WO2010131406A1 - 光ヘッド装置、ホログラム素子、光集積素子、光情報処理装置および信号検出方法 - Google Patents
光ヘッド装置、ホログラム素子、光集積素子、光情報処理装置および信号検出方法 Download PDFInfo
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- WO2010131406A1 WO2010131406A1 PCT/JP2010/001929 JP2010001929W WO2010131406A1 WO 2010131406 A1 WO2010131406 A1 WO 2010131406A1 JP 2010001929 W JP2010001929 W JP 2010001929W WO 2010131406 A1 WO2010131406 A1 WO 2010131406A1
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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
- G11B7/12—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
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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
- G11B7/0906—Differential phase difference systems
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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
- G11B7/0908—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 focusing only
- G11B7/0909—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 focusing only by astigmatic methods
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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
- G11B7/0943—Methods and circuits for performing mathematical operations on individual detector segment outputs
Definitions
- the present invention relates to an optical head device, a hologram element, an optical integrated device, an optical information processing apparatus, and a signal detection method for recording / reproducing or erasing information stored on an optical medium such as an optical disk or an optical card.
- Servo technology for condensing a light spot at a desired recording / reproducing position is an indispensable technology in optical information recording including optical disks.
- a tracking error signal detection method is generally used by switching between a plurality of methods depending on the type of recording / reproducing medium. Therefore, the optical head device needs to detect a plurality of tracking error signals.
- DPD signal phase difference tracking signal
- PP signal push-pull signal
- an optical head device capable of detecting a DPD signal and a PP signal is also required in the Blue Ray system.
- a hologram element HOE; Holographic Optical Element
- FIG. 10 is a diagram showing a diffraction region of the optical head device according to the prior application.
- a semiconductor laser element 30, a light receiving element 40, a hologram element 20, and the like are shown.
- the semiconductor laser element 30 and the light receiving element 40 are fixed to the holding portion 741 in proximity.
- the holding unit 741 is fixed to the hologram element 20 in a desired positional relationship via another holding unit (not shown).
- the other holding unit may be an optical stage of the optical head device, but it constitutes a unit in which the hologram element 20, the semiconductor laser element 30, and the light receiving element 40 are integrated using a holding member different from the optical stage. May be. Such a unit configuration allows a stable optical system.
- the optical head device further includes a collimating lens 11 and an objective lens 12, and constitutes a condensing optical system for condensing the laser light on the optical disk 10 which is an information recording medium.
- the optical head device further includes a lens driving mechanism (not shown) that drives and displaces the objective lens 12 in the optical axis direction (z direction) of the objective lens 12 and the radial direction (x direction) of the optical disk 10.
- the direction of the optical axis of the condensing optical system is the Z-axis direction
- the radial direction (radial direction) of the optical disc 10 is the X direction
- the track direction of the optical disc 10 is referred to as the Y direction.
- the direction is defined based on the optical axis and the mapping of the optical disc 10.
- the light beam R0 emitted from the semiconductor laser element 30 passes through the hologram element 20 and is condensed on the information recording surface of the optical disk 10 by the collimator lens 11 and the objective lens 12. Reflected light from the optical disk 10 is converted by the objective lens 12 and the collimating lens 11 into light that converges at the light emitting point of the semiconductor laser element 30. This light enters the hologram element 20 and is diffracted. The diffracted light enters the light receiving element 40 and a signal is detected by the light receiving element 40.
- FIG. 11 is a diagram showing a diffraction region of the hologram element 20 in the optical head device according to the prior application.
- the grating pattern of the hologram element 20 is divided into a first diffraction region 261 and a second diffraction region 262 by a straight line L11 that passes through almost the center of the light beam and is parallel to the X axis.
- R0 is the reflected light from the optical disk 10 incident on the hologram element 20.
- R1 and R2 are lights diffracted by the optical disk 10 and generate light and dark according to the tracking position in a region that interferes with R0, that is, a region that overlaps.
- FIG. 12 is a diagram showing a light receiving region of the light receiving element 40 in the optical head device according to the prior application.
- the light receiving element 40 has a first light receiving region group 451 and a second light receiving region group 452.
- the first light receiving region group 451 is composed of a first light receiving region 451a and a second light receiving region 451b which are arranged to face each other with the first light receiving dividing line L71 substantially parallel to the X axis interposed therebetween.
- the region group 452 includes a third light receiving region 452a and a fourth light receiving region 452b that are arranged to face each other with the second light receiving dividing line L72 substantially parallel to the X axis interposed therebetween.
- the return light from the optical disc 10 straddles the first light receiving dividing line L71 of the first light receiving region group 451 and extends in the X direction to the first light receiving region 451a and the second light receiving region 451b.
- a grating pattern that has first coma aberration and converts it into incident light is formed.
- the return light from the optical disc 10 is crossed over the second light receiving division line L72 of the second light receiving region group 452 and is transferred to the third light receiving region 452a and the fourth light receiving region 452b.
- a grating pattern is formed which has a second coma aberration opposite to the polarity of one diffraction region 261 and converts it into incident light.
- the signal detected by the first light receiving region 451a is the first signal S1
- the signal detected by the second light receiving region 451b is the second signal S2
- the signal detected by the third light receiving region 452a is the third signal.
- Signal S3, a signal detected by the fourth light receiving region 452b is a fourth signal S4
- a sum signal of the first signal S1 and the fourth signal S4 is (S1 + S4)
- the second signal S2 and the second signal S4 The sum signal of the third signal S3 is (S2 + S3)
- the sum signal of the first signal S1 and the third signal S3 is (S1 + S3)
- the sum signal of the second signal S2 and the fourth signal S4 Is (S2 + S4)
- the focus error (FE) signal of this configuration is detected by the following equation.
- the target of calculation in the equation is the signal level (intensity) (the same applies to the following equations).
- TE PP (S1 + S3) ⁇ (S2 + S4) (Formula 2)
- TE DPD Phase (S1 + S4, S2 + S3) (Formula 3)
- Phase is a function for performing phase comparison (calculating phase difference) of two signals.
- FIG. 13A is a diagram illustrating an ideal state
- FIG. 13B is a diagram illustrating a light receiving region of the light receiving element 40 in a state where the light receiving element 40 is shifted in the radial direction (Y direction).
- the light rays R1 and R2 that generate the push-pull signal are incident as shown in the figure.
