JP2011076714A - Method of manufacturing optical head device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method of manufacturing an optical head device for correcting aberration at low cost with high accuracy, without enlarging optical components. <P>SOLUTION: In a liquid crystal cell, an unpolymerized and uncured ultraviolet curing liquid crystal monomer to be a polymer liquid crystal layer of a phase correction element is held by at least one pair of transparent substrates including at least one transparent substrate having transparent electrodes on which a pattern for correcting aberration of the phase correction element is formed. The method of manufacturing an optical head device includes: a phase correction element manufacturing process for manufacturing the phase correction element by applying a voltage to the transparent electrodes of the liquid cell and manufacturing the phase correction element by polymerizing and curing the ultraviolet curing liquid crystal monomer of the liquid crystal cell to generate an optimum aberration in the optical head device; a position adjusting process for adjusting the position of the optical head device of the phase correction element manufactured by the phase correction element manufacturing process to optimize the aberration generated in the optical head device; and a phase correction element bonding process for fixing the phase correction element at the adjusted position. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an optical head device that performs recording and / or reproduction (hereinafter simply referred to as “recording and reproduction”) of an optical recording medium (hereinafter referred to as “optical disk”).

  In the optical head device, light of each wavelength is condensed to near the diffraction limit in order to perform recording / reproduction of the optical disk. In order to obtain a focused spot close to the diffraction limit, it is necessary to set the aberration of the optical system to a small value. For this reason, strict accuracy is required for the aberration of each optical component used in the optical head device, and strict accuracy is also required for the arrangement position of each component in the assembly process.

  Aberrations caused by optical head devices include astigmatism and coma caused by optical system misalignment due to errors in optical components and placement position during assembly, and tilting with respect to optical disks. is there. These aberrations have different values depending on the individual optical disk devices due to various factors that occur in the manufacturing process even in optical disk devices having the same optical design. In order to suppress such individual differences in aberration, it is necessary to improve the accuracy of the optical components and to perform precise assembly.

  By the way, as optical disk standards, a plurality of standards such as a CD with a wavelength of 785 nm and a numerical aperture (NA) of 0.45, a DVD with a wavelength of 660 nm and NA of 0.6, and a Blu-ray Disc (BD) with a wavelength of 405 nm and NA of 0.85. Is widely used. In general, when a high NA objective lens such as a BD is used, it is necessary to manufacture and assemble optical components with higher accuracy than when using an NA objective lens such as a DVD or a CD.

  In addition, in order to perform recording / reproduction of optical discs of different standards, there are cases where a plurality of objective lenses are installed in one lens holder. In such a case, when one optical system is adjusted In addition, since the position of the objective lens holder is almost fixed, it is necessary to perform assembly in a state where the position of the objective lens cannot be sufficiently adjusted when adjusting another optical system.

  For example, in such a case, an optical axis shift occurs in another optical system, so that aberrations outside the standard may occur when the light is condensed on the optical disk. In order to suppress such aberration, an example of a method for correcting aberration generated in the assembly process of the optical head device is described in, for example, Patent Document 1 and Patent Document 2.

Japanese Patent No. 2895150 JP 2005-235338 A

S. masuda, T .; Nose and S.M. Sato, "Optical properties of an UV-cured liquid-crystal microlens array", Applied Optics, 1998, Vol. 37, no. 11, p. 2067-2073

  For example, in the method described in Patent Document 1, when a certain amount of aberration is corrected by fixing the position of the optical head device including the aberration correction element, it is necessary to always apply a specific voltage to maintain the alignment of the liquid crystal. There is. For this reason, electrical wiring and drive circuits for driving the liquid crystal elements must be incorporated into the optical components, and a stable voltage is always supplied to keep the optical system large and aberration correction amount constant. There is a problem that the drive circuit becomes complicated to stabilize the supply voltage. Further, when driving a liquid crystal, there is a problem that reliability is lacking because the refractive index variation due to temperature change is large. Although it is possible to incorporate a circuit that compensates for temperature changes, an external temperature sensor is required, which causes problems such as increased costs and complicated circuits.

  In Patent Document 2, when a substance having a polymerization characteristic (polymerizable liquid crystal) is used for an aberration compensation element and the aberration compensation element is incorporated in an optical head device, optimal optical characteristics are expressed at that position. A method of manufacturing an optical head device that controls the alignment of liquid crystal and polymerizes and cures in that state is described. If the method described in Patent Document 2 is used, coma and astigmatism generated in the assembly process can be corrected inexpensively without increasing the size of the optical component. However, Patent Document 2 does not consider the refractive index change caused by the polymerization and curing. That is, even if the optimum condition for aberration correction is obtained before polymerization curing, there is a problem that the aberration cannot be sufficiently suppressed because it deviates from the optimum condition after polymerization curing.

The liquid crystal material has a considerable difference in refractive index and refractive index anisotropy before and after irradiation with ultraviolet light (polymer liquid crystal). For example, FIG. The graph of FIG. 8 shows the result that the retardation value of the liquid crystal cell is greatly different before and after polymerization curing by ultraviolet rays. The retardation value is expressed by the refractive index anisotropy Δn (= | n _e −n _o |) and the thickness (d) of the liquid crystal cell, where n _o is the ordinary light refractive index of the liquid crystal and n _e is the extraordinary light refractive index. (= Δn · d). That is, the change in retardation value is proportional to the change in refractive index anisotropy Δn.

  Since the retardation value of the liquid crystal cell is different as described above, the phase of light transmitted through the liquid crystal cell is also changed. Therefore, when the liquid crystal cell is applied as an aberration correction element, it greatly affects the ability of aberration correction. Therefore, the method of polymerizing and curing simply under the optimum conditions adjusted before polymerization and curing as described in Patent Document 2 does not always provide optimum optical characteristics.

  Accordingly, the present invention provides an aberration including an aberration caused by a deviation (error) from a reference position where each optical component should be arranged in the assembly process at a low cost and with high accuracy without increasing the size of the optical component. An object of the present invention is to provide a method of manufacturing an optical head device capable of correcting the above.

  An aberration correction method according to the present invention includes a light source, an objective lens that condenses light emitted from the light source on an optical disc, a beam splitter that deflects light reflected by the optical disc in a direction different from the light source, and the optical disc. A light detector that detects light reflected by the beam splitter and deflected by the beam splitter; and a high-density liquid crystal monomer formed by polymerizing an ultraviolet curable liquid crystalline monomer disposed in an optical path between the light source and the optical disk. A method of manufacturing an optical head device comprising a phase correction element having a molecular liquid crystal layer, comprising at least one transparent substrate having a transparent electrode on which an aberration correction pattern of the phase correction element is formed. A voltage is applied to the transparent electrode of the liquid crystal cell in which a UV-curable liquid crystalline monomer before polymerization curing, which becomes a polymer liquid crystal layer of the phase correction element, is sandwiched on a transparent substrate. However, a phase correction element manufacturing step for manufacturing the phase correction element by polymerizing and curing an ultraviolet curable liquid crystalline monomer of the liquid crystal cell so that an optimal aberration occurs in the optical head device, and the phase correction element manufacturing A position adjustment step of adjusting the position of the phase correction element manufactured in the process in the optical head device to a position that optimizes the aberration generated in the optical head device, and fixing the phase correction element at the adjusted position. And a phase correction element adhering step.

