JP2006030845A - Method of manufacturing optical device, optical head device, and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical device having a high optical efficiency, an optical head device, and an optical disk device. <P>SOLUTION: In the method of manufacturing the optical device for forming a diffraction grating pattern for diffracting light on a polymerizable liquid crystal thin film, a substrate, a counter substrate, and projections formed at least on one of the substrates are prepared, and the surface of at least one of the two substrates facing each other is subjected to orientation treatment, and a polymerizable material is disposed and held between the transparent substrates and is hardened, and then one substrate is removed, and a rugged grating is formed on the polymerizable liquid crystal thin film, and an isotropic organic film is disposed on the rugged grating part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention requires regulation of the film thickness of an optical device or a birefringent material bonded with an adhesive for an optical head device used in an optical disk drive device that performs recording, reproduction, erasing, etc. on an information recording medium using a light beam. The present invention relates to a method for manufacturing an optical device.

  As optical recording media, various optical discs such as DVD (digital video disc), CD-R (writeable compact disc), CD-RW (rewritable compact disc) have been developed. In a DVD, information is recorded or reproduced by a laser beam having a wavelength of about 650 nm. On the other hand, in CD-R and CD-RW, information is recorded or reproduced by laser light having a wavelength of about 780 nm. An optical disc apparatus that records or reproduces information on a plurality of types of optical discs has been proposed.

  Further, in such an optical disc drive apparatus that records or reproduces information on a plurality of types of optical discs, a laser element that emits a plurality of light beams having different wavelengths is used as a light source of an optical head device mounted on the optical disc drive apparatus. Are arranged adjacent to one package (so-called hybrid type two-wavelength semiconductor laser), or one in which light sources of a plurality of wavelengths are integrated on one semiconductor substrate (so-called monolithic type two-wavelength semiconductor laser) are used. Yes.

  By combining these units and optical devices, the DVD forward path (condensing system) and return path (detection system) are shared, and the CD and DVD share the collimator lens and objective lens, reducing the number of parts and miniaturization. An optical head device can be provided.

  By the way, as a method for manufacturing the optical device, conventionally, as shown in FIG. 8, an alignment process is formed on at least one of two opposing substrates, and a distance between the substrate 301 and the dummy substrate 302 is constant. The structure is such that the spacer 305 and the polymerizable liquid crystal thin film 304 are held between the liquid crystal film and the liquid crystal film is cured by light irradiation (Patent Document 1).

In addition, there has been a method in which an outer frame portion is formed on at least two sides of the outer peripheral edge of the substrate to make the coating thickness of the polymerizable liquid crystal monomer uniform between the substrates (Patent Document 2).
Japanese Patent Application Laid-Open No. 11-211905 JP 2002-365417 A

  However, as described above (Patent Document 1), according to the method in which the spacer and the polymer liquid crystal film are sandwiched between the opposing substrates to make the substrate interval constant, light is scattered by the spacers, and the transparency is increased. There was a problem to get worse. In addition, the orientation of the polymerizable substance is disturbed due to the influence of the spacer.

  Further, as described above (Patent Document 2), in the method in which the outer peripheral frame is formed on at least two sides of the outer peripheral edge of the substrate and the distance between the substrates is made uniform, the outer peripheral edge is supported by the surface. If accuracy is not ensured with high accuracy, it will affect the accuracy determination of the thickness of the liquid crystal resin, and there has been a problem in improving the yield.

  In order to solve this problem, an optical device manufacturing method according to the present invention includes at least a pair of optical materials provided with a plurality of protrusions on at least one optical material, and a polymerizable substance disposed between the optical materials. The structure which filled and hardened the said polymeric substance is taken.

  According to this configuration, it is possible to provide an optical device that can control the film thickness of the polymerizable substance between the plurality of optical materials and has excellent light transmittance by the protrusions.

  According to the manufacturing method of the present invention, the film thickness of the diffraction grating forming portion can be made uniform by the projections formed with the interval between the transparent substrates, and no material such as a spacer is disposed in the polymerizable liquid crystal portion. Light is not scattered and the light transmission is improved. Furthermore, since the orientation of the polymerizable material is improved, an optical device with high light efficiency can be provided, and an optical head device and an optical drive device with high light efficiency using this element can be provided.

  The method of manufacturing an optical device according to claim 1, wherein at least one pair of optical materials provided with a plurality of protrusions on at least one optical material is arranged to face each other, a polymerizable substance is filled between the optical materials, and the polymerizable property is set. Uses a cured composition.

