WO2004100139A1 - 光ヘッド装置、その製造方法及び光学式情報記録再生装置 - Google Patents
光ヘッド装置、その製造方法及び光学式情報記録再生装置 Download PDFInfo
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- WO2004100139A1 WO2004100139A1 PCT/JP2004/006333 JP2004006333W WO2004100139A1 WO 2004100139 A1 WO2004100139 A1 WO 2004100139A1 JP 2004006333 W JP2004006333 W JP 2004006333W WO 2004100139 A1 WO2004100139 A1 WO 2004100139A1
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- aberration
- optical element
- optical
- correcting
- height
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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
- G11B7/1365—Separate or integrated refractive elements, e.g. wave plates
- G11B7/1367—Stepped phase plates
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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
- G11B7/1392—Means for controlling the beam wavefront, e.g. for correction of aberration
- G11B7/13922—Means for controlling the beam wavefront, e.g. for correction of aberration passive
Definitions
- Optical head device manufacturing method thereof, and optical information recording / reproducing device
- the present invention relates to an optical head apparatus for performing recording, recording, and reproduction on an optical recording medium, a method for manufacturing the same, and an optical information recording / reproducing apparatus.
- the present invention relates to an optical head device capable of easily correcting various aberrations generated in an optical system of a head device, a manufacturing method thereof, and an optical information recording / reproducing device incorporating the optical head device.
- the recording density of an optical information recording / reproducing device is inversely proportional to the square of the diameter of a converging spot formed on an optical recording medium by an optical head device. That is, the smaller the diameter of the focusing spot, the higher the recording density.
- the diameter of the focusing spot is proportional to the wavelength of the light source in the optical head device, and inversely proportional to the numerical aperture of the objective lens. That is, the shorter the wavelength of the light source and the higher the numerical aperture of the objective lens, the smaller the diameter of the focused spot.
- various aberrations such as coma, spherical aberration, astigmatism, and arrow-shaped aberration occur due to manufacturing errors and adjustment errors of optical components.
- coma and astigmatism occur, and if the distance between the entrance surface and the exit surface of the objective lens deviates from the design, spherical aberration occurs.
- the shape of the condensing spot is disturbed, and the recording / reproducing characteristics deteriorate.
- the magnitudes of coma, spherical aberration, and astigmatism are inversely proportional to the wavelength of the light source, and are proportional to the cube of the numerical aperture of the objective lens, respectively. Because of this, the light source The shorter the wavelength and the higher the numerical aperture of the objective lens, the narrower the margin of various aberrations with respect to the recording and reproducing characteristics. Therefore, in an optical head device and an optical information recording / reproducing device in which the wavelength of the light source is shortened in order to increase the recording density and the numerical aperture of the objective lens is increased, in order to prevent the recording / reproducing characteristics from deteriorating, the light It is necessary to correct various aberrations that occur in the optical system of the storage device.
- FIG. 14 is a block diagram showing an optical head device in which a liquid crystal optical element is provided in a conventional optical system.
- a semiconductor laser 1 is provided, and the semiconductor laser 1 is emitted from the semiconductor laser 1 along the path of the laser light emitted by the semiconductor laser 1.
- Objective lens that converges the incident parallel light.
- the objective lens 6 is provided with a disk 7 as an optical recording medium at the focal point.
- a cylindrical lens 8, a lens 9, and a photodetector 10 are arranged along a path of light reflected by the polarization beam splitter 3.
- the photodetector 10 is provided between two focal lines formed by the compound lens including the cylindrical lens 8 and the lens 9.
- a semiconductor laser 1 as a light source emits a laser beam, and this laser beam is collimated by a collimator lens 2 and is incident on a polarization beam splitter 3 as P-polarized light.
- a polarization beam splitter 3 As P-polarized light.
- the liquid crystal optical element 18 Through the liquid crystal optical element 18, through the 1/4 wavelength plate 5, and from linearly polarized light. The light is converted into circularly polarized light, and is condensed by an objective lens 6 on a disk 7 as an optical recording medium. Then, the light is reflected on the disk 7.
- the reflected light from the disc 7 passes through the objective lens 6 in the opposite direction, passes through the 1Z4 wavelength plate 5, and is converted from circularly polarized light into linearly polarized light whose polarization direction is orthogonal to the outward path, and the liquid crystal optical element 18 is reversed.
- the light is incident on the polarizing beam splitter 3 as S-polarized light, is almost completely reflected, is transmitted through the cylindrical lens 8 and the lens 9, is given astigmatism, and is received by the photodetector 10.
- FIGS. 15 (a) to 15 (c) are plan views showing a liquid crystal optical element
- FIG. 15 (a) shows a liquid crystal optical element 18a for correcting coma
- FIG. 15 (b) shows a liquid crystal optical element for correcting spherical aberration.
- An element 18b is shown
- (c) shows a liquid crystal optical element 18c for correcting astigmatism.
- the configuration of the liquid crystal optical elements 18a, 18b, and 18c is described in, for example, the above-mentioned reference (Optakes Design No. 21, page 50 to page 55).
- the broken line in the figure corresponds to the effective area of the objective lens 6.
- the liquid crystal optical elements 18a to 18c control the phase distribution of incident light by controlling the voltage applied to each region, thereby controlling the refractive index of each region.
- the liquid crystal optical element 18a is divided into five regions of regions 19a to 19e.
- a first voltage V1 is applied to the areas 19b and 19e
- a second voltage V2 is applied to the area 19a
- a third voltage V3 is applied to the areas 19c and 19d.
- the voltage V is changed, the coma aberration with respect to the transmitted light changes. Therefore, by adjusting the voltage V, a coma aberration that cancels the coma generated in the optical system is generated in the liquid crystal optical element 18a, and the coma aberration is corrected. Further, as shown in FIG.
- the liquid crystal optical element 18b is divided into five regions of regions 19f to 19j.
- the first voltage V 1 is applied to the region 19 h
- the second voltage V 2 is applied to the region 19 g and 19 i
- the region 19 is applied.
- ⁇ ⁇ Apply the third voltage V 3 to 19 j.
- the voltage V is changed, the spherical aberration with respect to the transmitted light changes. Therefore, by adjusting the voltage V, a spherical aberration that cancels out the spherical aberration generated in the optical system is generated in the liquid crystal optical element 18b, and the spherical aberration is corrected.
- the liquid crystal optical element 18c is divided into five regions of regions 19k to 19o.
- the first voltage VI is applied to the areas 191 and 19 m
- the second voltage V2 is applied to the area 19k
- the third voltage V3 is applied to the areas 19n and 19o.
- the astigmatism with respect to the transmitted light changes. Therefore, by adjusting the voltage V, astigmatism that cancels out the astigmatism generated in the optical system is generated in the liquid crystal optical element 18c, and the astigmatism is corrected.
- a head device incorporating an aberration correction device other than the liquid crystal optical element has also been developed.
- a head device incorporating an aberration correction device including a plurality of optical elements and movable means for controlling a relative position between the plurality of optical elements is disclosed (see, for example, Japanese Patent Application Laid-Open No. 2000-2000). — See 1 13494 and Special Publication 2001-0443549.
- a movable unit controls the relative positional relationship of a plurality of optical elements in accordance with the aberration generated in the optical system of the head device, so that the aberration correcting device can be used.
- the aberration can be controlled so as to cancel the aberration of the head device.
- an aberration correction element which has been adjusted so as to cancel the aberration of the optical system of the head device, is incorporated in the head device (for example, refer to Japanese Patent Application Laid-Open No. 2003-006909).
- the above-described conventional technology has the following problems.
- a drive circuit (not shown) for applying a voltage to each area of the liquid crystal optical element 18 is required.
- a control circuit (not shown) for controlling the driving circuit is required. Therefore, the configuration of the optical information recording / reproducing apparatus using the present optical head apparatus becomes extremely complicated, and the cost increases and the size increases.
- a head device incorporating an aberration correction device having a plurality of optical elements and movable means also requires a circuit for operating the movable means, which complicates the configuration of the optical information recording / reproducing device.
- An object of the present invention is to solve the above-mentioned problems in the conventional optical head device and the optical information recording / reproducing device, and to eliminate the need for a special drive circuit and control circuit, and to provide an optical head device with an optical device. It is an object of the present invention to provide an optical head device, a method of manufacturing the same, and an optical information recording / reproducing device capable of easily correcting various aberrations occurring in a system at low cost.
- An optical head device includes: a light source; an objective lens for condensing light emitted from the light source on an optical recording medium; a light detector for detecting light reflected by the optical recording medium; Via the light path from the light source to the objective lens 6 06333
- one or more aberration-correcting optical elements for correcting aberrations of the light generated in this path, wherein the one or more aberration-correcting optical elements include a plurality of types of aberration-correcting optics. It is characterized in that it is selected from the elements according to the aberration.
- various aberrations occurring in this light path are corrected by an aberration correcting optical element provided so as to be interposed in the light path.
- the aberration correction optical element is selected from a plurality of types of aberration correction optical elements prepared in advance in accordance with the aberration, so that the aberration can be corrected with high accuracy. No drive circuit is required to drive the elements.
- control circuit for controlling the driving circuit is not required. Further, there is no need to manufacture an aberration correction optical element that is optimally adjusted for each head device. Therefore, various aberrations can be easily corrected at low cost without complicating the configuration of the optical information recording / reproducing apparatus incorporating the optical head device.
- the plurality of types of aberration correction optical elements have different types, signs, or correction amounts of aberration to be corrected.
- the aberration can be corrected in many cases.
- At least one of the surfaces of the aberration correction optical element on which the light enters or exits may have a stepped shape having two or more levels of steps. Thereby, an aberration correction optical element can be easily manufactured.
- At least one of the surfaces of the aberration correction optical element on which the light enters or exits may be formed by a curved surface. Thereby, aberration can be corrected with high accuracy.
- the method for manufacturing an optical head device includes: a light source; Assembling an optical system including an objective lens for condensing light on an optical recording medium, and a photodetector for detecting light reflected by the optical recording medium; from the light source to the objective lens in the optical system Measuring the aberration generated in the light path of the above, and correcting one or more aberrations of the light from among a plurality of types of aberration correcting optical elements based on the measurement result of the aberration. Selecting a correction optical element and incorporating the correction optical element into the optical system so as to be interposed in the light path.