  According to the present invention, the optical component is increased in size by adopting the method of manufacturing the optical head device that determines the voltage value applied to the phase correction element and the position (alignment) of the phase correction element so as to optimize the aberration. Therefore, it is possible to correct aberrations including aberrations caused by deviation (error) from a reference position where each optical component is to be arranged in the assembly process at low cost and with high accuracy. Furthermore, optimal aberration correction can be performed in consideration of the change in refractive index before and after polymerization curing of the liquid crystal material constituting the liquid crystal layer of the phase correction element.

It is a schematic diagram which shows an example of a structure of the optical head apparatus with which the manufacturing method of this invention is applied. It is a plane schematic diagram which shows an example of the electrode pattern of the astigmatism correction liquid crystal cell 16 '. It is explanatory drawing which shows the example of the magnitude | size of the uncorrected wavefront aberration in the astigmatism correction liquid crystal cell 16 '. It is explanatory drawing which shows the example of the magnitude | size of the wavefront aberration after correction | amendment in the astigmatism correction liquid crystal cell 16 '. It is a plane schematic diagram which shows an example of the electrode pattern of the liquid crystal cell 16 'for coma aberration correction. It is explanatory drawing which shows the example of the magnitude | size of the wavefront aberration in the liquid crystal cell 16 'for coma aberration correction. It is explanatory drawing which shows the other structural example of the liquid crystal cell 16 'for coma aberration correction. It is a block diagram which shows the outline of the manufacturing method of this invention with the processing flow in an assembly process. It is a block diagram which shows an example of the process flow in the assembly process to which the manufacturing method of the optical head apparatus containing a real-time process was applied. It is explanatory drawing for demonstrating the aberration optimal condition extraction process in the aberration correction method which performs superposition | polymerization hardening by a real-time process. It is explanatory drawing for demonstrating the superposition | polymerization hardening process in the aberration correction method which performs superposition | polymerization hardening by a real-time process. It is a block diagram which shows an example of the processing flow in the assembly process to which the manufacturing method of the optical head apparatus containing batch processing was applied. It is explanatory drawing for demonstrating the aberration optimal condition extraction process in the aberration correction method which performs superposition | polymerization hardening by batch processing. It is explanatory drawing for demonstrating the voltage application reproduction-polymerization hardening process in the aberration correction method which performs the polymerization hardening by batch processing. It is explanatory drawing for demonstrating the electrode extraction part cutting process in the aberration correction method which performs superposition | polymerization hardening by batch processing. It is explanatory drawing which shows the other structural example of the optical head apparatus with which the manufacturing method of this invention is applied.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, an example of an optical head device to which the manufacturing method of the present invention is applied will be described with reference to FIG. FIG. 1 is a schematic diagram showing an example of the configuration of an optical head device to which the manufacturing method of the present invention is applied. The optical head device is sometimes called an optical pickup.

  An optical head device 10 shown in FIG. 1 includes a light source 11 that emits light of a predetermined wavelength, a photodetector 15 that detects light, a collimator lens 12 a that converts light from the light source 11 into parallel light, and a light source 11. Light beam (parallel light converted by the collimator lens 12a) is transmitted and guided in the direction of the optical disc 20, and the light (that is, signal light) reflected by the optical disc 20 is deflected and separated to be a photodetector. A beam splitter 13 that guides the light beam from the light source 11 onto the information recording surface of the optical disk 20, and the signal light deflected and separated by the beam splitter 13 is collected on the photodetector 15. A collimator lens 12b, and a phase correction element 16 for correcting aberrations appearing in the light beam from the light source 11.

  The photodetector 15 detects a reproduction signal, a focus error signal, a tracking error signal, and the like, which are information recorded on the information recording surface of the optical disc 20. Although not shown, the optical head device 10 is detected by the focus servo that controls the objective lens 14 in the optical axis direction based on the focus error signal detected by the photodetector 15 and the photodetector 15. And a tracking servo for controlling the objective lens 14 in a direction substantially perpendicular to the optical axis based on the tracking error signal.

  The light source 11 is composed of, for example, a semiconductor laser that emits linearly polarized divergent light in the 650 nm wavelength band. The light emitted from the light source 11 is not limited to the 650 nm wavelength band, and may be a 400 nm wavelength band, a 780 nm wavelength band, or another wavelength band. Here, the 400 nm wavelength band refers to a range of 385 nm to 430 nm. The 650 nm wavelength band refers to a range of 630 nm to 690 nm. The 780 nm wavelength band refers to a range of 760 nm to 800 nm.

  The phase correction element 16 is formed by forming a polymer liquid crystal layer made of polymer liquid crystal between two transparent substrates. As long as the transparent substrate is transparent to incident light, various materials such as a resin plate and a resin film can be used. However, if an optically isotropic material such as glass or quartz glass is used, the transparent substrate can transmit This is preferable because it does not affect the birefringence. Further, it is assumed that a transparent electrode and an alignment film are formed on the transparent electrodes on the opposing surfaces of the two transparent substrates, respectively. A space formed by sealing the two transparent substrates with a sealing material is filled with an ultraviolet curable liquid crystalline monomer, and the filled ultraviolet curable liquid crystalline monomer is subsequently polymerized and cured to form a polymer liquid crystal layer. . Hereinafter, in the method of manufacturing an optical head device of the present invention, an ultraviolet curable liquid crystalline monomer is polymerized and cured with ultraviolet rays to obtain a polymer liquid crystal. An element having a cell (space) made of polymer liquid crystal is referred to as “phase”. The element having a pre-polymerization-curing cell made of an ultraviolet curable liquid crystalline monomer as “correction element (16)” will be described as “liquid crystal cell (16 ′)”.

  For example, the liquid crystal cell may be an astigmatism correction element for correcting astigmatism. FIG. 2 is a schematic plan view showing an example of an electrode pattern of an astigmatism correction liquid crystal cell (hereinafter referred to as an astigmatism correction liquid crystal cell 16 ′) which is an example of the liquid crystal cell 16 ′. FIG. 2 shows an example in which electrodes 201, 202a, 202b, 203a, and 203b are formed in respective regions obtained by dividing the transparent substrate surface into five as transparent electrodes for correcting astigmatism. ing. Although not shown, each electrode is provided with an electrode wiring routed to a terminal provided in the outer peripheral area of the astigmatism correction liquid crystal cell 16 '.