- the boundary line between the light beam R1 and the light beam R2 coincides with the first light receiving dividing line L71 and the second light receiving dividing line L72, and the signals in these two regions are detected without leaking to each other and pushed.
- the pull signal can be detected without problems.
- the light receiving element 40 is shifted in the tangential direction (Y direction) due to the adjustment shift (FIG. 13B)
- the light ray R2 is the region of the light ray R1 (second light receiving region 451b, fourth light receiving region). 452b). Therefore, the amplitude of the TE signal TE PP by the push-pull method expressed by the above equation 2 decreases. Further, the TE signal TE DPD by the DPD method expressed by the above equation 3 is also affected by crosstalk, and the signal deteriorates.
- the tracking error (TE) signal is easily affected by the displacement of the light receiving element 40 in the tangential direction (Y direction). For this reason, the subject that the highly accurate adjustment of the light receiving element 40 is required occurs.
- An object of the present invention is to provide an optical head device, a hologram element, an optical integrated device, an optical information processing apparatus, and a signal detection method capable of detecting a signal.
- an optical head device includes a light source that emits a light beam, and a condensing optical that receives the light beam and converges into a minute spot on an information recording medium having a track.
- An optical head device comprising: a system; a hologram element that diffracts the light beam reflected by the information recording medium; and a light receiving element that receives light diffracted by the hologram element, the light receiving element comprising: A first light receiving region for detecting at least the first signal S1, a second light receiving region for detecting the second signal S2, a third light receiving region for detecting the third signal S3, and a fourth signal.
- a fourth light receiving region for detecting S4, and the first light receiving region and the second light receiving region are disposed to face each other across the first light receiving dividing line, and The light receiving region and the fourth light receiving region are
- the hologram element has a first diffraction region and a second diffraction region, and the first diffraction region and the second diffraction region are
- the first diffraction region includes the first light receiving region and the first light receiving region, and is disposed with a region dividing line passing through the optical axis center of the condensing optical system and extending in a radial direction of the information recording medium.
- a grating pattern for generating diffracted light having a first wavefront incident on the second light receiving region is formed, and the second diffraction region is incident on the third light receiving region and the fourth light receiving region.
- a grating pattern for generating diffracted light having a second wavefront is formed, the first wavefront has a first coma aberration in a radial direction of the information recording medium, and the axis of the first coma aberration is The second wave is separated from the optical axis center of the condensing optical system.
- Has a second coma aberration in the radial direction of the information recording medium the axis of the second coma aberration is characterized by spaced apart from the optical axis center of the focusing optical system.
- the first and second wavefronts have first and second coma aberrations in the radial direction of the information recording medium, respectively, and the axes of the first and second coma aberrations are the condensing points. Since it is separated from the optical axis center of the optical system, the tracking signal component can be clearly separated even when the position of the light receiving element is shifted in that direction.
- the present invention is not only realized as an optical head device as described above, but also a hologram element that functions as a diffraction element that diffracts light, and has a first diffraction region and a second diffraction region,
- the first diffractive region and the second diffractive region are arranged with a region dividing line in between, and the first diffractive region has a diffracted light having a first coma aberration in the region dividing line direction.
- the second diffraction region generates diffracted light having a second coma aberration in the region dividing line direction, and the first coma aberration axis is separated from the region dividing line;
- the axis of the second coma aberration can also be realized as a hologram element characterized in that it is separated from the region dividing line.
- the present invention also provides an optical integrated circuit comprising: a light source that emits a light beam; a hologram element that diffracts the light beam reflected by an information recording medium; and a light receiving element that receives light diffracted by the hologram element.
- the light receiving element includes at least a first light receiving region for detecting the first signal S1, a second light receiving region for detecting the second signal S2, and a third signal S3 for detecting the third signal S3. 3 light receiving areas and a fourth light receiving area for detecting the fourth signal S4, and the first light receiving area and the second light receiving area face each other across the first light receiving dividing line.
- the third light receiving region and the fourth light receiving region are disposed to face each other with the second light receiving dividing line interposed therebetween, and the hologram element includes the first diffraction region and the first light receiving region.
- Two diffraction regions, the first diffraction region and the second diffraction region The region passes through the center of the optical axis of the condensing optical system and is arranged with a region dividing line extending in the radial direction of the information recording medium, and the first diffraction region includes the first light receiving region.
- a grating pattern for generating diffracted light having a first wavefront incident on the second light receiving region is formed, and the second diffraction region includes a third light receiving region and a fourth light receiving region.
- a grating pattern that generates diffracted light having a second wavefront that is incident is formed, and the first wavefront has a first coma aberration in a radial direction of the information recording medium, and an axis of the first coma aberration.
- the second wavefront Is spaced from the optical axis center of the condensing optical system, the second wavefront has a second coma aberration in the radial direction of the information recording medium, and the axis of the second coma aberration is It is separated from the center of the optical axis of the condensing optical system. It can be implemented as integrated optical devices.
- the present invention also provides a light source that emits a light beam, a condensing optical system that receives the light beam and converges it onto a fine spot on an information recording medium having a track, and the light beam reflected by the information recording medium.
- a signal detecting method in an optical head device comprising a hologram element that diffracts the light and a light receiving element that receives light diffracted by the hologram element, wherein the light receiving element detects at least a first signal S1.
- the first light receiving region and the second light receiving region are arranged to face each other across the first light receiving dividing line, and the third light receiving region and the fourth light receiving region are , Opposite the second light receiving parting line
- the hologram element has a first diffraction region and a second diffraction region, and the first diffraction region and the second diffraction region are optical axes of the condensing optical system.
- the signal detection method includes the first diffraction region and the second light reception region in the first diffraction region.
- the signal detection method is arranged with a region dividing line extending in the radial direction of the information recording medium passing through the center.
- the first wavefront has a first coma aberration in a radial direction of the information recording medium, and an axis of the first coma aberration is separated from an optical axis center of the condensing optical system;
- the second wavefront has a second coma aberration in a radial direction of the information recording medium.
- the shaft of the second coma aberration can also be implemented as a signal detection method characterized in that spaced apart from the optical axis center of the focusing optical system.
- the present invention is an optical information processing apparatus having the above optical head device, wherein the difference signal (S1-S2) between the first signal S1 and the second signal S2, or the third signal S3 It can also be realized as an optical information processing apparatus comprising a circuit that performs focus servo by a focus error signal generated by the difference signal (S3-S4) of the fourth signal S4 or both.