- An optical information recording / reproducing apparatus includes: the optical head device; a first circuit for driving the light source; and a second circuit for generating a reproduced signal and an error signal based on an output signal of the photodetector. And a third circuit for controlling the position of the objective lens based on the error signal.
- one or a plurality of aberration correcting optical elements selected according to the aberration are incorporated from among a plurality of types of aberration correcting optical elements, thereby producing an optical system of an optical head device.
- Various aberrations can be easily corrected without the need for special drive and control circuits. This makes it possible to reduce the cost and size of the optical information recording / reproducing apparatus.
- FIG. 1 is a block diagram showing an optical information recording / reproducing apparatus according to the first embodiment of the present invention.
- FIG. 2A is a plan view showing an aberration correcting optical element 4a for correcting coma aberration in the present embodiment, and FIGS. 2B to 2E are shown in FIG. 2A. It is sectional drawing by A-A 'line.
- FIG. 3A is a plan view showing an aberration correcting optical element 4b for correcting spherical aberration in the present embodiment, and FIGS. 3B to 3E are shown in FIG. 3A. It is sectional drawing by the BB line.
- FIG. 4A is a plan view showing an aberration correcting optical element 4c for correcting astigmatism in the present embodiment, and FIGS. 4B to 4E are shown in FIG. 4A.
- C is a cross-sectional view taken along line C-C.
- FIG. 5A is a plan view showing an aberration correcting optical element 4d for correcting an arrow-shaped aberration in the present embodiment, and FIGS. 5B to 5E are shown in FIG. 5A. It is sectional drawing by the D-D 'line.
- FIG. 6 is a graph showing a wavefront aberration of an optical element 4a.
- FIG. 9 is a graph showing a wavefront aberration of an optical element 4b.
- FIG. 9 is a graph showing a wavefront aberration of an optical element 4c.
- FIG. 9 is a graph showing a wavefront aberration of an optical element 4d.
- FIG. 10 (a) is a plan view showing an aberration correction optical element 4e for capturing coma aberration according to the second embodiment of the present invention
- FIGS. 10 (b) to 10 (e) are FIG. 10 is a cross-sectional view taken along line EE shown in FIG. 10 (a).
- FIG. 11A is a plan view showing the aberration correcting optical element 4f for correcting spherical aberration in the present embodiment
- FIGS. 11B to 11E are FIGS. 11A to 11E. It is sectional drawing by the FF, line shown in FIG.
- FIG. 12A is a plan view showing an aberration correcting optical element 4 g for correcting astigmatism in the present embodiment, and FIGS. 12B to 12E are FIGS. )
- FIG. 3 is a sectional view taken along line GG ′ shown in FIG.
- FIG. 13 (a) is a plan view showing an aberration correcting optical element 4h for correcting an arrow-shaped aberration according to the present embodiment
- FIGS. 13 (b) to 13 (e) show FIGS. ) Is a cross-sectional view taken along the line HH, shown in FIG.
- FIG. 14 is a block diagram showing an optical head device in which a liquid crystal optical element is provided in a conventional optical system.
- FIGS. 15 (a) to 15 (c) are plan views showing a liquid crystal optical element.
- FIG. 15 (a) shows a liquid crystal optical element 18a for correcting coma aberration
- FIGS. ) Shows a liquid crystal optical element 18b for correcting spherical aberration
- FIG. 15 (c) shows a liquid crystal optical element 18c for correcting astigmatism.
- FIG. 1 is a block diagram showing an optical information recording / reproducing apparatus according to the present embodiment
- FIG. 2 (a), FIG. 2 (e), FIG. 3 (a) to FIG. 3 (e), FIG. ) To 4 (e) and FIGS. 5 (a) to 5 (e) are diagrams showing aberration correction optical elements incorporated in the optical head device of the optical information recording / reproducing apparatus. It is a top view, and (b) thru / or (e) of each figure are sectional views.
- the optical information recording / reproducing device is, for example, a DVD (Digital Versatile Disc) drive. As shown in FIG. 1, the optical information recording / reproducing device according to the present embodiment incorporates an optical head device 21.
- the optical head device 21 is provided with a semiconductor laser 1, and a collimator that converts the laser light emitted from the semiconductor laser 1 into parallel light along a path of the laser light emitted from the semiconductor laser 1.
- Lens 2 a polarizing beam splitter 3, which transmits P-polarized light and reflects S-polarized light in a predetermined direction, an aberration correction optical element 4, which corrects the aberration of the optical system,
- a 1/4 wavelength plate 5 that gives a phase difference of 1/4 wavelength between them and an objective lens 6 that converges the incident parallel light are provided.
- the disc 7 as an optical recording medium is positioned at the focal point of the objective lens 6.
- a cylindrical lens 8, a lens 9 and a photodetector 10 are arranged along the path of the light reflected by the polarization beam splitter 3.
- the cylindrical lens 8 and the lens 9 constitute a compound lens that gives astigmatism to light.
- the photodetector 10 is provided between two focal lines formed by a composite lens including the cylindrical lens 8 and the lens 9.
- a plurality of light receiving portions (not shown) are arranged on a light receiving surface of the light, and the intensity of the light received by each of the light receiving portions is measured to determine the intensity of the incident light. It detects various signals.
- an optical head device 21 in the optical information recording / reproducing apparatus is provided outside the optical head device 21 for driving the semiconductor laser 1 based on recording data input from the outside.
- a recording signal generation circuit 12 for generating the recording signal of the above is provided. Further, the recording signal output from the recording signal generating circuit 12 is input, a driving signal for driving the semiconductor laser 1 is generated based on the recording signal, and the driving signal is output to the semiconductor laser 1.
- a drive circuit 13 is provided.
- a preamplifier 14 for converting a current signal output from the photodetector 10 into a voltage signal is provided. Based on the voltage signal output from the preamplifier 14, a reproduction signal is generated and reproduced. A reproduction signal generation circuit 15 for outputting data to the outside is provided. An error signal generation circuit 16 for generating a focus error signal and a track error signal for driving the objective lens 6 based on the voltage signal output from the preamplifier 14 is provided. Track error signals are input and these signals An objective lens driving circuit 17 that generates a driving signal based on the objective lens driving circuit 17 is provided, and an actuator that receives the driving signal output from the objective lens driving circuit 17 and controls the position of the objective lens 6 (not shown) ) Are provided. Further, in the optical information recording / reproducing apparatus according to the present embodiment, a spindle control circuit for rotating the disk 7, a positioner control circuit for moving the entire optical head device 21 with respect to the disk 7, and the like are provided. ing.
- the aberration correcting optical element 4 is interposed in the light path from the semiconductor laser 1 to the objective lens 6. In FIG. 1, it is inserted between the polarizing beam splitter 3 and the 1Z 4-wavelength plate 5, but may be inserted anywhere in the optical system from the semiconductor laser 1 to the objective lens 6. .
- the aberration correction optical element 4 is one or more aberration correction optical elements selected from a plurality of aberration correction optical elements described below, and is included in the optical head device 21.
- the aberration correction optical element that can most effectively correct the generated aberration is selected and incorporated into the optical head device 21.
- a plurality of aberration correcting optical elements serving as the aberration correcting optical elements 4 incorporated in the optical head device 21 will be described in detail.
- the aberration correcting optical element 4a shown in FIG. FIG. 2A is a plan view showing the aberration correction optical element 4a. As shown in FIG. 2 (a), the aberration correction optical element 4a is divided into five areas 11a to 11e. The broken line in the figure indicates the effective area of the objective lens 6.
- a region 11a composed of a convex curve whose outer edge swells in the + X direction and the -X direction, and both ends in the Y direction of this region 11a are provided. However, they protrude outside the effective area of the objective lens 6 and are in contact with the edges of the difference correction optical element 4a, respectively. Further, both sides of the region 11a in the X direction are regions 11d and 11e, respectively. Furthermore, region 1 1a Mutually symmetrical and ing position, the two regions 1 1 b and 1 1 c is provided with respect to a center line parallel to the Y axis area 1 1 a inside.
- FIGS. 2 (b) to 2 (e) show four types of aberration correcting optical elements 4 ai to 4 a 4 having different coma aberration correction amounts and / or signs, respectively. It is sectional drawing by a line. As shown in FIG. 2 (b) to (e), the surface shape of the aberration correcting optical element 4 ai ⁇ 4 a 4 is a three-level stepped.
- the height of the regions lib and lie is higher by h than the height of the regions 11 a and the heights of the regions 11 c and 11 d are higher. The height is h lower than the height of the area 11a.
- FIG. 2 (c) yield difference shown in correcting optical element 4 a 2 the height of the region 1 1 b and 1 1 e is only 2 h higher than the height of the region 1 1 a, region 1 1 c and The height of 1 d is 2 h lower than the height of region 11 a.
- region 1 1 b height ⁇ Pi 1 1 e is h only lower than the height of the region 1 1 a, region 1 1 c and The height of 11 d is higher than the height of region 11 a by h.
- areas lib height ⁇ Pi 1 1 e is only 2 h than the height of the region 1 1 a lower region 1 1 c and 1 1
- the height of d is 2 h higher than the height of region 11a.
- the cross section in the Y direction passing through the center of the aberration correcting optical element 4a is flat.
- the aberration correction optical element 4a having such a cross section can be manufactured by molding glass or plastic, or by depositing a dielectric on glass.
- the latter manufacturing method is low in manufacturing cost because photolithography processes can be applied, and remains mass-producible.
- FIG. 6 is a plan view showing an element 4b. As shown in FIG. 3 (a), the aberration correction optical element 4b is divided into five areas 11f to 11j. The broken line in the figure indicates the effective area of the objective lens 6.
- a circular area 11f whose center coincides with the center of the aberration correcting optical element 4b.
- An annular area 11g, 11h and 11i are provided concentrically with the area 11f, and an area 11j outside the area 11i in the aberration correcting optical element 4b is provided. I have.
- the outer edge of the area 11 i is located inside the area corresponding to the effective area of the objective lens 6.
- the aberration correction optical elements 4 b can be further classified into four types of aberration correction optical elements 4 bi to 4 b 4 depending on the correction amount of spherical aberration and the difference in Z or sign.
- FIGS. 3 (b) to 3 (e) show four types of aberration correcting optical elements 4 bi to 4 b 4 having different spherical aberration correction amounts and / or signs from each other.