  In this example, each electrode is formed so as to correspond to the phase difference distribution generated by the optical axis shift in the X-axis and Y-axis directions. The electrode 201 is an electrode formed in a circular shape having a diameter smaller than the diameter of the objective lens pupil (broken line in FIG. 2) around the optical axis, and to which a reference voltage is applied. The electrodes 202a and 202b are electrodes for correcting astigmatism generated in the X-axis direction in the radial direction that is the radial direction of the optical disc, and the same electrodes are applied. The electrodes 203a and 203b are electrodes for correcting astigmatism occurring in the Y-axis direction in the radial direction, and the same voltage is applied.

  In order to extract a voltage for optimal aberration correction, the voltage may be applied to each electrode by applying a voltage generated from a power supply to the terminal. At that time, a voltage value to be applied may be controlled using a driving circuit, or may be manually adjusted. Note that the transparent electrode formed on the transparent substrate (not shown) on the side facing the electrode 201 may have an electrode pattern as shown in FIG. 2, but for example, the same voltage (reference voltage) can be applied. An electrode (not divided) may be formed on one surface. For example, the transparent electrode (not shown) is set to one surface ground (GND) level (voltage value = 0 [V]), and control is performed so that different voltages are applied to the respective electrodes shown in FIG.

  The alignment film is formed on the transparent electrode so as to have alignment ability to align liquid crystal molecules so that the abnormal optical axis is in a predetermined direction in a plane parallel to the transparent substrate. The alignment film is formed, for example, by performing a rubbing process on the applied polyimide. In this example, when the incident light is polarized in the X direction (for example, parallel to the X axis), a rubbing process is performed to align liquid crystal molecules so that the abnormal optical axis is in the X direction. To do. The alignment film is not limited to this, and may be formed of an oblique deposition film formed by depositing, for example, SiO as an inorganic material from an oblique direction with respect to the transparent substrate surface.

Next, the principle of astigmatism correction will be described with reference to FIGS. FIG. 3 is an explanatory diagram showing an example of the magnitude (phase difference distribution) of wavefront aberration when aberration correction is not performed. FIG. 4 is an explanatory diagram showing an example of the magnitude (phase difference distribution) of the corrected wavefront aberration. 3A and 4A show the magnitude of wavefront aberration in the XX ′ cross section of FIG. 2, respectively. FIGS. 3B and 4B show the magnitudes of wavefront aberrations in the YY ′ cross section of FIG. 2, respectively. Since astigmatism has an in-plane distribution proportional to x ² -y ² , a positive wavefront aberration occurs in the X-axis direction as shown in FIG. 3A, and FIG. As shown, negative wavefront aberration occurs in the Y-axis direction.

Here, _{V 1} the voltage applied to the electrode 201, _{V 2} the voltage applied to the electrodes 202a and 202b, the voltage applied to the electrodes 203a and 203b and _{V 3.} Further, the refractive index of the liquid crystal with respect to light in the X direction when each voltage is applied to each electrode is n (V). For example, when the liquid crystal is an ultraviolet curable liquid crystalline monomer having a dielectric anisotropy Δε> 0, the major axis direction of the liquid crystal molecules rises in a direction perpendicular to the transparent substrate surface by increasing the voltage. Therefore, the effective refractive index in the X direction becomes smaller. If V ₂ <V ₁ <V ₃ , then n (V ₂ )> n (V ₁ )> n (V ₃ ). In the case of the UV-curable liquid crystalline monomer is a dielectric anisotropy [Delta] [epsilon] _<0, when the _{V 2 <V 1 <V 3} , n (V 2) <n (V 1) <n (V 3) And the inequality sign is reversed. Hereinafter, unless otherwise specified, it is assumed that the monomer is an ultraviolet curable liquid crystalline monomer having a dielectric anisotropy Δε> 0.

  3A and 3B, the broken lines indicate the phase distribution of transmitted light when the voltage of the above relation is applied to each electrode of the astigmatism correction liquid crystal cell 16 ′ of this example. ing. For example, when a voltage having the above relationship is applied, the wavefront of light transmitted through the region where the electrodes 202a and 202b are formed is transmitted through the region where the electrode 201 is formed, as shown by the broken line in FIG. Lags behind the wavefront of the light. In addition, as indicated by a broken line in FIG. 3B, the wavefront of light transmitted through the region where the electrodes 203a and 203b are formed (equal phase) is the wavefront of the light transmitted through the region where the electrode 201 is formed. Go ahead. In this way, by adjusting the voltage value applied to each electrode and changing the phase of the light transmitted through each region, it is possible to give an aberration having a reverse polarity to the original aberration. Then, the wavefront aberration as shown in FIGS. 4A and 4B can be corrected.

  In addition, the liquid crystal cell may be a coma aberration correcting element for correcting coma aberration generated when the objective lens 14 has a tilt (tilt) with respect to the optical disc 20, for example. FIG. 5 is a schematic plan view showing an example of an electrode pattern of a coma aberration correcting liquid crystal cell (hereinafter referred to as coma aberration correcting liquid crystal cell 16 ′) which is an example of the liquid crystal cell 16 ′. FIG. 5 shows an example in which electrodes 301, 302a, 302b, 303a, and 303b are formed in respective regions obtained by dividing the transparent substrate surface into five as transparent electrodes for correcting coma aberration. Yes. Although not shown, each electrode is provided with an electrode wiring routed to a terminal provided in the outer peripheral area of the coma aberration correcting liquid crystal cell 16 '.

  In this example, the five electrodes 301, 302a, 302b, 303a, and 303b are formed in correspondence with the coma aberration distribution generated by the inclination in the X-axis direction of the radial direction with respect to the optical axis direction. Specifically, as shown in FIG. 5, each electrode may be formed in such a shape and position that a phase difference distribution having the same magnitude as the coma aberration distribution and having the opposite sign is generated. In the example illustrated in FIG. 5, a reference voltage is applied to the electrode 301. In addition, the same electrode is applied to the electrodes 302a and 302b. In addition, the same electrode is applied to the electrodes 303a and 303b.

  The voltage may be applied to each electrode by applying a voltage generated from a power source to the terminal as in the case of the astigmatism correcting liquid crystal cell 16 '. At that time, a voltage value to be applied may be controlled using a driving circuit, or may be manually adjusted. Note that the transparent electrode formed on the transparent substrate (not shown) on the side facing the electrode 301 may have an electrode pattern as shown in FIG. 5. For example, the same voltage (reference voltage) can be applied. An electrode (not divided) may be formed on one surface. For example, the transparent electrode (not shown) is set to one surface ground (GND) level (voltage value = 0 [V]), and control is performed so that different voltages are applied to the respective electrodes shown in FIG.