- the optical head device and the like of the present invention it is possible to reduce the influence of the tracking signal due to the positional deviation of the light receiving element, and to detect the tracking error signal that realizes more accurate and stable recording and / or reproduction. .
- FIG. 1 is a diagram showing a configuration of an optical head device according to Embodiment 1 of the present invention.
- FIG. 2 is a plan view showing the hologram element according to Embodiment 1 of the present invention.
- FIG. 3 is a plan view showing the light receiving element according to the first embodiment of the present invention.
- FIG. 4 is a diagram illustrating the calculation according to the first embodiment of the present invention.
- 5A to 5E are spot diagrams according to the first embodiment of the present invention.
- FIG. 6 is a diagram showing a focus error signal according to the first embodiment of the present invention.
- FIG. 7 is a diagram showing the configuration of the optical head device according to Embodiment 2 of the present invention.
- FIG. 8 is a plan view showing the light receiving element according to the second embodiment of the present invention.
- FIG. 1 is a diagram showing a configuration of an optical head device according to Embodiment 1 of the present invention.
- FIG. 2 is a plan view showing the hologram element according to Embod
- FIG. 9 is a configuration diagram of the optical information processing apparatus according to the third embodiment of the present invention.
- FIG. 10 is a diagram showing the configuration of the optical head device according to the prior application.
- FIG. 11 is a plan view showing a hologram element of the optical head device according to the prior application.
- FIG. 12 is a plan view showing a light receiving element of the optical head device according to the prior application.
- FIGS. 13A and 13B are spot states on the light receiving element of the optical head device according to the prior application.
- FIG. 1 is a diagram schematically showing a configuration of an optical head device according to Embodiment 1 of the present invention.
- This optical head device includes a semiconductor laser element 30 that emits a light beam, and a condensing optical system (collimator lens 11 and objective lens) that receives the light beam and converges on a fine spot onto an optical disk (information recording medium) 10 having a track. 12) A hologram element 20 that diffracts the light beam reflected by the optical disc 10 and a light receiving element 40 that receives the light diffracted by the hologram element.
- the semiconductor laser element 30 and the light receiving element 40 are fixed to the holding portion 741 in proximity.
- the holding unit 741 is fixed to the hologram element 20 in a desired positional relationship via another holding unit (not shown).
- the holding unit 741 may be an optical stage of an optical head device.
- a stable optical can be obtained by using an optical integrated element in which the semiconductor laser element 30 and the light receiving element 40 are integrated using a holding member different from the optical stage.
- the system can be configured.
- further stabilization can be achieved by forming an optical integrated device in which the semiconductor laser element 30, the light receiving element 40, and the hologram element 20 are integrated.
- the collimating lens 11 and the objective lens 12 constitute a condensing optical system that condenses laser light on the optical disk 10 that is an information recording medium.
- the optical head device further includes a lens driving mechanism (not shown) that drives and displaces the objective lens 12 in the optical axis direction (z direction) of the objective lens 12 and the radial direction (x direction) of the optical disk 10.
- the direction to the optical axis of the condensing optical system is the Z-axis direction
- the radial direction (radial direction) of the optical disk 10 is the X direction
- the track direction of the optical disk 10 is (Tangential direction) is referred to as the Y direction.
- the direction is defined based on the optical axis and the mapping of the optical disc 10.
- the light beam emitted from the semiconductor laser element 30 of the optical head device will be described.
- the light beam R0 emitted from the semiconductor laser element 30 passes through the hologram element 20 and is condensed on the information recording surface of the optical disk 10 by the collimating lens 11 and the objective lens 12. Reflected light from the optical disk 10 is converted by the objective lens 12 and the collimating lens 11 into light that converges at the light emitting point of the semiconductor laser element 30.
- This light enters the hologram element 20 and is diffracted.
- the diffracted light enters the light receiving element 40, and a signal is detected by the light receiving element 40.
- FIG. 2 is a diagram showing a diffraction region of the hologram element 20 in the present embodiment.
- the grating pattern of the hologram element 20 is divided into a first diffraction region 261 and a second diffraction region 262 by a straight line (region dividing line) L11 that passes through almost the center of the light beam and is parallel to the X axis.
- R0 is the reflected light from the optical disk 10 incident on the hologram element 20.
- R1 and R2 are light diffracted by the optical disc 10, and light and dark according to the tracking position occur in a region that interferes with R0, that is, a region that overlaps.
- region R1 a region where light R0 and light R1 overlap and enter
- region R2 a region where light R0 and light R2 overlap and enter
- region R0 a region where only light R0 enters.
- FIG. 3 is a diagram showing a light receiving region of the light receiving element 40 in the present embodiment.
- the light receiving element 40 has a first light receiving region group 451 and a second light receiving region group 452.
- the first light receiving region group 451 is composed of a first light receiving region 451a and a second light receiving region 451b that are arranged to face each other with a first light receiving dividing line L71 substantially parallel to the X axis interposed therebetween.
- the second light receiving region group 452 includes a third light receiving region 452a and a fourth light receiving region 452b that are arranged to face each other with a second light receiving dividing line L72 substantially parallel to the X axis interposed therebetween.
- the return light from the optical disc 10 straddles the second light-receiving dividing line L72 of the first light-receiving region group 451 to the first light-receiving region 451a and the second light-receiving region 451b in the X direction.
- a grating pattern for converting light having a first wavefront and having the first coma aberration is formed.
- the center of the first coma aberration is at a position shifted in the tangential direction (Y direction) from the center of the optical axis.
- the return light from the optical disc 10 is crossed over the second light receiving division line L72 of the second light receiving region group 452 and is transferred to the third light receiving region 452a and the fourth light receiving region 452b.
- a grating pattern for converting light having a second wavefront and having a second coma aberration opposite to the polarity of the first diffraction region 261 is formed. Similar to the first diffraction region 261, the center of the second coma aberration is at a position shifted from the optical axis center in the tangential direction (Y direction).
- the reason why the second coma aberration having the opposite polarity to that of the first diffraction region 261 is provided is to separate a tracking signal and a focus signal, which will be described later.
- the spot 601 shown in FIG. 3 is diffracted light from the first diffraction region 261, the spot 602 is diffracted light from the second diffraction region 262, and the diffracted light from the region R0, region R1, and region R2 is shown in FIG. The same distinction is used.
- the signal from each light receiving area detects a focus error signal (FE signal) and a tracking error signal (TE signal) by the arithmetic circuit shown in FIG.