- the height of the region 11 h is higher than the heights of the regions 11 g and 11 i by h, and the regions 11 f and 11 j Is lower by h than the heights of the regions 11 g and 11 i.
- the height of the area 1 lh is higher by 2 h than the heights of the areas 11 g and 11 i, and the areas 11 f and 1
- the height of 1 j is 2 h lower than the height of regions 11 g and 11 i.
- the region 1 1 height h is only h than the height of the region 1 1 g and 1 1 i lower region 1 1 f and 1 1
- the height of j is h higher than the height of regions 1 lg and 1 1 i.
- the height of the region 11 h is lower by 2 h than the heights of the regions 11 g and 11 i
- the height of 1 1 j is the area 1 1 g and 2 h higher than 1 1 i.
- the cross section in the Y direction passing through the center of the aberration correcting optical element 4b is the same as the cross section in the X direction passing through the center.
- the aberration correction optical element 4b having such a cross section can be manufactured by molding glass or plastic, or by depositing a dielectric on glass.
- the latter manufacturing method is low in manufacturing cost and excellent in mass productivity because a photolithography process can be applied.
- the aberration correcting optical element 4c shown in FIG. 4A is a plan view showing the aberration correction optical element 4c. As shown in FIG. 4 (a), the aberration correction optical element 4c is divided into five areas 11k to 11o. The broken line in the figure indicates the effective area of the objective lens 6.
- a circular area 11k whose center coincides with the center of the aberration correction optical element 4c is provided, and areas 11 1 to 11 o are provided outside the area 11 k.
- the region 11 1 is provided in the + Y direction
- the region 11 m is provided in the one Y direction
- the region 11 n is provided in the 1 X direction.
- the region 11 o is provided in the + X direction.
- the boundary line between the regions 11 1 to 11 o coincides with the diagonal line of the aberration correcting optical element 4c.
- the area 11 k is inside the effective area of the objective lens 6.
- FIG. 4 (b) (A) to (e) show four types of aberration correction optical elements 4 ci to 4 c 4 having different astigmatism correction amounts and Z or signs, and a cross-sectional view taken along line C-C ′ shown in FIG. 4 (a). it. as shown in FIG. 4 (b) to (e), X-direction cross-sectional shape passing through the center of the aberration correcting optical element 4 c ⁇ 4 c 4 is a two-level staircase.
- the height of the regions 11 n and 11 o is higher by h than the height of the region 11 k.
- the cross-sectional shape (not shown) in the Y direction passing through the center of the aberration correction optical element 4c is also a two-level stepped shape.
- the height of the regions 11 1 and 1 lm is lower by h than the height of the region 11 k.
- the height of the region 1 1 1 ⁇ Pi 1 lm is higher by h than the height of the region 1 1 k.
- FIG. 4 (e) yield difference shown in correcting optical element 4 c 4, the height of the region 1 1 1 ⁇ Pi 1 lm, only 2 h higher than the height of the region 1 1 k. That is, the surface shape of the aberration correcting optical element 4c is a three-level step as a whole.
- the aberration correcting optical element 4c having such a cross section can be manufactured by molding glass or plastic, or by depositing a dielectric on glass.
- the latter manufacturing method can be applied to the photolithography process, so the manufacturing cost is low and the mass productivity is excellent.
- FIG. 5A is a plan view showing the aberration correction optical element 4d.
- the entire shape of the aberration correcting optical element 4d is a regular hexagon when viewed from the optical axis direction.
- the aberration correction optical element 4 d has the region 11! ) ⁇ 11 V divided into seven regions. Note that the broken line in the figure indicates the effective area of the objective lens 6.
- a circular area 11 P whose center coincides with the center of the aberration correcting optical element 4d is provided, and the areas 11 q to 11 1 are provided outside this area 11 p.
- V is provided so as to be six-fold symmetric with respect to the center of the aberration correction optical element 4d.
- a region llq is provided in the one X direction
- a region 1 lr is provided in a direction inclined 60 ° from the + X direction to the one Y direction
- a + Y direction is provided from the + X direction.
- the area 11 s is provided in the direction tilted 60 ° to the right, the area 11 t is provided in the + X direction, and the area is provided in the direction tilted 60 ° from the X direction to the + Y direction.
- 11 u are provided, and a region 11 V is provided in a direction inclined 60 ° from the 1X direction to the 1Y direction. That is, the region 11 s, the region 11 t, the region 11 r, the region 11 v, the region 11 q, and the region 11 u are arranged in this order so as to surround the circular region 11 p. .
- the boundary line between 1 V and 11 V coincides with the diagonal line of the aberration correcting optical element 4d.
- the region 11 p is inside the effective region of the objective lens 6.
- the aberration correcting optical element 4 d is Ri by the difference of the correction amount and or sign of the arrow aberration can further four classes for the aberration correction optical element 4 (! ⁇ D 4.
- FIG. 5 (b) to (e) FIG. 5B is a cross-sectional view taken along line DD ′ shown in FIG. 5A showing four types of aberration correction optical elements 4 d to 4 d 4 having different amounts of correction and different signs of arrow-shaped aberration.
- FIG 5 (b) through (e) the cross-sectional shape of the X-direction passing through the center of the aberration correcting optical element 4 (! e ⁇ 4 d 4 is a three-level stepped.
- the height of the region 11 q is lower than the height of the region 11 p by h, and the height of the region 11 t is lower than that of the region 11 p. H higher than the height.
- the height of the region 11 q is lower than the height of the region 11 p by 2 h, and the height of the region 11 t is 2 h higher than 1 p.
- the height of the region 11 q is higher than the height of the region 11 p by h, and the height of the region 11 t is higher than the height of the region 1 lp. H only lower.
- the height of the region 11 q is higher than the height of the region 11 p by 2 h, and the height of the region 11 t is 2 h lower than 1 p.
- the shape of the element (not shown) in the section parallel to the direction inclined 60 ° from the + X direction to the one Y direction passing through the center of the aberration correction optical element 4 d is the same as the section parallel to the X direction. It has three levels of steps.
- the height of the region 11 r is lower than the height of the region 11 p by h
- the height of the region 1 lu is 11 1 It is higher by h than the height of p.
- the height in the area 11 is lower by 2 h than the height in the area 11 p, and the height in the area 11 u is 2 h higher than 1 p.
- the height of the region 11 r is higher than the height of the region 1 lp by h, and the height of the region 11 u is higher than the region 11 p. H lower than the height of
- the height of the region 1 lr is higher by 2 h than the height of the region 11 p
- the height of the region 11 u is higher than the region 11 1 2 h lower than the height of p.
- the shape of the element (not shown) in a section parallel to the direction inclined 60 ° from the + X direction to the + Y direction passing through the center of the aberration correcting optical element 4 d has the same shape as the section parallel to the X direction. It has three levels of steps.
- the height of the region 11 s is lower than the height of the region 11 p by h and the height of the region 11 V is It is h higher than 1 p.
- the height of the region 11 s is lower by 2 h than the height of the region 11 p, and the height of the region 11 V is 2 h higher than 1 p.
- the height of the region 1 1 s is higher by h than the height of the region 1 1 p, the height of the region 1 1 V is lower by h than the height of the region 1 1 p.
- the height of the region 11 s is higher by 2 h than the height of the region 11 P, and the height of the region 11 V is 2 h lower than 1 p.
- the aberration correction optical element 4d having such a cross section can be manufactured by molding glass or plastic, or by depositing a dielectric on glass.
- the latter manufacturing method has a low manufacturing cost and is excellent in mass productivity because a photolithography process can be applied.
- a semiconductor laser 1, a collimator lens 2, a polarizing beam splitter 3, a quarter-wave plate 5, and an objective lens 6 are arranged along the path of the laser light emitted from the semiconductor laser 1. Arrange them in order and assemble the optical system. Further, along the path of the light reflected by the polarization beam splitter 3, the cylindrical lens 8, the lens 9, and the photodetector 10 are arranged in this order.
- the aberration compensation optical element prepare the aberration ToTadashi optical element 4 a ⁇ 4 a 4, 4 bi ⁇ 4 b 4, 4 c 1 ⁇ 4 c 4, 4 di ⁇ 4 d 4 above.
- an aberration correcting optical element capable of correcting this aberration is provided as an aberration correcting optical element 4a! ⁇ 4 a 4, 4 b 1 ⁇ 4 b 4, 4 c 1 ⁇ 4 c 4, 4 di ⁇ 4 d 4 forces, et one or a plurality selected, the polarization beam splitter 3 the aberration correcting optical element 4 selected And the quarter-wave plate 5 so as to be interposed in the optical path.
- the aberration correction optical element 4 is rotated around the optical axis of the incident light so that the direction of the aberration corrected by the aberration correction optical element 4 matches the direction of the measured aberration. Meanwhile, the direction of the aberration correction optical element 4 may be adjusted. Thereby, the optical head device 21 is manufactured.
- the recording operation on the disk 7 will be described.
- recording data is externally input to the recording signal generation circuit 12.
- the recording signal generation circuit 12 generates a recording signal for driving the semiconductor laser 1 based on the input recording data, and outputs the recording signal to the semiconductor laser driving circuit 13.
- the semiconductor laser drive circuit 13 generates a drive signal based on the recording signal and outputs the drive signal to the semiconductor laser 1 of the optical head device 21.
- the semiconductor laser 1 emits a laser beam based on the input drive signal.
- This laser light is collimated by the collimator lens 2, enters the polarization beam splitter 3 as P-polarized light, is transmitted almost completely, and is transmitted through the aberration correcting optical element 4, whereby the aberration in the outward path is corrected. .
- this light is transmitted through the quarter-wave plate 5, converted from linearly polarized light into circularly polarized light, and focused on the disk 7 by the objective lens 6. As a result, data is written to the disk 7 and a signal is recorded.
- this light is reflected by the disk 7, passes through the objective lens 6 in the opposite direction, passes through the quarter-wave plate 5, and is converted from circularly polarized light into linearly polarized light whose polarization direction is orthogonal to the outward path.
- the element 4 Aberration in the return path is corrected, incident on the polarizing beam splitter 3 as S-polarized light, almost completely reflected, and emitted toward the cylindrical lens 8.
- This light is given astigmatism by passing through the cylindrical lens 8 and the lens 9 and is incident on the photodetector 10.
- a current signal is generated based on the intensity of the light received by each light receiving unit of the photodetector 10 and output to the preamplifier 14.