  Similarly, the alignment film is formed on the transparent electrode so as to have alignment ability to align liquid crystal molecules so that the abnormal optical axis is in a predetermined direction in a plane parallel to the transparent substrate. The alignment film is formed, for example, by performing a rubbing process on the applied polyimide. In this example, when the incident light is polarized in the X direction (for example, parallel to the X axis), a rubbing process is performed to align liquid crystal molecules so that the abnormal optical axis is in the X direction. To do. The alignment film is not limited to this, and may be formed of an oblique deposition film formed by depositing, for example, SiO as an inorganic material from an oblique direction with respect to the transparent substrate surface.

Next, the principle of coma aberration correction will be described with reference to FIG. FIG. 6 is an explanatory diagram showing an example of the magnitude (phase difference distribution) of the wavefront aberration in the XX ′ section of FIG. The distribution indicated by the solid line in FIG. 6A indicates the magnitude of wavefront aberration when aberration correction is not performed. FIG. 6B shows the magnitude of the wavefront aberration after correction. The coma aberration has an in-plane distribution proportional to (3r ² −2) x when r ² = x ² + y ^2, and thus a wavefront aberration as shown in FIG. 6A occurs.

Here, _{V 1} the voltage applied to the electrode 301, _{V 2} the voltage applied to the electrodes 302a and 302b, the voltage applied to the electrodes 303a and 303b and _{V 3.} Further, the refractive index of the liquid crystal with respect to light in the X direction when each voltage is applied to each electrode is n (V). By increasing the voltage, the major axis direction of the liquid crystal molecules rises in a direction perpendicular to the transparent substrate surface, so that the effective refractive index in the X direction decreases. If V ₃ <V ₁ <V ₂ , then n (V ₃ )> n (V ₁ )> n (V ₂ ).

  In FIG. 6A, the broken line indicates the phase distribution of the transmitted light when the voltage of the above relation is applied to each electrode of the coma aberration correcting liquid crystal cell 16 'of this example. For example, by applying a voltage of the above relationship, as shown by the broken line in FIG. 6A, the wavefront of light (equal phase) transmitted through the region where the electrodes 302a and 302b are formed is formed by the electrode 301. Proceed with respect to the wavefront of the light that passes through the region. In addition, the wavefront of the light transmitted through the region where the electrodes 303a and 303b are formed is delayed with respect to the wavefront of the light transmitted through the region where the electrode 301 is formed. In this manner, by adjusting the voltage value applied to each electrode and changing the phase in each region, it is possible to give an aberration having a reverse polarity to the original aberration. Then, it is possible to correct the wavefront aberration as shown in FIG.

  Further, the coma aberration correcting liquid crystal cell 16 ′ may have a configuration as shown in FIG. 7, for example. FIG. 7 is an explanatory diagram showing another configuration example of the coma aberration correcting liquid crystal cell 16 ′. FIG. 7A is a schematic plan view of the coma aberration correcting liquid crystal cell 16 ′ of this example, and FIG. 7B is a diagram of the coma aberration correcting liquid crystal cell 16 ′ shown in FIG. It is XX 'sectional drawing.

As shown in FIG. 7, in the coma aberration correcting liquid crystal cell 16 'of this example, a transparent electrode is formed on one of the two transparent substrates 501 and 502, and photolithography and etching are performed thereon. The uneven layer 503 processed into an uneven shape by processing or the like is formed. Note that the uneven layer 503 is formed of an optically isotropic material, and various inorganic materials and organic materials such as a photosensitive resin and a thermosetting resin can be used. As the inorganic material, a SiO _x N _y film (x and y are atomic ratios of O and N to Si), a SiO ₂ film, a Si ₃ N ₄ film, an Al ₂ O ₃ film, etc. can be used. _{The xN y} film is preferably used because it can be adjusted to a desired refractive index by changing x and y depending on the film forming conditions, and is excellent in transparency and durability. Incidentally, the refractive index of the uneven layer 503 and the _{n s.} In addition, an alignment film having an alignment ability for aligning liquid crystal molecules so that the abnormal optical axis is in a predetermined direction in a plane parallel to the transparent substrate is laminated inside the transparent substrates 501 and 502. In this example, if the incident light is polarized in the X direction (for example, parallel to the X axis), a rubbing process for aligning liquid crystal molecules so that the abnormal optical axis is in the X direction with respect to the applied polyimide. It is assumed that an alignment film subjected to is laminated. The alignment film is not limited to this, and may be formed of an oblique deposition film formed by depositing, for example, SiO as an inorganic material from an oblique direction with respect to the transparent substrate surface.

Such transparent substrates 501 and 502 in voids Deki sealed with a sealant, extraordinary refractive index _{n e} and ordinary refractive index _{n e} is _an ultraviolet curable liquid crystal satisfying _{n e>} n _s> n _o The monomer is filled, and the filled ultraviolet curable liquid crystalline monomer 504 ′ is polymerized and cured later to form a polymer liquid crystal layer 504.

The concavo-convex layer 503 formed on the transparent substrate is provided with five regions 401, 402a, 402b, 403a, 403b on the surface of the concavo-convex layer 503 in accordance with the coma distribution generated by the radial inclination with respect to the optical axis. The height of each region is designed as shown in a schematic cross-sectional view in FIG. That is, when the height of the region 401 is d ₁ , the heights of the regions 402a and 402b are d ₂ , and the heights of the regions 403a and 403b are d ₃ , d ₂ > d ₁ > d ₃ , d ₃ = 0 The coma aberration correction function can be realized by setting so that.

  Although not shown, the transparent electrode is provided with an electrode wiring routed to a terminal provided in the outer peripheral area of the coma aberration correcting liquid crystal cell 16 '.

The refractive index of the ultraviolet curable liquid crystalline monomer when the voltage V is applied to the coma aberration correcting liquid crystal cell 16 'of this example is n (V), and the light of wavelength λ incident on the coma aberration correcting liquid crystal cell 16'. in phase of the phase [°] which, based on results at a height _{d 2} and ₁ phase region 401 phi [°], the phase of the regions 402a and 402b phi ₂ [°], regions 403a and 404b of phase Is φ ₃ [°], the phase of the transmitted light in each region is expressed by the following equations.

_{φ 1 = 360 × {d 2} n (V) + d 1 (n s -n (V))} / λ
φ ₂ = 360 × (d ₂ n _s ) / λ
φ ₃ = 360 × (d ₂ n (V)) / λ

Thus, in the voltage range of the n (V)> n _s, for relationship φ _3> φ _1> φ ₂ is satisfied, the phase difference occurs between the light passing through the respective regions. Then, the wavefront of the light transmitted through the regions 402a and 402b (equal phase) travels with respect to the wavefront of the light transmitted through the region 401. In addition, the wavefront of the light transmitted through the regions 403a and 403b is delayed with respect to the wavefront of the light transmitted through the region 401. In this way, by adjusting the voltage value applied to the transparent electrode and changing the phase in each region, it is possible to give an aberration of opposite polarity to the original aberration, so that the coma aberration can be corrected. .