- FIG. 5 (a) to 5 (e) are spot diagrams on the light receiving element 40, and FIG. 6 is a diagram showing the obtained focus error signal.
- FIGS. 5 (a) to 5 (e) are spot diagrams with respect to the position of the optical disk 10, and correspond to the positions of FIGS. 6 (a) to 6 (e), respectively.
- the origin is the disc position in the in-focus state (FIG. 5C, FIG. 6C) where the minimum spot is formed on the information recording surface of the optical disc 10.
- FE signal is detected by the circuit shown in FIG. 4 as described above.
- the signal detected by the first light receiving region 451a is the first signal S1
- the signal detected by the second light receiving region 451b is the second signal S2
- the signal detected by the third light receiving region 452a is the third signal.
- Signal S3, a signal detected by the fourth light receiving region 452b is a fourth signal S4
- a sum signal of the first signal S1 and the fourth signal S4 is (S1 + S4)
- the second signal S2 and the second signal S4 When the sum signal of the S3 signal S3 is (S2 + S3), the calculation by this circuit is expressed by the following Equation 4.
- the spot 601 is located at the distance from the first light receiving region 451a to the second light receiving region 451b. Move accordingly. Similarly, the spot 602 moves from the fourth light receiving region 452b to the third light receiving region 452a. As a result, the focus error signal FE expressed by Equation 4 is a negative value.
- the focus error signal FE has a minimum value.
- a spot 601 is generated from the second light receiving region 451b to the first light receiving region 451a. Move according to the distance. Similarly, the spot 602 moves from the third light receiving region 452a to the fourth light receiving region 452b. As a result, the focus error signal FE represented by the above equation 4 has a positive value. When the optical disc 10 and the objective lens 12 are further moved away, most of the spots 601 move to the first light receiving region 451a and most of the spots 602 are moved as shown in FIGS. 5 (e) and 6 (e). The state moves to the fourth light receiving region 452b. In this state, the focus error signal FE has a maximum value.
- the focus error signal FE that changes according to the position of the optical disk 10 can be obtained.
- the distance between the position where the focus error signal FE takes the maximum value and the position where the focus error signal FE takes the minimum value can be designed as desired depending on the amounts of the first and second coma aberrations of the hologram element 20. It is.
- the tracking error signal is and a tracking error signal TE DPD by the tracking error signal TE PP and DPD method using the push-pull method to produce by the following calculation.
- TE PP (S1 + S3) ⁇ (S2 + S4) (Formula 5)
- TE DPD Phase (S1 + S4, S2 + S3) (Formula 6)
- Phase is a function that compares the phases of two signals (calculates a phase difference).
- Equation 5 above represents the differential between the interference region of the light beam R0 and the light beam R1 and the interference region of the light beam R0 and the light beam R2, and it can be seen that a push-pull signal equivalent to the technology according to the prior application can be detected.
- a feature of the optical head device is that light in the region R1 and the region R2 including the tracking signal component is incident on a position away from the first light receiving division line L71 and the second light receiving division line L72. is there. This is realized by shifting the centers of the first and second coma aberrations in the tangential direction (Y direction). Thus, even when the light receiving element 40 is displaced in the radial direction (Y direction), it is possible to realize an optical head device in which the tracking signal component can be clearly separated and is not easily affected by the adjustment error of the light receiving element 40.
- the first embodiment it is possible to detect a tracking error signal having a small influence of a tangential direction (Y direction) shift due to an adjustment error of the light receiving element 40 or the like.
- the present invention is not limited to this, and the centers of the first and second coma aberrations are not limited thereto. May be in a state of being deviated from a straight line passing through the optical axis and extending in the radial direction, that is, a state vector containing a Y-direction component.
- FIG. 7 is a diagram schematically showing the configuration of the optical head device according to the second embodiment of the present invention.
- a semiconductor laser element 30, a light receiving element 40, a hologram element 20, and the like are shown.
- the diffraction grating 24 is formed on the surface of the hologram element 20 on the semiconductor laser element 30 side.
- the semiconductor laser element 30 and the light receiving element 41 are fixed to the holding portion 741 in proximity.
- the holding unit 741 is fixed to the hologram element 20 in a desired positional relationship via another holding unit (not shown).
- the other holding unit may be an optical stage of the optical head device, but a unit (for example, a unit in which the hologram element 20, the semiconductor laser element 30, and the light receiving element 41 are integrated by using a holding member different from the optical stage.
- An optical integrated device may be configured. Such a unit configuration allows a stable optical system.
- the optical head device further includes a collimating lens 11 and an objective lens 12, and constitutes a condensing optical system for condensing the laser light on the optical disk 10 which is an information recording medium.
- the optical head device further includes a lens driving mechanism (not shown) that drives and displaces the objective lens 12 in the optical axis direction (z direction) of the objective lens 12 and the radial direction (x direction) of the optical disk 10.
- a light beam R0 emitted from the semiconductor laser element 30 is diffracted by a diffraction grating 24 at a desired ratio into a main beam (R0a) that is zero-order light and two sub-beams R0b and R0c (not shown) that are ⁇ first-order light.
- R0a main beam
- R0b and R0c sub-beams
- R0b and R0c sub-beams
- This light enters the hologram element 20 and is diffracted.
- the diffracted light enters the light receiving element 41 and a signal is detected by the light receiving element 41.
- the region of the diffraction grating 24 is set to an appropriate size so that the light diffracted by the hologram element 20 is not diffracted.
- the hologram element 20 has the first diffraction region 261 and the second diffraction region 262 shown in FIG. 2 in the same manner as the hologram element described in the first embodiment, and the same grating pattern is formed in each diffraction region. It is.
- the light receiving element 41 has a structure as shown in FIG.
- the light receiving element 41 has a first light receiving region group 451 and a second light receiving region group 452.
- the first light receiving region group 451 includes a first light receiving region 451a and a second light receiving region 451b that are disposed with a first light receiving dividing line L71 substantially parallel to the X axis.
- the second light receiving region group 452 includes a third light receiving region 452a and a fourth light receiving region 452b which are disposed with a second light receiving dividing line L72 substantially parallel to the X axis.
- the light receiving element 41 has a third light receiving region group 453 and a fourth light receiving region group 454 on both sides in the Y direction with the first light receiving region group 451 and the second light receiving region group 452 interposed therebetween.