- the current signal input to the preamplifier 14 is The signal is converted to a signal and output to the reproduction signal generation circuit 15 and the error signal generation circuit 16. Then, the error signal generation circuit 16 generates a focus error signal and a track error signal for driving the objective lens 6 based on the voltage signal input from the preamplifier 14.
- the objective lens drive circuit 17 drives the actuator based on the focus error signal and the track error signal input from the error signal generation circuit 16 to control the position of the objective lens 6. Thereby, the operation of the focus servo and the track servo is performed.
- the semiconductor laser drive circuit 13 does not drive the semiconductor laser 1 based on recording data input from the outside, but causes the semiconductor laser 1 to emit laser light with a constant output. Then, by the same operation as the above-described recording operation, the laser light is condensed and reflected on the disk 7, and is taken out as a current signal by the photodetector 10.
- the preamplifier 14 converts the current signal into a voltage signal and outputs the voltage signal to the reproduction signal generation circuit 15 and the error signal generation circuit 16.
- the reproduction signal generation circuit 15 generates a reproduction signal based on the voltage signal input from the preamplifier 14 and outputs the reproduction signal to the outside as reproduction data. As a result, the signal from the disk 7 is reproduced.
- the operations of the error signal generation circuit 16, the objective lens drive circuit 17, and the actuator are the same as those at the time of data recording described above.
- FIG. 6 (a) to 6 (h) show the optical system or the aberration correcting optical element by taking the position in the cross section in the X direction passing through the center of the aberration correcting optical element 4a on the horizontal axis and the amount of aberration on the vertical axis.
- Fig. 4 is a graph showing the wavefront aberration of Fig. 4a, and the solid lines shown in Figs. 6 (a) to (d) occur in the optical system.
- the coma aberration is shown, the broken line shows the wavefront difference caused by the aberration correcting optical element 4a, and the solid lines shown in FIGS. 6 (e) to 6 (h) show the optical system using the aberration correcting optical element 4a.
- 2 shows the wavefront aberration when the coma aberration generated in is corrected.
- the coma generated in the optical system changes from positive side of the X axis to positive, negative, positive and negative from the positive side to RMS (root mean square: root mean square). (Square root)
- the wavefront aberration is 0.02 ⁇ .
- an aberration correcting optical element 4a shown in FIG. 2 (b) is used.
- the coma generated by the aberration-correcting optical element 4a changes from the negative side of the X-axis to the positive side, in the order of negative, positive, negative, and positive.
- the height h in Fig. 2 (b) is designed so that the residual RMS wavefront aberration is minimized when the coma shown in Fig.
- Fig. 6 (e) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the dashed line in Fig. 6 (a). It can be seen that the absolute value of the residual wavefront aberration approaches 0 ⁇ .
- Fig. 6 (b) the coma aberration generated in the optical system changes from the negative side of the X axis to positive, negative, positive, and negative, and the RMS wavefront aberration is 0.04 ⁇ . It is.
- the aberration correcting optical optical element 4 a 2 shown in Figure 2 (c) Coma aberration caused by the aberration correcting optical element 4 a 2 are negative towards the negative side of the X-axis to the positive side, positive, and changing negative, positive.
- Height 2 h in FIG. 2 (c) when the corrected indicates to coma in FIG 6 (b) using the aberration correcting optical element 4 a 2, as residual RM S wavefront aberration is minimum It is designed.
- Fig. 6 (f) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the dashed line in Fig. 6 (b). It can be seen that the absolute value of the residual wavefront aberration approaches 0 ⁇ .
- Fig. 6 (c) the coma generated in the optical system changes from negative to positive on the X-axis to negative, positive, negative, and positive, and the RMS wavefront aberration is 0.0. 2 ⁇ .
- the aberration correcting optical optical element 4 a 3 shown in Figure 2 (d).
- Coma aberration caused by the aberration correcting optical element 4 a 3 are positive toward the negative side of the X-axis to the positive side, negative, positive, and changing the negative.
- the height h in FIG. 2 (d) when correcting coma aberration shown in FIG. 6 (c) using the aberration correcting optical element 4 a 3, is designed to remain RMS wavefront aberration is minimized I have.
- Fig. 6 (g) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the broken line in Fig. 6 (c), and it can be seen that the absolute value of the residual wavefront aberration approaches 0 ⁇ .
- Fig. 6 (d) the coma generated in the optical system changes from negative to positive on the X-axis to negative, positive, negative, and positive, and the RMS wavefront aberration is 0.04 ⁇ . It is.
- To correct this coma aberration using the aberration capturing Masamitsu optical element 4 a 4 shown in FIG. 6 (e). Coma aberration caused by the aberration correcting optical element 4 a 4 a positive direction from the negative side of the X-axis to the positive side, negative, positive, and changing the negative.
- Height 2 h in FIG. 2 (e) when corrected indicates to coma in FIG 6 (d "using the aberration correcting optical element 4 a 4, set as residual RMS wavefront aberration is minimized
- Fig. 6 (h) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the dashed line in Fig. 6 (d), and the absolute value of the residual wavefront aberration approaches 0 ⁇ . Understand.
- the wavefront difference in the section in the ⁇ direction passing through the center of the aberration correction optical element 4a is ⁇ .
- the coma generated in the optical system has a maximum RMS wavefront aberration of 0.05 ⁇ .
- four types of aberration correcting optical elements 4a shown in FIGS. 2B to 2E are prepared.
- the amount and sign of the coma generated in the optical system other than the aberration correcting optical element 4a are measured by an interferometer or the like.
- four types of aberration correcting optical elements 4 ai to 4 a 4 From among the above, one kind of aberration correction optical element 4a is selected as necessary so as to minimize the residual RMS wavefront aberration after correction, and is introduced into the optical system.
- the coma aberration correction using the aberration correction optical element 4a is not performed.
- the aberration correction optical element 4a shown in Fig. 2 (b) or the aberration shown in Fig. 2 (d) depends on the sign of coma. to correct the coma aberration by using the correction optical element 4 a 3.
- the residual RMS wavefront aberration after correction can be reduced to about 0.01 ⁇ or less. If RMS wavefront aberration is less large 0. 05 lambda than 0.
- the residual RMS wavefront aberration after the correction can be reduced to about 0.01 ⁇ or less.
- four types of the aberration correction optical element 4a are used.However, as the number of types of the aberration correction optical element 4a having different coma aberration correction amounts and / or signs increases, The residual RMS wavefront aberration can be reduced.
- the case where the direction of the coma aberration generated in the optical system is the X direction has been described in FIGS. 2 and 6, the case where the direction of the coma aberration generated in the optical system is different from the X direction is also described. If the aberration correction optical element 4a is installed by rotating it in a plane perpendicular to the optical axis of the incident light so that the direction and the direction of the coma that can be corrected by the aberration correction optical element 4a substantially match, Can be corrected.
- FIG. 7A to 7H the horizontal axis indicates the position in the cross section in the X direction passing through the center of the aberration correction optical element 4b, and the vertical axis indicates the amount of aberration.
- 7B is a graph showing the wavefront aberration of FIG. 7B.
- the solid lines shown in FIGS. 7A to 7D show the spherical aberration generated in the optical system, and the broken lines show the wavefront aberration generated by the aberration correction optical element 4b.
- Figure 7 (e) to (h) The solid line shown in Fig. 7 shows the wavefront aberration when spherical aberration generated in the optical system is corrected using the aberration correction optical element 4b.
- the spherical aberration generated in the optical system changes from the negative side of the X axis to positive, negative, positive, negative, positive, and the RMS wavefront aberration is 0. 0 2.
- an aberration correction optical element 4bi shown in FIG. 3 (b) is used.
- the spherical aberration generated by the aberration correction optical element 4 b i is
- FIG. 7 (e) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the broken line in FIG. 7 (a), and it can be seen that the absolute value of the residual wavefront aberration approaches 0 ⁇ .
- the spherical aberration that occurs in the optical system changes from the negative side of the X axis to positive, negative, positive, negative, positive, and the RMS wavefront aberration is 0. 0 4.
- the aberration correcting optical element 4 b 2 shown in Figure 3 (c) The spherical aberration generated by the aberration correction optical element 4 b 2 is
- Negative, positive, negative, positive, negative changes from the negative side of the X axis to the positive side.
- Height 2 h in FIG. 3 (c) designed when correcting the spherical aberration shown in FIG. 7 (b) using the aberration correcting optical element 4 b 2, to so that a residual RMS wavefront aberration is minimum Have been.
- Fig. 7 (f) shows the residual wavefront aberration at this time.
- the spherical aberration generated in the optical system changes from negative to positive on the X-axis to negative, positive, negative, positive, and negative, and the RMS wavefront aberration is 0. 0 2 ⁇ .
- the spherical aberration generated by the aberration correction optical element 4 b 3 is From the negative side of the X-axis to the positive side, it changes as positive, negative, positive, negative, positive.
- the height h in FIG. 3 (d) when correcting the spherical aberration shown in FIG.
- Fig. 7 (g) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the broken line in Fig. 7 (c), and it can be seen that the absolute value of the residual wavefront aberration approaches 0 ⁇ .
- the spherical aberration produced by the optical system changes from negative to positive on the X-axis, going negative, positive, negative, positive, negative, and the RMS wavefront aberration is 0.04.
- ⁇ To correct the spherical aberration, using the aberration ToTadashi optical element 4 b 4 shown in FIG. 3 (e).
- Spherical aberration caused by the aberration ToTadashi optical element 4 b 4 are positive toward the negative side of the X-axis to the positive side, negative, positive, and changing negative, positive.
- Fig. 7 (h) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the dashed line in Fig. 7 (d). It can be seen that the absolute value of the residual wavefront aberration approaches 0 ⁇ .
- the wavefront difference in the section in the ⁇ direction passing through the center of the aberration correcting optical element 4b is the same as the wavefront aberration in the section in the X direction passing through the center.
- the spherical aberration generated in the optical system is at most 0.05 as the RMS wavefront aberration.
- four types of aberration correction optical elements 4b shown in FIGS. 3 (b) to 3 (e) are prepared. Then, the amount and sign of the spherical aberration generated in the optical system from the semiconductor laser 1 to the objective lens 6, excluding the aberration correcting optical element 4b, are measured by an interferometer or the like. Next, according to the measured amount and sign of the spherical aberration, one of the four types of aberration correction optical element 4b is used, if necessary, so that the residual RMS wavefront aberration after correction is minimized. Select the correction optical element 4b and insert it into the optical system.