  In the above example, the case where an astigmatism correction liquid crystal cell and a coma aberration correction liquid crystal cell are realized as an example of the liquid crystal cell 16 ′ has been described. For example, two liquid crystal cells sandwiching one liquid crystal cell are used. Of the transparent electrodes, an electrode pattern for correcting astigmatism may be formed on one surface, and an electrode pattern for correcting coma aberration may be formed on the other surface. Further, the above-described astigmatism correction liquid crystal cell and coma aberration correction liquid crystal cell may be laminated, and further have a ring electrode region pattern concentrically around the optical axis. There may be one that corrects spherical aberration. In this way, it is possible to realize an element that corrects two or more types of aberrations by one element.

  In the example shown in FIG. 1, an example in which the phase correction element 16 is installed in the optical path between the collimator lens 12 a and the beam splitter 13 is shown, but not limited thereto, at least the phase correction element 16 includes the light source 11. As long as it is disposed in the optical path until the light beam from is collected on the optical disc 20. For example, it may be disposed in the optical path between the beam splitter 13 and the objective lens 14.

  By the way, when such a liquid crystal cell is incorporated in an optical head device, if the liquid crystal cell itself or a reference position (optical axis) where other optical components are arranged is displaced or tilted with respect to the optical axis, The phase difference distribution in the liquid crystal cell may deviate from the wavefront aberration distribution to be corrected. In such a case, the voltage value applied to each electrode may be further adjusted according to the shift width.

  In the present invention, in an assembly process when manufacturing an optical head device, a voltage value applied to each electrode of the liquid crystal cell is determined in consideration of an error in aberration generated for each optical head device. At this time, it is determined based on the change in the retardation value of the liquid crystal generated by irradiating with ultraviolet rays for polymerization and curing. Then, in a state where a voltage value determined so as to express optimum optical characteristics is applied, the liquid crystal monomer is polymerized and cured by irradiating with ultraviolet rays, and is incorporated into the optical head device as an aberration phase element.

In addition, as a material of the polymerizable liquid crystal, a substance that does not cause a change in the refractive index anisotropy Δn before and after the polymerization curing may be used. In this case, for example, a connecting chain of a polymer group such as acrylic and a mesogen group (liquid crystal molecule) having a variation rate of Δn before and after polymerization curing of 30% or less is preferable. In addition, what becomes 20% or less is more preferable, and if it is 10% or less, it is still more preferable. For example, a methylene chain or an oxyethylene chain may be used. More specifically, a methylene chain “(CH 2) _n ” (n = 2 to 8, preferably about 4 to 6) may be used.

  Next, a method for manufacturing the optical head device of the present invention will be described. FIG. 8 is a block diagram showing an outline of the manufacturing method of the present invention in a process flow in an assembly process. As shown in FIG. 8, the manufacturing method of the optical head device of the present invention includes a voltage distribution extraction step, a polymerization curing step, and a position adjustment step.

  In the voltage distribution extraction step, the voltage distribution to be extracted in a state where the optical axis positions of the liquid crystal cell 16 ′ having a cell before polymerization curing made of an ultraviolet curable liquid crystalline monomer and the series of optical components are physically aligned is The voltage distribution of the liquid crystal cell 16 ′ that optimizes the aberration caused by the deviation of the optical axis of a series of optical components constituting the optical head device (more specifically, for aberration correction provided in the liquid crystal cell 16 ′) The voltage distribution applied to the transparent electrode is extracted. It is preferable that the optical components other than the liquid crystal cell 16 'are fixed and bonded in a state where the optical axis positions are physically determined because the aberration component to be corrected by the liquid crystal cell 16' does not change. At this time, the liquid crystal cell 16 ′ is temporarily secured at the optical axis position.

  In the voltage distribution extraction step, for example, the voltage value applied to the aberration-correcting transparent electrode provided in the liquid crystal cell 16 ′ in a state where the optical axis is aligned is changed and the liquid crystal cell 16 ′ that has passed through the liquid crystal cell 16 ′ is transmitted. You may extract by specifying the voltage distribution from which an aberration characteristic becomes the best from the result of measuring the aberration which expresses in emitted light. Further, for example, based on the tendency of the refractive index change before and after the polymerization curing of the liquid crystal material used in the liquid crystal cell 16 ′ that has been detected in advance, an optimum aberration is exhibited by the phase correction element 16 after the polymerization curing. You may extract by calculating the voltage distribution which becomes.

  In the polymerization curing step, the voltage extracted as the optimum voltage distribution in the voltage distribution extraction step is applied to the liquid crystal cell 16 ′ which is the phase correction element 16 disposed in the optical head device, and the liquid crystal is applied in a state where the voltage is applied. The phase correction element 16 is produced by polymerizing and curing the ultraviolet curable liquid crystalline monomer by irradiating the cell 16 ′ with ultraviolet rays.

  In the position adjustment step, the produced phase correction element 16 is used to measure the manifestation of the emitted light that has passed through the phase correction element 16, and the position (tilt) of the phase correction element 16 that optimizes the aberration is determined. Adjust). Then, the phase correction element 16 is fixed at the adjusted position. In the position adjustment step, the phase can be corrected more strictly by adjusting the position when the voltage distribution extraction step extracts a voltage distribution that will exhibit optimal aberrations after polymerization and curing. .

  Note that a voltage distribution information recording step of storing the information of the voltage distribution extracted in the voltage distribution extraction step in the storage device may be included between the voltage distribution extraction step and the polymerization curing step. In such a case, in the polymerization curing process, based on the stored voltage distribution information, the voltage application under the optimum condition is reproduced at a different location not incorporated in the optical head device with respect to the liquid crystal cell 16 ′. The correction element 16 may be manufactured. Further, it may include an optical axis alignment step after polymerization curing in which the phase correction element 16 produced after the polymerization curing step is physically aligned with the position of the optical axis of a series of optical components incorporated in the optical head device. .

  Further, in the voltage distribution extraction step, a voltage distribution extraction liquid crystal cell capable of obtaining the same characteristics as the liquid crystal cell 16 ′ serving as the phase correction element 16 incorporated in the optical head device was extracted from the voltage distribution extraction liquid crystal cell. Information on the voltage distribution may be information on the voltage distribution of the liquid crystal cell 16 ′. Further, in the polymerization curing step, a plurality of phase correction elements 16 may be produced by reproducing voltage application under optimum conditions individually for the plurality of liquid crystal cells 16 ′.