- the third light receiving region group 453 includes a fifth light receiving region 453a and a sixth light receiving region 453b arranged with a third light receiving dividing line L73 substantially parallel to the X axis.
- the fourth light receiving region group 454 includes a seventh light receiving region 454a and an eighth light receiving region 454b that are disposed with a fourth light receiving dividing line L74 substantially parallel to the X axis.
- the main light beam (R0a) of the return light from the incident optical disk 10 straddles the first light receiving division line L71 of the first light receiving region group 451, and the first light receiving region.
- a lattice pattern is formed on the 451a and the second light receiving region 451b to form the incident spot 601a having the first coma aberration in the x direction.
- the light on the positive side of the X axis in FIG. 2 is detected in the second light receiving region 451b, and the light on the negative side is detected in the second light receiving region 451b. Thereby, a tracking error signal by the push-pull method can be detected.
- the third light receiving region in which the main beam (R0a) of the return light from the incident optical disk 10 straddles the second light receiving dividing line L72 of the second light receiving region group 452 is provided.
- a grating pattern is formed in 452a and the fourth light receiving region 452b to form an incident spot 602a having a second coma aberration opposite to the polarity of the first diffraction region 261.
- the light diffracted in the first diffraction region 261 is incident as a spot 601b and the light diffracted in the second diffraction region 262 is incident as a spot 602b across the third light receiving division line L73.
- the light beam diffracted by the first diffraction region 261 is incident as a spot 601c and the light diffracted by the second diffraction region 262 is incident as a spot 602c across the fourth light receiving dividing line L74.
- the tracking error signal by the push-pull method can be detected from the signals in the two detection areas where each spot is incident.
- the focus error signal is detected by the detection method of the present invention, which will be described later, and the tracking error signal is obtained by using the tracking error signal TE DPD by the DPD method and the tracking error signal TE DPP by the DPP method as follows: Generate by calculation.
- FE (S1 + S4) ⁇ (S2 + S3) (Formula 7)
- TE DPP TE MPP -K ⁇ TE SPP (Formula 8)
- TE DPD phase (S2, S1) -phase (S3, S4) (formula 9)
- the signal detected by the fifth light receiving region 453a is the fifth signal S5
- the signal detected by the sixth light receiving region 453b is the sixth signal S6
- the signal detected by the seventh light receiving region 454a is the seventh signal.
- Signal S7 the signal detected by the eighth light receiving region 454b is the eighth signal S8, the sum signal of the fifth signal S5 and the seventh signal S7 is (S5 + S7), and the sixth signal S6 and the sixth signal S6 If the sum signal of the S8 signal S8 is (S6 + S8), TEMPP is the main beam push-pull signal and TE SPP is the sub-beam push-pull signal, which is given by the following equation.
- TE MPP (S1 + S3)-(S2 + S4) (Formula 10)
- TE SPP (S5 + S7)-(S6 + S8) (Formula 11)
- K is a constant and is optimized so that the fluctuation of TE DPP due to the shift of the objective lens 12 is minimized.
- the optical head device of the present embodiment is also characterized in that the light in the region R1a and the region R2a including the tracking signal component is incident on a position away from the first light receiving division line L71 and the second light receiving division line L72. is there.
- the light beams in the sub-beam region R1b, region R2b, region R1c, and region R2c are also incident on positions separated from the third light receiving dividing line L73 and the fourth light receiving dividing line L74. Accordingly, not only the deviation of the light receiving element 41 in the Y direction but also the deviation of the interval between the sub-beams due to the wavelength deviation of the semiconductor laser element 30 and the deviation of the diffraction grating 24 in the optical axis direction can be allowed.
- the second embodiment it is possible to realize tracking error signal detection in which the influence of the tangential direction (Y direction) shift and the sub-beam interval shift due to the adjustment error of the light receiving element 40 are small.
- the present invention is not limited to this, and the centers of the first and second coma aberrations are not limited thereto. May be in a state of being deviated from a straight line passing through the optical axis and extending in the radial direction, that is, a state vector having a component in the Y direction.
- FIG. 9 is a diagram showing a configuration of the optical information processing apparatus according to the third embodiment of the present invention.
- the optical information processing apparatus includes an optical disc 10, an electric circuit 59, an optical head device 76, a driving device 79, and a rotating mechanism 78.
- the rotation mechanism 78 is a mechanism that holds and rotates the optical disc 10.
- the optical head device 76 is the optical head device described in the first embodiment or the second embodiment, and has fine movement means for the objective lens 12.
- the optical head device 76 is coarsely moved by the driving device 79 to a track where desired information of the optical disk 10 exists. Then, the optical head device 76 sends a signal to the driving device 79.
- the electric circuit 59 has all or part of the arithmetic functions shown in FIG. 4, generates a TE signal and an FE signal, and finely moves the optical head device 76 and the objective lens 12 based on these signals. Sends a signal and performs focus servo and tracking servo.
- the reproduction signal is generated as a sum of signals detected in the light receiving element 40 in the optical head device 76 or in the electric circuit 59, and is output as a raw data signal after signal processing such as an equalizer.
- the tracking error signal can be detected stably even with the optical head device 76 in which the light receiving element 40 is displaced, stable tracking servo can be performed, and good recording and reproduction can be performed. realizable.
- the optical head device As described above, the optical head device, the hologram element, the optical integrated device, the optical information processing apparatus, and the signal detection method according to the present invention have been described based on the first to third embodiments.
- the present invention is not limited to these embodiments. It is not limited. Forms obtained by applying various modifications to these embodiments without departing from the gist of the present invention, and forms realized by arbitrarily combining the components in the respective embodiments are also included in the present invention.
- An optical head device, a hologram element, an optical integrated device, an optical information processing device, and a signal detection method according to the present invention are used for recording / reproducing information on an information storage medium, and as a video / music recording / reproducing device, etc. Useful. It can also be applied to applications such as computer data and program storage and car navigation map data storage.
