusted so as to pass through the intersection of the dividing lines 20 and 21, the optical axis of the chromatic aberration correcting element 4 and the principal ray 9, that is, the optical axis of the objective lens 7 can be matched.
  • the occurrence of lateral chromatic aberration is prevented in both the direction perpendicular to the information track and the direction parallel to the information track in the plane of the optical disc 8, and a sudden wave
  • an optical head can be produced without causing tracking control and optical spot movement that destabilizes the information recording state.
  • the composite element is disposed between the light source 1 and the collimator 5.
  • the same effect can be obtained by arranging the composite element between the collimator 5 and the objective lens 7.
  • optical head described in the above embodiment has been described as being incorporated in an optical disc apparatus. Therefore, the configuration of an optical disc apparatus provided with such an optical head will be described with reference to FIG.
  • FIG. 9 shows a schematic configuration of the optical disc apparatus 90 according to the present embodiment.
  • the optical disk device 90 includes an optical head 70, a disk motor 72 that rotates the optical disk 8, and a portion that performs various signal processing.
  • the optical head 70 is an optical head obtained by replacing the optical head 51 shown in FIG. 7 or the diffractive element 3 of the optical head 51 with the diffractive element 30 shown in FIG.
  • the output of the optical head 70 is sent to the encoder Z decoder 78 via the front end signal processing unit 76.
  • the encoder Z decoder 78 decodes data recorded on the optical disc 2 based on a signal obtained by the optical head 70 when reading data.
  • the decrypted data is output to a host device (not shown).
  • the encoder Z decoder 78 encodes the user data, generates a signal to be written on the optical disk 2, and sends it to the optical head 70.
  • the front end signal processing unit 76 generates a reproduction signal based on the output of the optical head 70, while generating a focus error signal FE and a tracking error signal TE.
  • the focus error signal FE and tracking error signal TE are sent to the servo controller 80.
  • the servo control unit 80 controls the disk motor 72 via the driver amplifier 74, and controls the position of the objective lens via an actuator (not shown) in the optical head 70.
  • the servo control unit 80 controls the position of the objective lens in a direction perpendicular to the information recording layer of the optical disc 8 based on the focus error signal FE. As a result, the focal point of the light continues to be positioned on the information recording layer to be reproduced or recorded.
  • the servo control unit 80 controls the position of the objective lens in the radius direction of the optical disc 8 based on the tracking error signal TE! As a result, the focus of light continues and the information to be reproduced or recorded follow the track of the information recording layer.
  • the components such as the encoder Z decoder 78 and the servo control unit 80 are controlled by the CPU 79.
  • optical head of the present invention and the optical disk apparatus using the same are useful for an optical disk apparatus for BD (Blu-ray Disc) or HD-DVD that requires correction of axial chromatic aberration with a large numerical aperture of the objective lens.
  • BD Blu-ray Disc
  • HD-DVD High-density Digital

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  • Optics & Photonics (AREA)
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Abstract

L'invention concerne une tête optique ou similaire caractérisée en ce que la position d'un élément optique permettant de corriger l'aberration de couleur est ajustée. La tête optique est pourvue d'une source de lumière permettant de produire de la lumière ; d'un système optique de focalisation pourvu d'une lentille d'objectif permettant de focaliser la lumière sur un disque optique ; d'un élément de correction disposé sur un trajet optique à partir de la source de lumière vers la lentille d'objectif permettant de corriger l'aberration de couleur de la lentille d'objectif générée du fait de la fluctuation de longueur d'onde de la lumière ; et d'un réseau de diffraction permettant de dévier la lumière réfléchie par le disque optique dans une pluralité de directions. Le réseau de diffraction et l'élément de correction constituent un élément composite intégré pour que les axes optiques correspondent. La position de l'élément composite est ajustée de sorte que l'axe optique de l'élément composite et celui du système optique de focalisation correspondent l'un à l'autre.
PCT/JP2007/055546 2006-03-23 2007-03-19 tête optique, dispositif à disque optique et procédé de fabrication de tête optique WO2007108446A1 (fr)

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JP2008506296A JPWO2007108446A1 (ja) 2006-03-23 2007-03-19 光学ヘッド、光ディスク装置および光学ヘッドの製造方法

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JP2006080271 2006-03-23
JP2006-080271 2006-03-23

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011023095A (ja) * 2009-06-16 2011-02-03 Panasonic Corp 光ディスク装置
JP2022520462A (ja) * 2019-02-16 2022-03-30 フラウンホーファー－ゲゼルシャフト ツル フェルデルング デル アンゲヴァンテン フォルシュング エー ファウ ガラス基板の強度を高める方法

Citations (5)

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JPH1139697A (ja) * 1997-07-16 1999-02-12 Sankyo Seiki Mfg Co Ltd 光ヘッド装置
JP2003323735A (ja) * 2002-02-27 2003-11-14 Ricoh Co Ltd 光ピックアップとこれを用いる光情報処理装置
JP2004111012A (ja) * 2002-07-22 2004-04-08 Ricoh Co Ltd 光ピックアップ及びこれを用いる光情報処理装置
JP2005093008A (ja) * 2003-09-18 2005-04-07 Ricoh Co Ltd 光ピックアップ装置および光ディスクドライブ装置

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JPH02270139A (ja) * 1989-04-10 1990-11-05 Matsushita Electric Ind Co Ltd 光ピックアップ装置
JPH1139697A (ja) * 1997-07-16 1999-02-12 Sankyo Seiki Mfg Co Ltd 光ヘッド装置
JP2003323735A (ja) * 2002-02-27 2003-11-14 Ricoh Co Ltd 光ピックアップとこれを用いる光情報処理装置
JP2004111012A (ja) * 2002-07-22 2004-04-08 Ricoh Co Ltd 光ピックアップ及びこれを用いる光情報処理装置
JP2005093008A (ja) * 2003-09-18 2005-04-07 Ricoh Co Ltd 光ピックアップ装置および光ディスクドライブ装置

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JP2011023095A (ja) * 2009-06-16 2011-02-03 Panasonic Corp 光ディスク装置
JP2022520462A (ja) * 2019-02-16 2022-03-30 フラウンホーファー－ゲゼルシャフト ツル フェルデルング デル アンゲヴァンテン フォルシュング エー ファウ ガラス基板の強度を高める方法
JP7431843B2 (ja) 2019-02-16 2024-02-15 フラウンホーファー－ゲゼルシャフト ツル フェルデルング デル アンゲヴァンテン フォルシュング エー ファウ ガラス基板の強度を高める方法

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