  Hereinafter, the method for manufacturing the optical head device of the present invention will be described more specifically. In the present invention, “real time processing” and “batch processing” are defined and described below. In the “real time processing”, adjustment of aberration correction conditions (liquid crystal superposition) of the liquid crystal cell 16 ′ serving as the phase correction element 16 and integration as the phase correction element 16 are consistently performed for each optical head device 10. Refers to processing. On the other hand, in the “batch processing”, polymerization of each liquid crystal cell 16 ′, which is arranged in one or more optical head devices 10 and becomes one or more phase correction elements 16 having different aberration correction conditions, is separated in one process. This process is performed collectively at the location.

1. Method for Manufacturing Optical Head Device Including Real-Time Processing First, a method for manufacturing an optical head device that performs polymerization and curing in real time on an ultraviolet curable liquid crystalline monomer of a liquid crystal cell will be described. The manufacturing method of the optical head device of the present invention is executed in an assembly process in which the production of other optical components is completed and assembled. FIG. 9 is a block diagram illustrating an example of a processing flow in an assembling process to which an optical head device manufacturing method including real-time processing is applied. As shown in FIG. 9, in the optical head device manufacturing method including real-time processing, in the assembly process, first, the optical axis of the liquid crystal cell 16 ′ is aligned with the other optical components already aligned and bonded. The liquid crystal cell 16 'is fixed at the position (first step: optical axis alignment step). In the case of the optical head device shown in FIG. 1, it is arranged and bonded in accordance with the optical axis from the light source 11 with respect to other optical components such as the objective lens 14, the beam splitter 13, and the collimator lenses 12a and 12b except for the liquid crystal cell 16 ′. After that (the last optical component), the position of the liquid crystal cell 16 ′ is physically adjusted to align the optical axis of the liquid crystal cell 16 ′.

  Next, the voltage distribution applied to the liquid crystal cell 16 ′ is set as a condition for performing beam irradiation in a state where the liquid crystal cell 16 ′ is temporarily fixed without using an adhesive at a position aligned with the optical axis and optimizing the aberration. Extract (second process: aberration optimum condition extraction process). Here, the voltage value applied to the electrode (electrode for aberration correction) of the liquid crystal cell 16 ′ is changed as needed, and a combination of voltage values with the smallest aberration is extracted. For example, in a state where the other optical components and the liquid crystal cell 16 ′ are combined, beam irradiation is performed from the light source 11, and the emitted light transmitted through the liquid crystal cell 16 ′ is positioned at a position to be an information recording surface of the optical disk to be collected. A laser interferometer is placed and the voltage value is changed while measuring the observed aberration to identify the voltage distribution with the best aberration characteristics. For example, as shown in FIG. 10, voltage application and voltage value adjustment are performed by electrically connecting the terminal of the voltage control device to the terminal of the electrode wiring routed to the electrode of the liquid crystal cell 16 ′. This can be done by changing the voltage level of the device.

  Next, the ultraviolet curable liquid crystalline monomer of the liquid crystal cell 16 ′ is polymerized and cured in a state where the voltage of the optimum condition extracted in the previous step is applied to the electrode of the liquid crystal cell 16 ′ (third process: polymerization curing process). At this time, ultraviolet rays are irradiated while applying the optimum voltage to the electrodes of the liquid crystal cell 16 ', and the voltage value is maintained until the curing is completed (see FIG. 11). By this step, the liquid crystal cell 16 ′ becomes the phase correction element 16 including the polymer liquid crystal. Further, after the completion of this process, the connection of the electrical wiring with the voltage control device connected to the phase correction element 16 is released.

  Next, as a condition for optimizing the aberration again, a position (including an angle or the like) at which the phase correction element 16 produced by polymerization hardening is arranged is extracted (fourth step: aberration optimum condition extraction step (position adjustment)). ). Here, in consideration of a change in the refractive index anisotropy Δn of the liquid crystal before and after the polymerization curing, the position where the phase correction element 16 after the polymerization curing is arranged is adjusted again to minimize the aberration. Determine the position. For example, the emitted light from the phase correction element 16 may be measured using a laser interferometer, and the position may be finely adjusted based on the measured value so that the aberration characteristics are the best.

  Finally, the phase correction element 16 is bonded at the position of the optimum condition extracted in the previous process (fifth process: phase correction element bonding process). Here, the phase correction element 16 is arranged and bonded to the position extracted in the fourth step. For example, the phase correction element 16 may be bonded to a joint portion with another optical component or frame provided for the phase correction element 16.

  In the second step, the voltage distribution to be applied to the liquid crystal cell 16 ′ may be extracted based on the characteristics of the liquid crystal material used so that the aberration correction characteristics become the optimum conditions after polymerization and curing. For example, grasp the tendency (change width) of refractive index change before and after polymerization curing of the liquid crystal material to be used in advance, and consider the tendency of refractive index change based on the result measured in the state before polymerization curing. A voltage condition at which the aberration is optimal after curing may be determined. Even when the voltage condition at which the aberration is optimal after the polymerization curing is determined in the second step, the position of the phase correction element 16 including the polymer cured polymer liquid crystal is adjusted in the fourth step. Aberration can be corrected with high accuracy. In addition, when a material that does not cause a change in the value of refractive index anisotropy Δn before and after polymerization curing is used as a material for the polymerizable liquid crystal, polymerization curing and adhesion are performed as they are under the optimum conditions before polymerization curing. It is also possible to make it.

2. Method for Manufacturing Optical Head Device Including Batch Processing Next, a method for manufacturing an optical head device including a step of performing polymerization and curing by batch processing will be described. FIG. 12 is a block diagram illustrating an example of a processing flow in an assembling process to which an optical head device manufacturing method including real-time processing is applied. As shown in FIG. 12, the first step and the second step are the same as in the case of performing polymerization and curing by real-time processing. Even in the case of performing the polymerization and curing by batch processing, in the second step, based on the measured value before the polymerization and the tendency of the refractive index change so that the aberration correction characteristic becomes the optimum condition after the polymerization and curing. The voltage distribution applied to the liquid crystal cell 16 ′ may be extracted.

  Further, in the method of manufacturing an optical head device including the step of performing polymerization and curing by batch processing, after extracting the voltage value as the optimum condition, the extracted voltage value is stored in a separately provided storage device (see FIG. 13). . For example, the voltage value applied to each electrode of the liquid crystal cell 16 ′ extracted as the optimum condition for the individual phase correction element 16 incorporated in the individual optical head device is used as an identifier (lot number) for identifying the phase correction element 16 Etc.) and stored in the storage device. In the present manufacturing method, after the second step is completed, the liquid crystal cell 16 'is temporarily removed.