Abstract
Description
また、DPD法によるトラッキングエラー信号TEDPDとプッシュプル法によるトラッキングエラー信号TEPPは次式の演算により生成する。
TEDPD=Phase(S1+S4、S2+S3) (式3)
ここで、Phaseは二つの信号の位相比較(位相差を算出する)を行う関数である。
まず、本発明の実施の形態1における光ヘッド装置について説明する。
まず、合焦点状態(図5(c)、図6(c))では、第2の信号S2(第2の受光領域451bからの信号)と第1の信号S1(第1の受光領域451aからの信号)、第3の信号S3(第3の受光領域452aからの信号)と第4の信号S4(第4の受光領域452bからの信号)はバランスがとれており、上記式4で表されるフォーカスエラー信号FEは零となる。
TEDPD=Phase(S1+S4、S2+S3) (式6)
ここで、Phaseは二つの信号の位相比較を行う(位相差を算出する)関数である。
次に、本発明の実施の形態2における光ヘッド装置について説明する。
TEDPP=TEMPP-K・TESPP (式8)
TEDPD=phase(S2、S1)-phase(S3、S4)(式9)
ここで、第5の受光領域453aが検出する信号を第5の信号S5、第6の受光領域453bが検出する信号を第6の信号S6、第7の受光領域454aが検出する信号を第7の信号S7、第8の受光領域454bが検出する信号を第8の信号S8とし、第5の信号S5と第7の信号S7との和信号を(S5+S7)とし、第6の信号S6と第8の信号S8との和信号を(S6+S8)とすると、さらに、TEMPPはメインビームのプッシュプル信号、TESPPはサブビームのプッシュプル信号であり、次式で与えられる。
TESPP=(S5+S7)-(S6+S8) (式11)
また、Kは定数で対物レンズ12のシフトによるTEDPPの変動が最小になるように最適化される。
次に、本発明の実施の形態3における光情報処理装置(光ディスク装置)について説明する。
11 コリメートレンズ
12 対物レンズ
20 ホログラム素子
24 回折格子
30 半導体レーザ素子
40 受光素子
41 受光素子
59 電気回路
76 光ヘッド装置
78 回転機構
79 駆動装置
Claims (33)
- 光ビームを出射する光源と、前記光ビームを受け、トラックを有する情報記録媒体上へ微小スポットに収束する集光光学系と、前記情報記録媒体で反射された前記光ビームを回折するホログラム素子と、前記ホログラム素子により回折された光を受光する受光素子とを備えた光ヘッド装置であって、
前記受光素子は、少なくとも
第1の信号S1を検出する第1の受光領域と、
第2の信号S2を検出する第2の受光領域と、
第3の信号S3を検出する第3の受光領域と、
第4の信号S4を検出する第4の受光領域とを有し、
前記第1の受光領域と前記第2の受光領域は、第1の受光分割線を挟んで対向して配置されており、
前記第3の受光領域と前記第4の受光領域は、第2の受光分割線を挟んで対向して配置されており、
前記ホログラム素子は、第1の回折領域と第2の回折領域とを有し、
前記第1の回折領域と前記第2の回折領域は、前記集光光学系の光軸中心を通り、前記情報記録媒体のラジアル方向に延びる領域分割線を挟んで配置されており、
前記第1の回折領域には、第1の前記受光領域と前記第2の受光領域に入射する第1の波面を持つ回折光を発生させる格子パターンが形成され、
前記第2の回折領域には、第3の前記受光領域と前記第4の受光領域に入射する第2の波面を持つ回折光を発生させる格子パターンが形成され、
前記第1の波面は、前記情報記録媒体のラジアル方向の第1のコマ収差を持ち、前記第1のコマ収差の軸は、前記集光光学系の光軸中心より離間しており、
前記第2の波面は、前記情報記録媒体のラジアル方向の第2のコマ収差を持ち、前記第2のコマ収差の軸は、前記集光光学系の光軸中心より離間している光ヘッド装置。 - さらに、
前記第1の信号S1と前記第2の信号S2の差信号(S1-S2)、もしくは前記第3の信号S3と前記第4の信号S4の差信号(S3-S4)、もしくはその両方によりフォーカスエラー信号FEを検出する回路を備える請求項1記載の光ヘッド装置。 - 前記第1のコマ収差と前記第2のコマ収差の極性が逆である請求項2記載の光ヘッド装置。
- さらに、
前記第1の信号S1と前記第4の信号S4との和信号を(S1+S4)とし、前記第2の信号S2と前記第3の信号S3との和信号を(S2+S3)としたときに、
(S1+S4)-(S2+S3)の演算によりフォーカスエラー信号を検出する回路を備える請求項3記載の光ヘッド装置。 - さらに、
前記第1の信号S1と前記第3の信号S3との和信号を(S1+S3)とし、前記第2の信号S2と前記第4の信号S4との和信号を(S2+S4)としたときに、
(S1+S3)-(S2+S4)の演算によりプッシュプル信号を検出する回路を備える請求項1記載の光ヘッド装置。 - さらに、
前記第1の信号S1と前記第4の信号S4との和信号を(S1+S4)とし、前記第2の信号S2と前記第3の信号S3との和信号を(S2+S3)としたときに、
(S1+S4)と(S2+S3)の位相差信号を検出する回路を備える請求項1記載の光ヘッド装置。 - さらに、
前記光源から出射された前記光ビームからメインビームと第1のサブビームと第2のサブビームを生成する回折格子を有し、
前記受光素子は、さらに、
第5の信号S5を検出する第5の受光領域と、
第6の信号S6を検出する第6の受光領域と、
第7の信号S7を検出する第7の受光領域と、
第8の信号S8を検出する第8の受光領域とを有し、
前記第5の受光領域と前記第6の受光領域は、第3の受光分割線を挟んで対向して配置されており、
前記第7の受光領域と前記第8の受光領域は、第4の受光分割線を挟んで対向して配置されている請求項1記載の光ヘッド装置。 - さらに、
Kを定数とし、前記第1の信号S1と前記第3の信号S3との和信号を(S1+S3)とし、前記第2の信号S2と前記第4の信号S4との和信号を(S2+S4)とし、前記第5の信号S5と前記第7の信号S7との和信号を(S5+S7)とし、前記第6の信号S6と前記第8の信号S8との和信号を(S6+S8)としたときに、
{(S1+S3)-(S2+S4)}-K{(S5+S7)-(S6+S8)}
の演算により差動プッシュプル信号を検出する回路を備える請求項7記載の光ヘッド装置。 - 光を回折する回折素子として機能するホログラム素子であって、
第1の回折領域と第2の回折領域とを有し、前記第1の回折領域と前記第2の回折領域は、領域分割線を挟んで配置されており、
前記第1の回折領域は、前記領域分割線方向の第1のコマ収差を持つ回折光を生成し、
前記第2の回折領域は、前記領域分割線方向の第2のコマ収差を持つ回折光を生成し、
前記第1のコマ収差の軸は、前記領域分割線より離間しており、