- the RMS wavefront aberration is 0.01 0 or less. If it is below, the spherical aberration is not corrected by the aberration correcting optical element 4b.
- the aberration correction optical element 4b shown in Fig. 3 (b) or the aberration correction optical element shown in Fig. 3 (d) is used according to the sign of the spherical aberration
- the spherical aberration is corrected using the aberration correction optical element 4b3.
- the residual RMS wavefront aberration after the correction can be reduced to about 0.01 or less. If RMS wavefront aberration is less large 0. 05 lambda than 0.
- aberration shown in the aberration correcting optical element 4 b 2 or FIG. 3 (e) shown in FIG. 3 (c) performs compensation of the spherical aberration by using the correction optical element 4 b 4.
- four types of the aberration correction optical element 4 b are used. However, as the number of types of the aberration correction optical element 4 b having different spherical aberration correction amounts and / or signs increases, the residual RMS wavefront after correction increases. Aberration can be reduced.
- FIG. 8 is a graph showing the wavefront aberration of c, wherein the solid lines shown in FIGS. 8A to 8D show astigmatism generated in the optical system, and the broken lines show the wavefront aberration generated by the aberration correction optical element 4c.
- 8 (e) to 8 (h) show the wavefront aberration when astigmatism generated in the optical system is corrected by using the aberration correction optical element 4c.
- FIG. 8 (a) the astigmatism generated in the optical system changes from negative to positive on the X-axis to negative, 0, and negative, and the RMS wavefront aberration is 0.02 ⁇ . It is.
- an aberration correcting optical element 4 c shown in FIG. 4B is used.
- the astigmatism generated in the aberration correction optical element 4 c changes from positive to negative on the X-axis to positive, zero, and positive.
- the height h in Fig. 4 (b) is calculated by using the aberration correction optical element 4 ci as shown in Fig. 8 (a). It is designed to minimize residual RMS wavefront aberrations when correcting aberrations.
- Figure 8 (e) residual wavefront aberration at this time, i.e., FIG. 8 (a) shows the sum of the solid and dashed, residual wavefront absolute value I that force S is approaching 0 lambda force aberration 2> You.
- FIG. 8 (b) shows the astigmatism generated in the optical system changes from the negative side of the X-axis to negative, 0, and negative from the positive side, and the RMS wavefront aberration is 0.04 ⁇ . .
- the astigmatism is corrected, using the aberration correcting optical element 4 c 2 shown in FIG. 4 (c).
- Astigmatic aberration caused by the aberration correcting optical element 4 c 2 is positive toward the negative side of the X-axis to the positive side, 0, and positive and change.
- Contact Keru height 2 h in FIG. 4 (c) when corrected for astigmatism shown in Fig. 8 (b) by using the aberration ToTadashi optical element 4 c 2, residual RMS wavefront aberration is minimized It is designed to be.
- FIG. 8 (f) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the broken line in FIG. 8 (b), and it can be seen that the absolute value of the residual wavefront aberration is approaching 0 ⁇ .
- Fig. 8 (c) the astigmatism generated in the optical system changes from the negative side of the X axis to positive, 0, and positive from the negative side to the positive side, and the RMS wavefront aberration is 0.02 ⁇ . .
- the astigmatism is corrected, using the aberration correcting optical element 4 c 3 shown in FIG. 4 (d).
- Astigmatic aberration caused by the aberration correcting optical element 4 c 3 are negative towards the negative side of the X-axis to the positive side, 0, is changed to the negative.
- Contact Keru height h in FIG. 4 (d) when corrected for astigmatism shown in FIG. 8 (c) using the aberration correcting optical element 4 c 3, as residual RMS wavefront aberration is minimized It is designed.
- Fig. 8 (g) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the dashed line in Fig. 8 (c). It can be seen that the absolute value of the residual wavefront aberration approaches 0 ⁇ .
- the astigmatism generated in the optical system changes from the negative side of the X axis to positive, 0, and positive from the negative side to the positive side, and the RMS wavefront aberration is 0.04 ⁇ . It is.
- the astigmatism is corrected, using the aberration correcting optical element 4 c 4 shown in FIG. 4 (e).
- Astigmatic aberration caused by the aberration correcting optical element 4 c 4 are negative towards the negative side of the X-axis to the positive side, 0, is changed to the negative.
- Contact Keru 2 height h in FIG. 4 (e) when corrected for astigmatism shown in FIG.
- Fig. 8 (h) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the dashed line in Fig. 8 (d), and it can be seen that the absolute value of the residual wavefront aberration approaches 0 ⁇ .
- the sign of the wavefront aberration in the section in the ⁇ direction passing through the center of the aberration correcting optical element 4c is opposite to the sign of the wavefront aberration in the section in the X direction passing through the center.
- the astigmatism generated in the optical system is at most 0.05 ⁇ as the RMS wavefront aberration.
- four types of aberration correction optical elements 4c shown in FIGS. 4B to 4E are prepared.
- the amount and sign of astigmatism generated in the optical system from the semiconductor laser 1 to the objective lens 6 excluding the aberration correcting optical element 4c are measured by an interferometer or the like.
- one of the four types of aberration correcting optical elements 4 ci to 4 c 4 may be used as necessary to minimize the residual RMS wavefront aberration after correction. Select the aberration correction optical element 4c, and insert it into the optical system.
- the astigmatism correction using the aberration correction optical element 4c is not performed.
- the aberration correcting optical element 4 c or 4 d shown in FIG. 4B according to the sign of the astigmatism is used.
- the aberration ToTadashi optical element 4 c 3 shown in and to correct the astigmatism can be reduced to about 0.01 ⁇ or less.
- the aberration correcting optical element 4 c 2 or 4 e shown in FIG. 4C according to the sign of astigmatism is used. line correction of astigmatism by using the aberration correcting optical element 4 c 4 shown in U.
- the residual RMS wavefront aberration after the correction can be reduced to about 0.1 ⁇ ⁇ or less.
- the aberration correction optical element 4c is rotated and installed in a plane perpendicular to the optical axis of the incident light so that the direction and the direction of astigmatism that can be corrected by the aberration correction optical element 4c substantially match. For example, astigmatism can be corrected.
- FIG. 9 is a graph showing the wavefront aberration of d, the solid line shown in FIGS. 9 (a) to 9 (d) shows the arrow-shaped aberration generated in the optical system, and the broken line shows the wavefront aberration generated by the aberration correction optical element 4d.
- 9 (e) to 9 (h) show the wavefront aberration when the arrow-shaped aberration generated in the optical system is corrected using the aberration correction optical element 4d.
- Fig. 9 (a) the arrow-shaped aberration generated in the optical system changes from the negative side of the X axis to positive, 0, and negative from the negative side, and the RMS wavefront aberration is 0.02 ⁇ . .
- an aberration correcting optical element 4 shown in FIG. 5 (b) is used.
- the arrow-shaped aberration generated by the aberration correcting optical element 4 d changes from negative to positive on the X-axis to negative, 0, and positive.
- the height h in Fig. 5 (b) is designed so that the residual RMS wavefront aberration is minimized when the aberration correction optical element 4 is used to correct the arrow-shaped aberration shown in Fig. 9 (a).
- Fig. 9 (e) shows the residual wavefront aberration at this time, that is, the solid line in Fig. 9 (a). The sum of the dashed lines indicates that the absolute value of the residual wavefront aberration is approaching 0 ⁇ .
- Fig. 9 (b) the arrow-shaped aberration generated in the optical system changes from the negative side of the X axis to positive, 0, and negative from the negative side, and the RMS wavefront aberration is 0.04.
- the aberration correcting optical element 4 d 2 shown in FIG. 5 (c) Arrows aberration caused by the aberration ToTadashi optical element 4 d 2 is negative toward the negative side of the X-axis to the positive side, 0, and positive and change.
- Contact Keru height 2 h in FIG. 5 (c) when the corrected arrow aberration shown in FIG. 9 using the aberration ToTadashi optical element 4 d 2 (b), the residual RMS wavefront aberration is minimized It is designed to be.
- FIG. 9 (f) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the dashed line in Fig. 9 (b), and the fact that the absolute value of the residual wavefront aberration is approaching 0 ⁇ gives a force S .
- Fig. 9 (c) the arrow-shaped aberration generated in the optical system changes from the negative side of the X axis to negative, 0, and positive from the negative side to the positive side, and the RMS wavefront aberration is 0.02 ⁇ . .
- the aberration correcting optical element 4 d 3 shown in FIG. 5 (d) Arrows aberration caused by the aberration correcting optical element 4 d 3 is positive toward the negative side of the X-axis to the positive side, 0, is changed to the negative.
- Contact Keru height h in FIG. 5 (d) when corrected arrow aberration shown in FIG. 9 using the aberration correcting optical element 4 d 3 (c), so that the residual RM S wavefront aberration is minimum It is designed for.
- Fig. 9 (g) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the dashed line in Fig. 9 (c), and it can be seen that the absolute value of the residual wavefront aberration approaches 0 ⁇ .
- Fig. 9 (d) the arrow-shaped aberration generated in the optical system changes from negative to positive on the X-axis to negative, 0, and positive, and the RMS wavefront aberration is 0.04.
- the arrow-shaped aberration generated by the aberration correction optical element 4 d 4 is From the negative side to the positive side, it changes to positive, 0, negative.
- Figure 5 (e) to your Keru height 2 h upon correcting the arrows aberration shown in FIG. 9 using the aberration correcting optical element 4 d 4 (d), so that the residual RMS wavefront aberration is minimized It is designed for.
- Fig. 9 (h) shows the residual wavefront aberration at this time, that is, the sum of the solid line and the broken line in Fig. 9 (d), and it can be seen that the absolute value of the residual wavefront aberration is approaching zero.
- the wavefront aberration in the section passing through the center of the aberration correcting optical element 4 d and parallel to the direction inclined by 60 ° from the + X direction to the one Y direction is the wavefront aberration in the section parallel to the X direction passing through the center.
- the wavefront aberration in a cross section passing through the center of the aberration correction optical element 4 d and parallel to the direction inclined 60 ° from the + X direction to the + Y direction is the same as the wavefront aberration in the cross section passing through the center and parallel to the X direction. It is the same.
- the arrow-shaped aberration generated in the optical system has a maximum RMS wavefront aberration of 0.05 ⁇ .