  Note that the voltage distribution extraction in the batch processing may employ a method that does not use the liquid crystal cell 16 ′ at the previous stage, which is finally arranged as the phase correction element 16. That is, a voltage distribution extraction liquid crystal cell (not shown) having the same optical characteristics as the liquid crystal cell 16 ′ is prepared, and the voltage distribution information extracted from the voltage distribution extraction liquid crystal cell is finally arranged as the phase correction element 16. The voltage distribution of the liquid crystal cell 16 ′ at the stage is obtained. In this way, for example, information on the voltage distribution of the liquid crystal cells 16 ′ of a plurality of optical head devices can be obtained by one voltage distribution extraction liquid crystal cell, and efficiency can be improved. Since the liquid crystal cell for voltage distribution extraction does not need to be cured by ultraviolet rays, the liquid crystal material is not necessarily limited to the ultraviolet curable liquid crystalline monomer as long as it has the same optical characteristics as the liquid crystal cell 16 ′, and other ultraviolet curing agents. A structure using an incompatible liquid crystal material may be used.

  In the next third step, for example, as shown in FIG. 14, each liquid crystal cell 16 ′ in the previous stage finally arranged as the phase correction element 16 is connected to a unitary voltage control device (multi-probe). The voltage application under the optimum conditions extracted in the previous process is reproduced for each. Then, the ultraviolet curable liquid crystalline monomer of each liquid crystal cell 16 ′ is polymerized and cured in a state where the voltage application under the optimum conditions is reproduced (third process: voltage application reproduction—polymerization curing process). At this time, it is only necessary to irradiate the liquid crystal cell 16 ′ with the ultraviolet rays while applying the optimum voltage to the electrodes and maintain the voltage value until the curing is completed. By this step, each liquid crystal cell 16 ′ becomes a phase correction element 16 including a polymer liquid crystal polymerized and cured. Further, after the third step is completed, the connection of the electrical wiring with the voltage control device connected to each phase correction element 16 is released. In addition, although the aspect which has the multiprobe which can apply a voltage to the several liquid crystal cell 16 in the voltage control apparatus was demonstrated in FIG. 14, it is not restricted to this, For example, it is electric with respect to one liquid crystal cell 16 '(only). Using a voltage control device that performs wiring, a process of applying voltage by applying electrical connection to each liquid crystal cell 16 ′, and detaching and wiring the electrical wiring, may be repeated.

  As described above, in the batch processing, the polymerization and curing can be performed without being incorporated in the optical head device, so that the plurality of phase correction elements 16 can be manufactured collectively. Furthermore, in the batch processing, the ultraviolet light that becomes the stray light leaks to the other optical components of the optical head device is not irradiated, and the change in the optical characteristics of the other optical components due to the ultraviolet irradiation can be suppressed. Further, in the method of manufacturing an optical head device including a step of performing polymerization and curing by batch processing in particular, as shown in FIG. 15, the step of cutting the electrode lead-out portion 61 of each phase correction element 16 after the electrical wiring connection is released is included. May be. This process can realize further downsizing of the optical head device.

  Finally, each phase correction element 16 produced by polymerization and curing is incorporated into the optical head device (fourth step: phase correction element loading step). For example, each phase correction element 16 may be fixed in position and bonded to the optical head device that has been aligned in the first step based on the stored lot number. As an alignment method in the fourth step, for example, the position where the liquid crystal cell 16 ′ in the previous stage of the phase correction element 16 is fixed in the first step is stored as a numerical value (alignment value or the like), and the position is stored at that position. You may combine them. In such a case, a material that does not cause a change in refractive index anisotropy Δn before and after polymerization curing is used as a material for the polymerizable liquid crystal, or measurement before polymerization curing is performed in the second step. It is assumed that a voltage distribution that is the optimum condition after polymerization and curing is extracted based on the value and the tendency of refractive index change.

  As a method for aligning the phase correction element 16, for example, the light irradiation from the light source 11 is performed, and the aberration of the emitted light transmitted through the phase correction element 16 is measured with a laser interferometer. The position may be adjusted. The adjustment of the phase correction element 16 to the optimum position may be performed when the phase correction element 16 is fixed in accordance with the fixing position of the liquid crystal cell 16 ′ in the first stage in the first step.

  Thus, according to the present invention, aberrations including individual aberrations that occur when the optical head device is assembled can be corrected with high accuracy. In addition, since it is not necessary to incorporate a drive circuit or the like for dynamically driving the voltage of the liquid crystal at all times in order to individually adjust the correction amount of aberration, it can be manufactured at a low cost without increasing the size.

  In the above example, the optical head device 10 in which one objective lens is installed in one lens holder has been described as an example. However, the present invention is a light having two optical systems as shown in FIG. 16, for example. The present invention can also be applied to a head device.

  An optical head device 200 shown in FIG. 16 performs recording / reproduction of an optical disc of a plurality of standards, and has two optical systems 30 and 40 corresponding to the respective standards. As in the optical head device 10 shown in FIG. 1, each optical system includes a light source (light source 31 or 41) that emits light of a predetermined wavelength and a light detector (light detector 35 or 41) that detects light. 45), a collimator lens (collimator lens 32a or 42a) for converting the light from the light source into parallel light, and the light beam emitted from the light source emitted from the collimator lens is transmitted and guided in the direction of the optical disk 20, and the optical disk 20 A beam splitter (beam splitter 33 or 43) for deflecting and separating the signal light reflected from the light and guiding it in the direction of the photodetector, and an objective lens (objective lens) for condensing the beam from the light source on the information recording surface of the optical disc 20 34 or 44) and a collimator lens (collimator lens) that condenses the signal light deflected and separated by the beam splitter onto a photodetector. 2b or 42b) and is included. The objective lens 34 of the optical system 30 and the objective lens 40 of the optical system 40 are fixed by a common lens holder 51.

  In the example illustrated in FIG. 16, an example in which the phase correction element 46 is included only in the optical system 40 is illustrated. The phase correction element 46 is an element corresponding to the phase correction element 16 in FIG. The optical system 30 may also include a phase correction element corresponding to the phase correction element 16 in FIG.

  The optical head device 200 shown in FIG. 16 detects, for example, the type of the optical disc 20 when recording / reproducing the optical disc 20, and switches between using the optical system 30 or the optical system 40 depending on the type. And

  In the case of such an optical head device, assembly is first performed from one optical system (for example, the optical system 30). At that time, the arrangement position is precisely adjusted so that each optical component constituting the optical system does not have an optical axis shift or inclination. At this time, the lens holder 51 is fixed. Next, the other optical system (for example, the optical system 40) is assembled. Since the position of the lens holder 51 for fixing the objective lens of the optical system is already fixed, the objective stored in the lens holder 51 is used. The lens may have an inclination (angle shift) with respect to the optical axis of the optical system. For example, coma generated due to this inclination is corrected by the phase correction element 46 for correcting coma.

  Specifically, as in the above-described process example, in the assembly process when manufacturing the optical head device, the aberration generated for each optical head device and the tendency of the refractive index change of the liquid crystal material before and after polymerization curing Is determined based on the voltage value to be applied to each electrode of the liquid crystal cell 16 ′ to be the phase correction element 46 and the arrangement position of the liquid crystal cell 16 ′ or the phase correction element 46 after polymerization curing, and according to the voltage value and the arrangement position. The ultraviolet curable liquid crystalline monomer of the liquid crystal cell 16 ′ may be polymerized and cured, or the liquid crystal cell 16 ′ or the phase correction element 46 after polymerization and curing may be fixed (adhered).