  According to this method of manufacturing an optical device, it is possible to provide an optical device that can control the film thickness of a polymerizable substance between a plurality of optical materials and has excellent light transmittance by the protrusions.

  The method of manufacturing an optical device according to claim 2 is the method of manufacturing an optical device according to claim 1, wherein the plurality of protrusions are arranged so that gaps between the optical materials are substantially equal over the entire surface of the optical material. The structure is adopted.

  According to this method for manufacturing an optical device, the film thickness of the polymerizable substance can be made uniform over the entire surface of the optical material.

  According to a third aspect of the present invention, there is provided a method for manufacturing an optical device, comprising: performing alignment processing on at least one substrate surface of at least one pair of optical materials provided with a plurality of protrusions on at least one optical material; A method for producing an optical device, wherein a polymerizable substance is filled between optical materials and the polymerizable substance is cured.

  According to such an optical device manufacturing method, an optical device having excellent optical characteristics of a polymerizable substance between a pair of opposing substrates can be provided.

  According to a fourth aspect of the present invention, there is provided a method for producing an optical device according to the third aspect, wherein after the polymerizable substance is cured, one optical material is removed and a diffraction grating is formed on the polymerizable substance. take.

  According to this method of manufacturing an optical device, the distance between the substrates can be made uniform by the restriction by the thickness of the protrusions formed on the substrate, and no material such as a spacer is disposed in the polymerizable liquid crystal part. Is not scattered and the light transmission is improved. Furthermore, since the orientation of the polymerizable substance is improved, an optical device with high light efficiency can be provided.

  According to a fifth aspect of the present invention, there is provided an optical device manufacturing method according to the fourth aspect, wherein the protrusion formed on the substrate is provided in a region other than the diffraction grating pattern forming region.

According to this method of manufacturing an optical device, the protrusions are disposed outside the diffraction grating formation region, thereby eliminating the effects of light efficiency reduction and light scattering caused by the protrusions formed on the substrate.

  The optical device manufacturing method according to claim 6 is the optical device manufacturing method according to claim 4, wherein the shape of the protrusion formed on the substrate is such that the tip of the protrusion is narrower than the base of the protrusion.

  According to such a method for manufacturing an optical device, the tip portion is formed to be narrower than the root of the arranged protrusion, so that the area of the contact portion between the two substrates can be reduced when the transparent substrates are arranged to face each other. It is easy to control the resin thickness of the polymerizable substance.

  The optical device manufacturing method according to claim 7 is the optical device manufacturing method according to claim 4, wherein the thickness of the polymerizable substance is equal to or greater than the height of the protrusion.

  According to such a method for manufacturing an optical device, it is easy to control the weight between two substrates, the thickness of the polymerizable substance can be controlled uniformly, and there is no unevenness in thickness, thereby improving the yield.

An optical device manufacturing method according to an eighth aspect of the invention is the optical device manufacturing method according to the fourth aspect, wherein the density of the protrusions arranged on the substrate is in the range of 0.001 to 1 piece / mm ² .

  According to this method of manufacturing an optical device, it is possible to provide an optical device in which the distance between the opposing substrates can be made uniform, and light transmission and light scattering by the protrusions in the diffraction grating formation region are small.

  An optical head device according to a ninth aspect adopts a configuration using an optical device manufactured by the optical device manufacturing method according to any one of the first to eighth aspects, wherein information is recorded on and reproduced from the optical disk recording medium. .

  According to such a method for manufacturing an optical device, an optical device that has low light scattering, good transparency, and good orientation of the polymerizable substance can be used, and an optical head device with high light utilization efficiency can be provided.

  An optical disk drive apparatus according to a tenth aspect employs a configuration in which the optical head apparatus according to the ninth aspect is used as means for recording information on an optical disk recording medium and reproducing information on the optical disk medium.

  According to this method of manufacturing an optical device, a disk drive device that is compact and has high light utilization efficiency can be provided by using the optical head device according to the ninth aspect.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, components having the same configuration or function and corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

(Embodiment 1)
In FIG. 1, the optical disc drive apparatus 1 includes a housing 2 and a tray 3, and a pickup module 4 and a bezel 5 are configured on the tray 3. FIG. 1 shows a state in which the tray 3 is pulled out from the housing 2. Rails 6 are provided on both sides of the tray 3, and both sides are fitted to the rails 7 so as to be slidable in the disk drawing direction. The rail 7 is also slidably fitted in a disk pull-out direction with rail guides (not shown) provided on the inner surfaces of both sides of the housing 2, and the tray 3 is pulled out from the housing 2 so that the disk can be attached and detached. I can do it. The pickup module 4 is provided with an optical head device 9 constituting an optical system and a spindle motor 4a for rotating the disk. The spindle motor 4a has a disk mounting portion 4b for mounting and rotating the disk.