- four types of aberration correcting optical elements 4d shown in FIGS. 5B to 5E are prepared.
- the amount and sign of the arrow-shaped aberration generated in the optical system from the semiconductor laser 1 to the objective lens 6, excluding the aberration correction optical element 4d are measured by an interferometer or the like.
- one of the four types of aberration correcting optical elements 4 di to 4 d 4 may be used as necessary so that the residual RMS wavefront aberration after correction is minimized.
- Select the type of aberration correction optical element 4 d and insert it into the optical system.
- the correction of the arrow-shaped aberration using the aberration correction optical element 4d is not performed.
- the aberration correction optical element 4d shown in Fig. 5 (b) or Fig. 5 (d) depends on the sign of the arrow-shaped difference.
- the arrow-shaped aberration is corrected using the aberration correction optical element 4 d 3 shown in FIG. As a result, the residual RMS wavefront aberration after correction can be reduced to about 0.01 or less.
- the RMS wavefront aberration is greater than 0.03 and less than 0.05 ⁇
- the residual RMS wavefront aberration after the correction can be reduced to about 0.1 ⁇ ⁇ or less.
- four types of the aberration correction optical element 4 d are used.However, as the number of types of the aberration correction optical element 4 d having different correction amounts and / or signs of the sagittal aberration increases, the residual after the correction increases.
- RMS wavefront aberration can be reduced.
- the direction of the arrow-shaped aberration generated in the optical system is tilted by 60 ° from the X direction, + X direction to one Y direction, and tilted by 60 ° from the + X direction to + Y direction.
- the direction of the arrow-shaped aberration generated in the optical system is tilted by 60 ° from the X direction, + X direction to one Y direction, and tilted by 60 ° from the + X direction to + Y direction.
- the aberration-correcting optical element 4 d is placed in a plane perpendicular to the optical axis of the If it is rotated and installed inside, it is possible to correct arrow-shaped aberration.
- a plurality of types of aberration correction optical elements 4 are prepared, and the aberration of the optical system except the aberration correction optical element 4 in the optical head device 21 is measured.
- the aberration of the optical system of the optical head device 21 can be easily determined by selecting one of the aberration correction optical elements 4 according to the type, sign, and correction amount of the optical head device 21 and incorporating it into the optical head device 21. Can be reduced.
- any one of the aberration correcting optical elements 4 a, 4 b, 4 c, and 4 d is used to obtain coma generated in the optical system and spherical aberration.
- the case of correcting any one of aberration, astigmatism, and arrow-shaped aberration has been described, but any two or more aberration correction optical elements are used to correct any two or more aberrations. It is also possible.
- the light path from the semiconductor laser 1 of the optical head device 21 to the objective lens 6 When the aberrations generated on the road include two kinds of aberrations among coma, spherical aberration, astigmatism, and arrow-shaped aberration, two aberration correcting optical elements for correcting each aberration may be incorporated.
- the optical path includes three types of aberrations, coma, spherical aberration, astigmatism, and arrow-shaped aberration, which are generated in the light path, three aberration correcting optical elements for correcting each aberration are provided. May be incorporated.
- the aberration generated in the light path includes all of coma, spherical aberration, astigmatism, and arrow-shaped aberration, four aberration correction optical elements for correcting each aberration may be incorporated. .
- the number of levels of the step-like pattern in the aberration correction optical elements 4a, 4b, 4c, and 4d shown in FIGS. 2 to 5 is three, but any number of levels may be used as long as it is two or more. . As the number of levels increases, the residual RMS wavefront aberration can be reduced.
- FIGS. 10A to 10E are diagrams showing the aberration correcting optical element 4e in the present embodiment
- FIGS. 11A to 11E show the aberration correcting optical element 4f in the present embodiment
- FIGS. 12A to 12E are diagrams showing the aberration correcting optical element 4 g according to the present embodiment
- FIGS. 13A to 13E are aberration correcting optical elements according to the present embodiment.
- FIG. 6 is a view showing an element 4h.
- (A) of each figure is a plan view
- (b) to (e) are sectional views.
- This embodiment is different from the first embodiment described above in that the aberration correction optical element 4 is selected from aberration correction optical elements 4 e to 4 h shown in FIGS. 10 to 13 as aberration correction optical elements 4. The difference is that an optical element is used.
- Other configurations and operations in the present embodiment are the same as those in the first embodiment described above.
- FIG. 10 shows the aberration
- FIG. 9 is a plan view showing a correction optical element 4e.
- the aberration correction optical element 4e is composed of a single region, eliminates the steps on the surface of the aberration correction optical element 4a shown in FIGS. 2 (a) to 2 (e), and replaces the entire surface with a single curved surface. It was formed with.
- the circle drawn by the two-dot chain line in the figure corresponds to the effective area of the objective lens 6.
- FIGS. 10 (b) to 10 (e) are cross-sectional views taken along the line E-E 'shown in FIG. 10 (a) showing four types of aberration correcting optical elements 4e having different coma aberration correction amounts and different Zs or signs. is there.
- the contour of the element in a section passing through the center and parallel to the X direction is curved.
- the aberration correction optical element 4e having such a cross section can be manufactured by molding glass or plastic.
- the height increases from the center toward the negative side of the X axis, then decreases, and then decreases from the center toward the positive side of the X axis. The height once decreases and then increases. The height of the highest point is H higher than the height of the center, and the height of the lowest point is H lower than the height of the center.
- the height increases from the center toward the negative side of the X axis, then decreases, and then decreases from the center toward the positive side of the X axis. The height is low and then high.
- the height of the highest point is 2H higher than the height of the center, and the height of the lowest point is 2H lower than the height of the center.
- the height temporarily decreases from the center to the negative side of the X axis, then increases, and then moves from the center to the positive side of the X axis. The height becomes higher and then lower.
- the height of the highest point is H higher than the height of the center, and the height of the lowest point is H lower than the height of the center.
- the height of the highest point is 2H higher than the height of the center, and the height of the lowest point is the height of the center. 2H lower than that.
- the cross section in the Y direction passing through the center of the aberration correction optical element 4e is flat.
- the wavefront difference in the cross section in the X direction passing through the center of the aberration correction optical element 4e when the coma aberration generated in the optical system is corrected using the aberration correction optical element 4e is the same as that shown in FIG.
- the aberration correction optical element 4ei shown in FIG. 10 (b) is used.
- the height H in Fig. 10 (b) is set so that the coma shown in Fig. 6 (a) can be completely corrected using the aberration correction optical element 4e, that is, the residual RMS wavefront aberration is reduced to 0 ⁇ . It is designed to be When correcting the coma aberration shown in FIG.
- the wavefront difference in the section in the Y direction passing through the center of the aberration correction optical element 4e is 0 ⁇ .
- the coma generated in the optical system has a maximum RMS wavefront aberration of 0.05 ⁇ .
- four types of aberration correcting optical elements 4e shown in FIGS. 10B to 10E are prepared. And, except for the aberration correction optical element 4e, the semiconductor The amount and sign of coma generated in the optical system from the laser 1 to the objective lens 6 are measured by an interferometer or the like. After that, according to the amount and sign of the measured coma aberration, one of the four types of aberration correction optical element 4 e is provided with one type of aberration as necessary so that the residual RMS wavefront aberration after correction becomes the smallest. Select the correction optical element 4e and insert it into the optical system.
- the coma aberration correction using the aberration correction optical element 4 e is not performed. If the RMS wavefront aberration is greater than 0.01 ⁇ and less than 0.03, the aberration correction optical element 4ei shown in Fig. 10 (b) or the aberration correction shown in Fig. 10 (d) is used according to the sign of the comma aberration. It intends line correction of coma aberration using the optical element 4 e 3. As a result, the residual RMS wavefront aberration after the correction can be reduced to 0.01 or less.
- the aberration correction optical element 4 e 2 or 10 e shown in FIG. performing coma correction using the aberration ToTadashi optical element 4 e 4 shown.
- the residual RMS wavefront aberration after correction can be reduced to 0.01 ⁇ or less.
- FIG. 10 illustrates the case where the direction of the coma aberration generated in the optical system is the X direction
- the direction and the aberration correction optical The coma aberration is corrected by rotating the aberration correction optical element 4e in a plane perpendicular to the optical axis of the incident light so that the directions of the coma difference that can be corrected by the element 4e are approximately the same. be able to.
- the aberration correction optical element 4 f shown in FIG. 11 can be used as the aberration correction optical element 4.
- FIG. 11A is a plan view of the aberration correction optical element 4f.
- the aberration correction optical element 4 f is a single In this case, there is no step on the surface of the aberration correction optical element 4b shown in FIGS. 3 (a) to 3 (e), and the whole is formed by a single curved surface.
- the circle drawn by the two-dot chain line in the figure corresponds to the effective area of the objective lens 6.
- FIGS. 11 (b) to 11 (e) are cross-sectional views taken along line FF ′ shown in FIG. 11 (a) showing four types of aberration correction optical elements 4f having different amounts of correction of spherical aberration and / or different signs. It is.
- the contour of the element in a section passing through the center and parallel to the X direction is curved.
- the aberration correction optical element 4 f having such a cross section can be manufactured by molding glass or plastic.
- the height once increases from the center toward the positive and negative sides of the X axis, and then decreases.
- the height of the highest point is 2H higher than the height of the lowest point.
- the aberration correcting optical element 4 f 2 shown in FIG. 1 1 (c) lower then has decreased rather high gar ⁇ toward the positive ⁇ Pi negative side of the X-axis from the center.
- the height of the highest point is 4H higher than the height of the lowest point.
- the height in towards heart to the positive and negative side of the X axis increases after became over ⁇ low.
- the height of the highest point is 2H higher than the height of the lowest point.
- the aberration correcting optical element 4 f 4 shown in FIG. 1 1 (e) higher after connexion height suited from the center to the positive and negative side of the X axis becomes temporarily lower.
- the height of the highest point is 4H higher than the height of the lowest point.
- the cross section in the Y direction passing through the center of the aberration correction optical element 4 f is the same as the cross section in the X direction passing through the center.
- the wavefront difference in the cross section in the X direction passing through the center of the aberration correction optical element 4f when correcting the spherical aberration generated in the optical system using the aberration correction optical element 4f is the same as that shown in FIG. That is, when the spherical aberration shown in FIG. 7A is corrected, the aberration correction optical element 4 f shown in FIG. 11B is used.