  In the above embodiment, the characteristic configuration of the method of manufacturing the optical head device as shown in the following supplementary notes 1 to 3 is shown.

  (Supplementary Note 1) A light source, an objective lens for condensing light emitted from the light source on an optical disc, a beam splitter for deflecting light reflected by the optical disc in a different direction from the light source, and reflected by the optical disc A photodetector for detecting light deflected by the beam splitter; and a polymer liquid crystal layer formed by polymerizing an ultraviolet curable liquid crystalline monomer disposed in an optical path between the light source and the optical disc. A method of manufacturing an optical head device comprising a phase correction element having at least a pair of transparent substrates including at least one transparent substrate having a transparent electrode on which an aberration correction pattern of the phase correction element is formed. While applying a voltage to a transparent electrode of a liquid crystal cell sandwiching an ultraviolet curable liquid crystalline monomer before polymerization curing, which becomes a polymer liquid crystal layer of a phase correction element, the optical head The phase correction element creating step for producing the phase correction element by polymerizing and curing the ultraviolet curable liquid crystalline monomer of the liquid crystal cell so that the optimum aberration occurs in the position, and the phase correction element creating step, A position adjustment step of adjusting the position of the phase correction element in the optical head device to a position that optimizes the aberration generated in the optical head device, and a phase correction element adhesion step of fixing the phase correction element at the adjusted position And a method of manufacturing an optical head device.

  (Appendix 2) A light source, an objective lens for condensing the light emitted from the light source on the optical disc, a beam splitter for deflecting the light reflected by the optical disc in a different direction from the light source, and reflected by the optical disc A photodetector for detecting light deflected by the beam splitter; and a polymer liquid crystal layer formed by polymerizing an ultraviolet curable liquid crystalline monomer disposed in an optical path between the light source and the optical disc. A method of manufacturing an optical head device comprising a phase correction element having at least a pair of transparent substrates including at least one transparent substrate having a transparent electrode on which an aberration correction pattern of the phase correction element is formed. While applying a voltage to the transparent electrode of the liquid crystal cell sandwiching the ultraviolet curable liquid crystalline monomer before polymerization curing that becomes the polymer liquid crystal layer of the phase correction element, A series of aberrations appearing in the light transmitted through the phase correction element when the external-curing liquid crystalline monomer is polymerized and cured to form the phase correction element, constituting the optical head device excluding the phase correction element The phase correction element is produced by polymerizing and curing the ultraviolet curable liquid crystalline monomer of the liquid crystal cell after optimizing the voltage value so as to correct the amount of aberration generated in the optical head device composed of the above optical components. A phase correction element creation step, and a position adjustment step of adjusting the position of the phase correction element produced in the phase correction element creation step in the optical head device to a position that optimizes the aberration generated in the optical head device; A phase correction element adhering step of fixing the phase correction element at the adjusted position.

  (Supplementary Note 3) A light source, an objective lens for condensing light emitted from the light source onto an optical disc, a beam splitter for deflecting light reflected by the optical disc in a direction different from the light source, and reflected by the optical disc A photodetector for detecting light deflected by the beam splitter; and a polymer liquid crystal layer formed by polymerizing an ultraviolet curable liquid crystalline monomer disposed in an optical path between the light source and the optical disc. A method of manufacturing an optical head device having a phase correction element having the phase correction element in consideration of aberration errors occurring in the optical head device in an assembly process when manufacturing the optical head device. Including at least one transparent substrate having a transparent electrode on which an aberration correction pattern of the phase correction element is formed so that an aberration of an optical head device including the optical head device may obtain an optimum value Generated by irradiating the transparent electrode of the liquid crystal cell, which is the polymer liquid crystal layer of the phase correction element before polymerization curing between the pair of transparent substrates, with ultraviolet light for polymerization curing In the state where the voltage value based on the change in the retardation value of the liquid crystal is applied, the phase correction element obtained by polymerizing and curing the liquid crystalline monomer by irradiating ultraviolet rays is a position that optimizes the aberration generated in the optical head device. A method of manufacturing an optical head device, comprising: a phase correction element bonding step for fixing to the optical head device, wherein the phase correction element is incorporated into the optical head device by the phase correction element bonding step.

  The present invention can be suitably applied to applications that correct aberrations that occur in an optical system device that achieves some purpose by combining optical components, such as an optical head device that performs recording and reproduction on an optical disk.

DESCRIPTION OF SYMBOLS 10, 200 Optical head apparatus 20 Optical disk 30, 40 Optical system 11, 31, 41 Light source 12a, 12b, 32a, 32b, 42a, 42b Collimator lens 13, 33, 43 Beam splitter 14, 34, 44 Objective lens 15, 35, 45 Photodetector 16, 46 Phase correction element (astigmatism correction element, coma aberration correction element)
16 'liquid crystal cell (astigmatism correction liquid crystal cell, coma aberration correction liquid crystal cell)
51 Lens holder 61 Electrode lead-out portion 201, 202a, 202b, 203a, 203b Aberration correction transparent electrode 301, 302a, 302b, 303a, 303b Aberration correction transparent electrode 401, 402a, 402b, 403a, 403b Aberration correction Divided regions 501, 502 Transparent substrate 503 Concavity and convexity layer 504 Polymer liquid crystal layer 504 ′ UV curable liquid crystalline monomer

Claims (1)

A light source, an objective lens for condensing the light emitted from the light source on the optical disc, a beam splitter for deflecting the light reflected by the optical disc in a direction different from the light source, and reflected by the optical disc by the beam splitter. A phase correction element having a photodetector for detecting deflected light and a polymer liquid crystal layer formed by polymerizing an ultraviolet curable liquid crystalline monomer disposed in an optical path between the light source and the optical disk An optical head device manufacturing method comprising:
An ultraviolet curable liquid crystal before polymerization and curing which becomes a polymer liquid crystal layer of the phase correction element on at least one pair of transparent substrates including at least one transparent substrate having a transparent electrode on which an aberration correction pattern of the phase correction element is formed. While applying a voltage to the transparent electrode of the liquid crystal cell sandwiching the polymerizable monomer, the phase-correcting element is obtained by polymerizing and curing the ultraviolet curable liquid crystalline monomer of the liquid crystal cell so that an optimum aberration occurs in the optical head device. A phase correction element manufacturing process for manufacturing
A position adjustment step of adjusting the position of the phase correction element produced in the phase correction element production step in the optical head device to a position that optimizes the aberration generated in the optical head device;
And a phase correction element adhering step of fixing the phase correction element at the adjusted position.

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