前記第2のコマ収差の軸は、前記領域分割線より離間しているホログラム素子。 - 前記第1のコマ収差と前記第2のコマ収差の極性が逆である請求項9記載のホログラム素子。
- 光ビームを出射する光源と、情報記録媒体で反射された前記光ビームを回折するホログラム素子と、前記ホログラム素子により回折された光を受光する受光素子とを備えた光集積素子であって、
前記受光素子は、少なくとも
第1の信号S1を検出する第1の受光領域と、
第2の信号S2を検出する第2の受光領域と、
第3の信号S3を検出する第3の受光領域と、
第4の信号S4を検出する第4の受光領域とを有し、
前記第1の受光領域と前記第2の受光領域は、第1の受光分割線を挟んで対向して配置されており、
前記第3の受光領域と前記第4の受光領域は、第2の受光分割線を挟んで対向して配置されており、
前記ホログラム素子は、第1の回折領域と第2の回折領域とを有し、
前記第1の回折領域と前記第2の回折領域は、前記集光光学系の光軸中心を通り、前記情報記録媒体のラジアル方向に延びる領域分割線を挟んで配置されており、
前記第1の回折領域には、第1の前記受光領域と前記第2の受光領域に入射する第1の波面を持つ回折光を発生させる格子パターンが形成され、
前記第2の回折領域には、第3の前記受光領域と前記第4の受光領域に入射する第2の波面を持つ回折光を発生させる格子パターンが形成され、
前記第1の波面は、前記情報記録媒体のラジアル方向の第1のコマ収差を持ち、前記第1のコマ収差の軸は、前記集光光学系の光軸中心より離間しており、
前記第2の波面は、前記情報記録媒体のラジアル方向の第2のコマ収差を持ち、前記第2のコマ収差の軸は、前記集光光学系の光軸中心より離間している光集積素子。 - さらに、
前記第1の信号S1と前記第2の信号S2の差信号(S1-S2)、もしくは前記第3の信号S3と前記第4の信号S4の差信号(S3-S4)、もしくはその両方によりフォーカスエラー信号FEを検出する回路を備える請求項11記載の光集積素子。 - 前記第1のコマ収差と前記第2のコマ収差の極性が逆である請求項12記載の光集積素子。
- さらに、
前記第1の信号S1と前記第4の信号S4との和信号を(S1+S4)とし、前記第2の信号S2と前記第3の信号S3との和信号を(S2+S3)としたときに、
(S1+S4)-(S2+S3)の演算によりフォーカスエラー信号を検出する回路を備える請求項13記載の光集積素子。 - さらに、
前記第1の信号S1と前記第3の信号S3との和信号を(S1+S3)とし、前記第2の信号S2と前記第4の信号S4との和信号を(S2+S4)としたときに、
(S1+S3)-(S2+S4)の演算によりプッシュプル信号を検出する回路を備える請求項11記載の光集積素子。 - 前記第1の信号S1と前記第4の信号S4との和信号を(S1+S4)とし、前記第2の信号S2と前記第3の信号S3との和信号を(S2+S3)としたときに、
(S1+S4)と(S2+S3)の位相差信号を検出する回路を備える請求項11記載の光集積素子。 - さらに、
前記光源から出射された前記光ビームからメインビームと第1のサブビームと第2のサブビームを生成する回折格子を有し、
前記受光素子は、さらに、
第5の信号S5を検出する第5の受光領域と、
第6の信号S6を検出する第6の受光領域と、
第7の信号S7を検出する第7の受光領域と、
第8の信号S8を検出する第8の受光領域とを有し、
前記第5の受光領域と前記第6の受光領域は、第3の受光分割線を挟んで対向して配置されており、
前記第7の受光領域と前記第8の受光領域は、第4の受光分割線を挟んで対向して配置されている請求項11記載の光集積素子。 - さらに、
Kを定数とし、前記第1の信号S1と前記第3の信号S3との和信号を(S1+S3)とし、前記第2の信号S2と前記第4の信号S4との和信号を(S2+S4)とし、前記第5の信号S5と前記第7の信号S7との和信号を(S5+S7)とし、前記第6の信号S6と前記第8の信号S8との和信号を(S6+S8)としたときに、
{(S1+S3)-(S2+S4)}-K{(S5+S7)-(S6+S8)}
の演算により差動プッシュプル信号を検出する回路を備える請求項17記載の光集積素子。 - 光ビームを出射する光源と、前記光ビームを受け、トラックを有する情報記録媒体上へ微小スポットに収束する集光光学系と、前記情報記録媒体で反射された前記光ビームを回折するホログラム素子と、前記ホログラム素子により回折された光を受光する受光素子とを備えた光ヘッド装置における信号検出方法であって、
前記受光素子は、少なくとも
第1の信号S1を検出する第1の受光領域と、
第2の信号S2を検出する第2の受光領域と、
第3の信号S3を検出する第3の受光領域と、
第4の信号S4を検出する第4の受光領域とを有し、
前記第1の受光領域と前記第2の受光領域は、第1の受光分割線を挟んで対向して配置されており、
前記第3の受光領域と前記第4の受光領域は、第2の受光分割線を挟んで対向して配置されており、
前記ホログラム素子は、第1の回折領域と第2の回折領域とを有し、
前記第1の回折領域と前記第2の回折領域は、前記集光光学系の光軸中心を通り、前記情報記録媒体のラジアル方向に延びる領域分割線を挟んで配置されており、
前記信号検出方法は、
前記第1の回折領域で、第1の前記受光領域と前記第2の受光領域に入射する第1の波面を持つ回折光を発生させ、
前記第2の回折領域で、第3の前記受光領域と前記第4の受光領域に入射する第2の波面を持つ回折光を発生させ、
前記第1の波面は、前記情報記録媒体のラジアル方向の第1のコマ収差を持ち、前記第1のコマ収差の軸は、前記集光光学系の光軸中心より離間しており、
前記第2の波面は、前記情報記録媒体のラジアル方向の第2のコマ収差を持ち、前記第2のコマ収差の軸は、前記集光光学系の光軸中心より離間している信号検出方法。 - 前記第1の信号S1と前記第2の信号S2の差信号(S1-S2)、もしくは前記第3の信号S3と前記第4の信号S4の差信号(S3-S4)、もしくはその両方によりフォーカスエラー信号FEを検出する請求項19記載の信号検出方法。
- 前記第1のコマ収差と前記第2のコマ収差の極性が逆である請求項20記載の信号検出方法。
- さらに、
前記第1の信号S1と前記第4の信号S4との和信号を(S1+S4)とし、前記第2の信号S2と前記第3の信号S3との和信号を(S2+S3)としたときに、
(S1+S4)-(S2+S3)の演算によりフォーカスエラー信号を検出する請求項21記載の信号検出方法。 - さらに、
前記第1の信号S1と前記第3の信号S3との和信号を(S1+S3)とし、前記第2の信号S2と前記第4の信号S4との和信号を(S2+S4)としたときに、
(S1+S3)-(S2+S4)の演算によりプッシュプル信号を検出する請求項19記載の信号検出方法。 - さらに、
前記第1の信号S1と前記第4の信号S4との和信号を(S1+S4)とし、前記第2の信号S2と前記第3の信号S3との和信号を(S2+S3)としたときに、