- the height H in Fig. 11 (b) is calculated by using the aberration correction optical element 4f in Fig. 7 (a). It is designed to completely correct the spherical aberration shown in (1), that is, the residual RMS wavefront aberration becomes zero.
- the wavefront difference in the section in the ⁇ direction passing through the center of the aberration correcting optical element 4 f is the same as the wavefront aberration in the section in the X direction passing through the center.
- the spherical aberration generated in the optical system is at most 0.05 ⁇ as the RMS wavefront aberration.
- four types of aberration correction optical elements 4f shown in FIGS. 11 (b) to (e) are prepared.
- the amount and sign of the spherical aberration generated in the optical system from the semiconductor laser 1 to the objective lens 6 excluding the aberration correction optical element 4 f are measured by an interferometer or the like.
- one of the four types of aberration correction optics 4 f if necessary, so that the residual RMS wavefront aberration after correction is minimized. Select the optical element 4 f and insert it into the optical system.
- the spherical aberration is not corrected using the aberration correcting optical element 4 f. If the RMS wavefront aberration is greater than 0.01 ⁇ and less than 0.03 ⁇ , the sign of spherical aberration Depending on the signal, spherical aberration is corrected using the aberration correcting optical element 4 f shown in FIG. 11B or the aberration correcting optical element 4 f 3 shown in FIG. 11D. As a result, the residual RMS wavefront aberration after correction can be reduced to 0.01 ⁇ or less.
- the aberration correcting optical element 4 f 2 shown in Fig. 11 (c) or Fig. 11 (e) according to the sign of the spherical aberration The spherical aberration is corrected using the aberration correcting optical element 4 f 4 shown in FIG.
- the residual RMS wavefront aberration after the correction can be reduced to 0.01 ⁇ or less.
- four types of aberration correction optical element 4 f were used. ⁇ The more the amount of spherical aberration correction and the type of aberration correction optical element 4 f with different Z or sign, the smaller the residual RMS wavefront aberration after correction. can do.
- FIG. 12A is a plan view of the aberration correction optical element 4 g.
- the aberration correction optical element 4g is composed of a single area, eliminates the steps on the surface of the aberration correction optical element 4c shown in FIGS. 4 (a) to 4 (e), and has a single curved surface as a whole. It was formed.
- the circle drawn by the two-dot chain line in the figure corresponds to the effective area of the objective lens 6.
- FIGS. 12 (b) to 12 (e) are cross-sectional views along line GG ′ shown in FIG.
- the aberration correcting optical element 4 g having such a cross section can be manufactured by molding glass or plastic.
- the height increases from the center toward the positive and negative sides of the X-axis.
- the height of the highest point is H higher than the height of the center.
- the height increases from the center toward the positive and negative sides of the X axis. Highest point high The height is 2H higher than the height of the center.
- the height decreases from the center toward the positive and negative sides of the X axis. The height of the lowest point is lower by H than the height of the center.
- the height decreases from the center toward the positive and negative sides of the X axis.
- the height of the lowest point is 2H lower than the height of the center.
- the profile of the element in a cross section parallel to the Y direction passing through the center of the aberration correction optical element 4 g is curved like the cross section parallel to the X direction.
- the height decreases from the center toward the positive and negative sides of the Y axis.
- the height of the lowest point is H lower than the height of the center.
- the height decreases from the center toward the positive and negative sides of the Y axis.
- the height of the lowest point is 2H lower than the height of the center.
- the height increases from the center toward the positive and negative sides of the Y axis.
- the height of the highest point is H higher than the height of the center.
- the height increases from the center toward the positive and negative sides of the Y-axis.
- the height of the highest point is 2H higher than the height of the center.
- the wavefront difference in the cross section in the X direction passing through the center of the aberration correcting optical element 4 g is the same as that shown in FIG. . That is, when correcting the astigmatism shown in FIG. 8A, the aberration correcting optical element 4 gl shown in FIG. 12B is used.
- the height H in Fig. 12 (b) is set so that the astigmatism shown in Fig. 8 (a) can be completely corrected using the aberration correcting optical element 4g, that is, the residual RMS wavefront aberration is reduced to zero. Designed to be.
- FIG. 8 (b) using the aberration correcting optical element 4 g 2 shown in FIG. 1 2 (c).
- Height 2 H in FIG. 1 2 (c) is shown in FIG. 8 (b) using the aberration ToTadashi optical element 4 g 2 It is designed so that astigmatism can be completely corrected, that is, the residual RMS wavefront aberration becomes 0 ⁇ .
- the aberration correcting optical element 4 g 3 shown in FIG. 12 (d) is used.
- Contact Keru height H in FIG. 1 2 (d) as can be completely corrected non TenOsamu difference shown in FIG.
- the aberration correcting optical element 4 g 4 shown in FIG. 12E is used. Height 2H in FIG 1 2 (e), as the astigmatism shown in FIG. 8 (d) using the aberration correcting optical element 4 g 4 fully ToTadashi, i.e., residual RMS wavefront aberration is 0 lambda It is designed to be
- the sign of the wavefront aberration in the section in the ⁇ direction passing through the center of the aberration correcting optical element 4 g is opposite to the sign of the wavefront aberration in the section in the X direction passing through the center.
- one type of aberration correcting optical element 4 g is selected as necessary so that the residual RMS wavefront aberration after capture is minimized, and is included in the optical system. Buy. Specifically, when the RMS wavefront aberration is less than 0.01 ⁇ , the astigmatism correction using the aberration correction optical element 4g is not performed. When the RMS wavefront aberration is larger than 0.01 ⁇ and smaller than 0.03 ⁇ , the aberration correcting optical element 4 g shown in FIG. 12B or FIG. d) Astigmatism is corrected using the aberration correction optical element 4 g 3 shown in (d). This makes it possible to reduce the residual RMS wavefront aberration after correction to 0.01 ⁇ or less.
- the astigmatism using the aberration correcting optical element 4 g 2 shown in FIG. 12 (c) or the aberration correcting optical element 4 g 4 shown in FIG. make corrections.
- the residual RMS wavefront aberration after correction can be reduced to 0.01 ⁇ or less.
- the type of the aberration correcting optical element 4 g is set to four types.However, as the astigmatism correction amount and the type of the aberration correcting optical element 4 g having a different Z or sign increase, the residual RMS wavefront aberration after correction increases. Can be reduced.
- FIG. 12 describes the case where the direction of astigmatism generated in the optical system is the XY direction
- the case where the direction of astigmatism generated in the optical system is different from the XY direction is also described.
- the aberration-correcting optical element 4 g is rotated and installed in a plane perpendicular to the optical axis of the incident light so that the direction and the direction of astigmatism that can be corrected by the aberration-correcting optical element 4 g substantially match. Astigmatism can be corrected.
- FIG. 13A is a plan view of the aberration correction optical element 4h.
- the aberration correction optical element 4 h is composed of a single area, and eliminates the steps on the surface of the aberration correction optical element 4 d shown in FIGS. 5 (a) to 5 (e) to form a single curved surface as a whole. It was formed by The circle drawn by the two-dot chain line in the figure corresponds to the effective area of the objective lens 6.
- FIGS. 13 (b) to 13 (e) are cross-sectional views taken along the line H—H ′ shown in FIG. FIG. As shown in FIGS. 13 (b) to 13 (e), the contour of the element in a section passing through the center and parallel to the X direction is curved.
- the aberration correction optical element 4h having such a cross section can be manufactured by molding glass or plastic.
- the X-axis from the center The height decreases toward the negative side of, and increases from the center toward the positive side of the X axis.
- the height of the highest point is H higher than the height of the center, and the height of the lowest point is H lower than the height of the center.
- the height of the highest point is 2 H higher than the height of the center, and the height of the lowest point is 2 H lower than the height of the center.
- the height increases toward the negative side of the X-axis from the center, low X-axis positive suited One in height to the side from the center Become.
- the height of the highest point is H higher than the height of the center, and the height of the lowest point is H lower than the height of the center.
- the height increases toward the negative side of the X-axis from the center, the height becomes lower toward the center to the positive side of the X-axis .
- the height of the highest point is 2 H higher than the height of the center, and the height of the lowest point is 2 H lower than the height of the center.
- the contour of the element passing through the center of the aberration correcting optical element 4 h and parallel to the direction inclined 60 ° from the + X direction to the one Y direction is curved like the cross section parallel to the X direction.
- the height decreases from the center in the direction inclined 60 ° from the + X direction to the one Y direction, and the height decreases from the center to the + X direction.
- the height increases in the direction inclined 60 ° in the Y direction.
- the height of the highest point is H higher than the height of the center, and the height of the lowest point is H lower than the height of the center.
- the height becomes lower toward the direction tilted 60 ° to single Y-direction from the + X direction from the center, from the -X direction + Height increases in the direction inclined 60 ° in the Y direction.
- the height of the highest point is 2 H higher than the height of the center, and the height of the lowest point is 2 H lower than the height of the center.
- the aberration correcting optical element 4 h 3 shown in FIG. 13 (d) from the center, The height increases in the direction inclined 60 ° from the + X direction to the Y direction, and decreases from the center in the direction inclined 60 ° from the X direction to the + + direction.
- the height of the highest point is ⁇ higher than the height of the center, and the height of the lowest point is ⁇ lower than the height of the center.
- the aberration correcting optical element 4 h 4 shown in Fig. 1 3 (e) from the center, + 60 ° tilted toward selfish height direction from the X direction to the one Y-direction is increased from the center, from a X direction + The height decreases toward the direction inclined 60 ° in the Y direction.
- the height of the highest point is 2 H higher than the height of the center, and the height of the lowest point is 2 H lower than the height of the center.
- the profile of the element passing through the center of the aberration correcting optical element 4h and parallel to the direction inclined by 60 ° from the + X direction to the + Y direction has the same curved shape as the cross section parallel to the X direction.
- the height decreases from the center in the direction inclined 60 ° from the + X direction to the + Y direction, and from the center, from one X direction.
- the height increases in the direction inclined 60 ° in the Y direction.
- the height of the highest point is H higher than the height of the center, and the height of the lowest point is H lower than the height of the center.
- the height of the highest point is H higher than the height of the center, and the height of the lowest point is H lower than the height of the center.