  FIG. 2 shows an optical head device. The light from the DVD laser 101 is reflected by the surface of the dichroic prism 102, becomes parallel light by the collimating lens 103, passes through the reflection mirror 104, is totally transmitted through the optical device 105, and is ¼ wavelength with respect to a wavelength of 600 to 700 nm. Is converted into circularly polarized light by the quarter-wave plate 106 that gives a phase difference of λ and is focused on the surface of the disk 108 having a substrate thickness of 0.6 mm by the objective lens 107. The light reflected from the disk 108 becomes linearly polarized light orthogonal to the forward path by the quarter-wave plate 106 and is diffracted almost entirely by the optical device 105. The diffracted light is incident on a photodetector (not shown) provided adjacent to the light source, and a signal is detected. On the other hand, the light from the CD laser 110 passes through the glass hologram 111 and the dichroic prism 102 integrated with the integrated unit, passes through the collimating lens 103 and the reflection mirror 104, and passes through the optical device 105 and the quarter wavelength plate 106. To do. The quarter-wave plate 106 has a phase difference of approximately one wavelength with respect to light of 700 to 800 nm, and the polarization of transmitted light does not change in the forward path and the return path. The transmitted light is collected by the objective lens 107 onto the disk surface having a substrate thickness of 1.2 mm. The light reflected from the disk 108 passes through the quarter-wave plate 106 and is totally transmitted without being diffracted by the optical device 105, and is diffracted and branched by the glass hologram 111 along an optical path opposite to the forward path. ) Is detected. In this optical head, a pair of objective lens 107 and collimator lens 103 can deal with light of two wavelengths and disks 108 having different substrate thicknesses.

  FIG. 3 shows an aperture hologram wavelength plate 400 in which the optical device 105, the quarter wavelength plate 204, and the aperture filter 404 are combined. An alignment film 306 is disposed on the surface of the substrate 301, and the quarter wavelength plate 204 is bonded to the optical device 105 formed by the organic film 401 generated by the polymerizable liquid crystal thin film 304 and the isotropic film 402, and the opening is further opened. The filter 404 is arranged and both surfaces of the chip are formed by the AR film 403.

  FIG. 4 shows an example of a method for manufacturing the optical device 105.

  4 (a) and 5 (b) are diffractive elements in which a diffraction grating is provided on the transparent substrate 301 of the present embodiment, and a polymerizable liquid crystal thin film for forming a diffraction grating (hologram pattern). An example of producing is shown below.

As shown in FIG. 4A, a transparent substrate 301 and a dummy substrate 302 are arranged to face each other. The dummy substrate 302 is provided with a convex protrusion 303. The convex protrusions 303 are provided in order to ensure a uniform spacing between the transparent substrate 301 and the dummy substrate 302, and the gap between the substrate 301 and the dummy substrate 302 is made uniform by overlapping. The liquid crystal thin film 304 is set to be uniform. Since the uniform diffraction effect cannot be obtained unless the film thickness of the polymerizable liquid crystal thin film 304 is uniform, the protrusion 303 has a spherical, circular shape in order to make the distance between the transparent substrate 301 and the dummy substrate 302 uniform. Columnar, prismatic, conical, pyramidal, etc. can be selected, but in order to increase the resin thickness regulation accuracy between substrates,
It is desirable that the tip of the protrusion 303 is thin and contacted at a point, such as conical>pyramidal>spherical> planar.

The height of the protrusion 303 is preferably set to be equal to the thickness of the polymerizable liquid crystal thin film 304 or lower than the thickness of the polymerizable liquid crystal thin film 304, and is set to 2 to 5 μm. The transparent substrate 301 and the dummy substrate 302 can be made of glass or a transparent resin such as acrylic or plastic, but a glass material is desirable in terms of strength and durability. Further, if the protrusion 303 is disposed outside the region 309 forming the diffraction grating, the influence on the optical characteristics can be reduced.