(S1+S4)と(S2+S3)の位相差信号を検出する請求項19記載の信号検出方法。 - 前記光ヘッド装置は、さらに、前記光源から出射された前記光ビームからメインビームと第1のサブビームと第2のサブビームを生成する回折格子を有し、
前記受光素子は、さらに、
第5の信号S5を検出する第5の受光領域と、
第6の信号S6を検出する第6の受光領域と、
第7の信号S7を検出する第7の受光領域と、
第8の信号S8を検出する第8の受光領域とを有し、
前記第5の受光領域と前記第6の受光領域は、第3の受光分割線を挟んで対向して配置されており、
前記第7の受光領域と前記第8の受光領域は、第4の受光分割線を挟んで対向して配置されている請求項19記載の信号検出方法。 - さらに、
Kを定数とし、前記第1の信号S1と前記第3の信号S3との和信号を(S1+S3)とし、前記第2の信号S2と前記第4の信号S4との和信号を(S2+S4)とし、前記第5の信号S5と前記第7の信号S7との和信号を(S5+S7)とし、前記第6の信号S6と前記第8の信号S8との和信号を(S6+S8)としたときに、
{(S1+S3)-(S2+S4)}-K{(S5+S7)-(S6+S8)}
の演算により差動プッシュプル信号を検出する請求項25記載の信号検出方法。 - 請求項1記載の光ヘッド装置を有する光情報処理装置であって、
前記第1の信号S1と前記第2の信号S2の差信号(S1-S2)、もしくは前記第3の信号S3と前記第4の信号S4の差信号(S3-S4)、もしくはその両方により生成されたフォーカスエラー信号によりフォーカスサーボを行う回路を備える光情報処理装置。 - 前記第1のコマ収差と前記第2のコマ収差の極性が逆である請求項27記載の光情報処理装置。
- さらに、
前記第1の信号S1と前記第4の信号S4との和信号を(S1+S4)とし、前記第2の信号S2と前記第3の信号S3との和信号を(S2+S3)としたときに、
(S1+S4)-(S2+S3)の演算によりフォーカスエラー信号を検出する回路を備える請求項28記載の光情報処理装置。 - さらに、
前記第1の信号S1と前記第3の信号S3との和信号を(S1+S3)とし、前記第2の信号S2と前記第4の信号S4との和信号を(S2+S4)としたときに、
(S1+S3)-(S2+S4)の演算によりプッシュプル信号を検出する回路を備える請求項27記載の光情報処理装置。 - さらに、
前記第1の信号S1と前記第4の信号S4との和信号を(S1+S4)とし、前記第2の信号S2と前記第3の信号S3との和信号を(S2+S3)としたときに、
(S1+S4)と(S2+S3)の位相差信号を検出する回路を備える請求項27記載の光情報処理装置。 - さらに、
前記光源から出射された前記光ビームからメインビームと第1のサブビームと第2のサブビームを生成する回折格子を有し、
前記受光素子は、さらに、
第5の信号S5を検出する第5の受光領域と、
第6の信号S6を検出する第6の受光領域と、
第7の信号S7を検出する第7の受光領域と、
第8の信号S8を検出する第8の受光領域とを有し、
前記第5の受光領域と前記第6の受光領域は、第3の受光分割線を挟んで対向して配置されており、
前記第7の受光領域と前記第8の受光領域は、第4の受光分割線を挟んで対向して配置されている請求項27記載の光情報処理装置。 - さらに、
Kを定数とし、前記第1の信号S1と前記第3の信号S3との和信号を(S1+S3)とし、前記第2の信号S2と前記第4の信号S4との和信号を(S2+S4)とし、前記第5の信号S5と前記第7の信号S7との和信号を(S5+S7)とし、前記第6の信号S6と前記第8の信号S8との和信号を(S6+S8)としたときに、
{(S1+S3)-(S2+S4)}-K{(S5+S7)-(S6+S8)}
の演算により差動プッシュプル信号を検出する回路を備える請求項32記載の光情報処理装置。
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Publication number | Priority date | Publication date | Assignee | Title |
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JPH033122A (ja) * | 1989-05-31 | 1991-01-09 | Toshiba Corp | 焦点検出装置 |
JPH0845127A (ja) * | 1994-07-29 | 1996-02-16 | Olympus Optical Co Ltd | 光ヘッド |
JP2001229573A (ja) | 1999-12-10 | 2001-08-24 | Victor Co Of Japan Ltd | 光ピックアップ |
JP2007018683A (ja) * | 2005-06-10 | 2007-01-25 | Sharp Corp | 光ピックアップ |
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US5541996A (en) * | 1994-12-12 | 1996-07-30 | Itt Corporation | Apparatus and method for a pseudo-random number generator for high precision numbers |
FR2779932B1 (fr) * | 1998-06-18 | 2000-12-01 | Taema | Dispositif de determination de phases respiratoires du sommeil d'un utilisateur |
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Publication number | Priority date | Publication date | Assignee | Title |
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JPH033122A (ja) * | 1989-05-31 | 1991-01-09 | Toshiba Corp | 焦点検出装置 |
JPH0845127A (ja) * | 1994-07-29 | 1996-02-16 | Olympus Optical Co Ltd | 光ヘッド |
JP2001229573A (ja) | 1999-12-10 | 2001-08-24 | Victor Co Of Japan Ltd | 光ピックアップ |
JP2007018683A (ja) * | 2005-06-10 | 2007-01-25 | Sharp Corp | 光ピックアップ |
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