- the aberration correcting optical element 4 h 4 shown in Fig. 1 3 (e) from the center, the higher the direction selfish height from the + X direction + Y direction to the 60 ° inclined direction, from the center, from a X direction Tilted 60 ° in Y direction The height decreases toward the direction.
- the height of the highest point is 2 H higher than the height of the center, and the height of the lowest point is 2 H lower than the height of the center.
- the wavefront difference in the cross section in the X direction passing through the center of the aberration correcting optical element 4 h is the same as that shown in FIG. is there. That is, when correcting the arrow-shaped aberration shown in FIG. 9A, the aberration correcting optical element 41 ⁇ shown in FIG. 13B is used.
- the height H in FIG. 13 (b) is such that the arrow-shaped aberration shown in FIG. 9 (a) can be completely corrected using the aberration correcting optical element 4 hi, that is, the residual RMS wavefront aberration is ⁇ . It is designed to be.
- the wavefront aberration in the section parallel to the direction inclined 60 ° from the + X direction to the one Y direction passing through the center of the aberration correction optical element 4 h is the wavefront aberration in the section parallel to the X direction passing through the center. Is the same as In addition, the wavefront aberration in a cross section passing through the center of the aberration correcting optical element 4 h and parallel to the direction inclined 60 ° from the + X direction to the + Y direction is the same as the wavefront aberration in the cross section passing through the center and parallel to the X direction. the same It is.
- the arrow-shaped aberration generated in the optical system is at most 0.05 ⁇ as the RMS wavefront aberration.
- four types of aberration correcting optical elements 4h shown in FIGS. 13 (b) to 13 (e) are prepared.
- the amount and sign of the arrow-shaped aberration generated in the optical system from the semiconductor laser 1 to the objective lens 6 excluding the aberration correction optical element 4 h are measured by an interferometer or the like.
- the measured amount and sign of the arrow-shaped aberration are measured by an interferometer or the like.
- one type of aberration correction optical element 4 h is selected as necessary so that the residual RMS wavefront aberration after correction is minimized. Enter. Specifically, when the RMS wavefront aberration is less than or equal to 0.1 ⁇ ⁇ , the correction of the arrow-shaped aberration using the aberration correction optical element 4 h is not performed. When the RMS wavefront aberration is larger than 0.01 ⁇ and smaller than 0.03 ⁇ , the aberration correcting optical element 41 ⁇ shown in Fig. 13 (b) or Fig. 13 (d) depends on the sign of the arrow-shaped difference. arrows aberration correction using the aberration correction optical element 4 h 3 shown to do.
- the arrow-shaped aberration is corrected using the aberration correction optical element 4 h 4 shown in ().
- the residual RMS wavefront aberration after correction can be reduced to 0.01 ⁇ or less.
- four types of aberration correction optical element 4 h are used.However, as the number of types of aberration correction optical element 4 h having different correction amounts and / or signs of the arrow-shaped aberration increases, the residual RMS wavefront aberration after correction becomes smaller. It can be made smaller.
- the direction of the arrow-shaped aberration generated in the optical system is the X direction, the direction inclined 60 ° from the + X direction to one Y direction, and the direction inclined 60 ° from the + X direction to the + Y direction.
- the direction of the arrow-shaped aberration generated in the optical system is the X direction, the direction inclined 60 ° from the + X direction to one Y direction, and the + Y direction from the + X direction.
- the aberration-corrected optical element 4 h is incident on the aberration-corrected optical element 4 h so that the direction substantially matches the direction of the arrow-shaped aberration that can be corrected by the aberration-corrected optical element 4 h. If it is installed by rotating it in a plane perpendicular to the optical axis, the arrow-shaped difference can be corrected.
- any one of the aberration correcting optical elements 4 e, 4 f, 4 g, and 4 h is used, and coma, spherical aberration, astigmatism, and the like generated in the optical system are used.
- any two or more aberration correcting optical elements can be used to correct any two or more aberrations.
- the aberration correction optical element is designed so that the surface of the aberration correction optical element is constituted by a curved surface and the aberration of the optical system can be completely corrected, as compared with the first embodiment described above. Therefore, the aberration of the optical system can be corrected more accurately.
- the design and manufacture of the aberration correction optical element is slightly more difficult than in the first embodiment. The other effects of the present embodiment are the same as those of the above-described first embodiment.
- the optical information recording / reproducing apparatus that performs both recording and reproducing on the disk 7 has been described.
- the present invention is not limited to this, and may be a playback-only device that performs only playback on the disc 7.
- the semiconductor laser 1 is not driven by the semiconductor laser drive circuit 13 based on the recording signal, but is always driven with a constant output.
- the optical information recording / reproducing device is not limited to a DVD drive, and may be a read-only device, and may be a DVD-R (Digital Versatile Disc Recordable: writable). DVD) drive, DVD-ROM (Digital Versatile Disc-Read Only Memory) drive, or DVD—RW (Digital Versatile Disk Rewritable) Or a CD-R (Compact Disc Recordable: writable compact disc) or a CD-ROM (Compact Disk Read Only Memory).
- DVD-R Digital Versatile Disc Recordable: writable
- DVD—RW Digital Versatile Disk Rewritable
- CD-R Compact Disc Recordable: writable compact disc
- CD-ROM Compact Disk Read Only Memory
- the present invention relates to an optical head device for performing recording and / or reproduction on an optical recording medium such as a DVD, a DVD-R, a DVD-ROM, a DVD-RW, a CD-R, and a CD-ROM.
- the present invention relates to a manufacturing method and an optical information recording / reproducing device.
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
Abstract
Description
Claims
Priority Applications (2)
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JP2005506018A JP4241727B2 (ja) | 2003-05-08 | 2004-04-30 | 光ヘッド装置、その製造方法及び光学式情報記録再生装置 |
US10/527,128 US20060007835A1 (en) | 2003-05-08 | 2004-04-30 | Optical head device, method of manufacturing the same, and optical information recording and/or playback apparatus |
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JP2003-130814 | 2003-05-08 | ||
JP2003130814 | 2003-05-08 |
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WO2004100139A1 true WO2004100139A1 (ja) | 2004-11-18 |
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PCT/JP2004/006333 WO2004100139A1 (ja) | 2003-05-08 | 2004-04-30 | 光ヘッド装置、その製造方法及び光学式情報記録再生装置 |
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US (1) | US20060007835A1 (ja) |
JP (1) | JP4241727B2 (ja) |
WO (1) | WO2004100139A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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JPWO2006064735A1 (ja) * | 2004-12-16 | 2008-06-12 | ソニー株式会社 | 光ピックアップ装置及びこの光ピックアップ装置を用いた光ディスク装置並びにその制御方法 |
JP2012068228A (ja) * | 2010-07-30 | 2012-04-05 | Canon Inc | 物体の表面プロファイルを測定する方法及び装置 |
Families Citing this family (2)
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WO2006104206A1 (ja) * | 2005-03-29 | 2006-10-05 | Pioneer Corporation | 収差補正装置、光ピックアップおよび収差補正方法 |
US20100188962A1 (en) * | 2009-01-28 | 2010-07-29 | Panasonic Corporation | Optical Pickup Device and Optical Disk Apparatus Using the Same |
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JPH02218022A (ja) * | 1989-02-17 | 1990-08-30 | Ricoh Co Ltd | 分離型光ピックアップ装置 |
JPH06324281A (ja) * | 1993-05-10 | 1994-11-25 | Ricoh Co Ltd | 光ピックアップ装置 |
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JPS5271253A (en) * | 1975-12-11 | 1977-06-14 | Canon Inc | Compound lens of high resolving power |
US5126994A (en) * | 1988-11-29 | 1992-06-30 | Sony Corporation | Method and apparatus for controlling and detecting recording laser beam |
JP4006032B2 (ja) * | 1995-12-28 | 2007-11-14 | 株式会社日立製作所 | 対物レンズおよび光ヘッド |
US5808999A (en) * | 1996-05-17 | 1998-09-15 | Konica Corporation | Optical pickup apparatus and objective lens for optical pickup apparatus |
JP2910689B2 (ja) * | 1996-06-20 | 1999-06-23 | 日本電気株式会社 | 光ヘッド |
JP3653923B2 (ja) * | 1997-03-19 | 2005-06-02 | ソニー株式会社 | 記録再生装置および方法 |
US6151154A (en) * | 1998-03-12 | 2000-11-21 | Pioneer Electronic Corporation | Optical pickup, aberration correction unit and astigmatism measurement method |
US6967916B2 (en) * | 2000-10-10 | 2005-11-22 | Matsushita Electric Industrial Co., Ltd. | Optical head apparatus, optical information recording and reproducing apparatus, method for detecting aberration and method for adjusting optical head apparatus |
HUP0303190A2 (hu) * | 2000-10-16 | 2003-12-29 | Konica Corporation | Tárgylencse, kapcsoló lencse, fénykonvergáló optikai rendszer és optikai felvevő-lejátszó eszköz |
US6934226B2 (en) * | 2001-04-12 | 2005-08-23 | Matsushita Electric Industrial Co., Ltd. | Optical disk apparatus |
JP2003167187A (ja) * | 2001-06-20 | 2003-06-13 | Konica Corp | 対物レンズ、光ピックアップ装置及び記録・再生装置 |
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2004
- 2004-04-30 US US10/527,128 patent/US20060007835A1/en not_active Abandoned
- 2004-04-30 JP JP2005506018A patent/JP4241727B2/ja not_active Expired - Fee Related
- 2004-04-30 WO PCT/JP2004/006333 patent/WO2004100139A1/ja active Application Filing
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JPH02218022A (ja) * | 1989-02-17 | 1990-08-30 | Ricoh Co Ltd | 分離型光ピックアップ装置 |
JPH06324281A (ja) * | 1993-05-10 | 1994-11-25 | Ricoh Co Ltd | 光ピックアップ装置 |
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JPWO2006064735A1 (ja) * | 2004-12-16 | 2008-06-12 | ソニー株式会社 | 光ピックアップ装置及びこの光ピックアップ装置を用いた光ディスク装置並びにその制御方法 |
JP2012068228A (ja) * | 2010-07-30 | 2012-04-05 | Canon Inc | 物体の表面プロファイルを測定する方法及び装置 |
Also Published As
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JP4241727B2 (ja) | 2009-03-18 |
JPWO2004100139A1 (ja) | 2006-07-13 |
US20060007835A1 (en) | 2006-01-12 |
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