  The transparent substrate 301 and the dummy substrate 302 have a thickness of 0.3 to 0.8 mm. An alignment film 306 is formed to adjust the molecular orientation of the polymerizable liquid crystal thin film 304 on the surface in contact with the polymerizable liquid crystal thin film 304 after cleaning with pure water or the like to remove dust and oxide film on the surface of the substrate 301. An alignment process is performed on the alignment film 306.

As a material for the alignment film 306, a polymer film such as a polyimide film or a polyamide film, or SiO ₂ can be used.

  A method of alignment treatment after the formation of the alignment film 306 is shown in FIG. In FIG. 7, a rubbing process is performed in which the alignment film 306 disposed on the transparent substrate 301 is rubbed while the cloth 502 is wound around the roll 501 and rotated.

  Further, as shown in FIG. 4A, the alignment process is also performed on the dummy substrate 302. Since the dummy substrate needs to be removed after the polymerizable liquid crystal thin film 304 is cured, a material 307 having both the peelability and alignment film characteristics is applied.

  Further, the alignment treatment of the substrate 301 and the dummy substrate 302 is more likely to be uniaxial alignment of the liquid crystal molecules when the alignment treatment is performed in the reverse direction of 180 degrees. The direction of the orientation is a direction including the rubbing direction, and the direction is the same for the substrate and the dummy substrate, and the directions are shifted by 180 degrees (anti-parallel).

  When the alignment process is performed, the pressing amount of the cloth 502 during the rubbing process on both the transparent substrate 301 and the dummy substrate 302 is about 100 to 800 μm, so that the dummy substrate 302 has a convex portion. Does not affect the orientation. The pressing amount is desirably 200 to 600 μm. When the thickness is less than 100 μm, the effect of the alignment treatment is reduced. When the thickness is larger than 800 μm, the tip of the protrusion shape may be affected.

  As shown in FIG. 4B, the gap between the orientation-treated transparent substrate 301 and the dummy substrate 302 is obtained by applying a predetermined load to both substrates by means of the projections 303 provided on the dummy substrate 302. Maintain a uniform spacing.

  A polymerizable liquid crystal thin film 304 is applied to the gap between the substrates and is cured by a material curing means for the polymerizable liquid crystal thin film 304 to obtain a polymerizable liquid crystal thin film 304. As a curing means for the polymerizable liquid crystal thin film 304, there is a method using UV light, visible light, laser light, or heating. In this embodiment, the polymerizable liquid crystal thin film 304 is cured by irradiation with UV light having a wavelength of 365 nm.

The dummy substrate 302 of the polymerizable liquid crystal thin film 304 thus manufactured is removed. As shown in FIG. 4C, when the dummy substrate 302 is removed, the polymerizable liquid crystal thin film 304 has a recess 308 due to the effect of the protrusion disposed on the dummy substrate 302. As the number of the concave portions 308 increases, the optical characteristics are affected. Therefore, it is preferable that the number of the concave portions 308 be as small as possible within a range in which the distance between the substrates can be made uniform. In this embodiment, the number of projections 303 maintain the spacing of the opposing substrate 301 and the dummy substrate 302, and in order to improve the light efficiency of the optical device 105, 1 mm ² per 0.001 or so disposed did. If the arrangement is less than 0.001, the uniformity between the pair of substrates cannot be maintained, and the thickness of the polymerizable liquid crystal film becomes non-uniform. If more than one are arranged, light efficiency due to light scattering or the like deteriorates.

FIG. 9 shows the substrate. In the present embodiment, as shown in FIG. 9A, about 256 chips are cut into a 3-inch wafer by dicing or the like. When about 10 convex portions 303 are arranged on about 10 dummy substrates 302 on one wafer, about 10 concave portions 308 corresponding to the polymerizable liquid crystal thin film are also arranged, and about 0.002 pieces per 1 mm ^2. The recess 308 is arranged.

  With such a configuration, an average of about 0.04 recesses 308 are generated per chip of the recesses 308 arranged in one chip, but the generation of the recesses 308 in one chip is at most one, The effect on optical properties can be ignored.

  Further, as shown in FIG. 9B, if the concave portion 308 is disposed outside the diffraction grating formation region, the optical characteristics are not further affected.

  Next, as shown in FIG. 4D, a pattern is transferred to the polymerizable liquid crystal thin film 304 by a photolithography method, and a diffraction grating having a concavo-convex section is formed by a dry etching method, whereby the optical device 105 is formed.

  Next, as shown in FIG. 3, a quarter-wave plate 204 is bonded to the pattern forming unit 401 of the optical device 105 with an isotropic organic film 402.

  Further, the aperture filter 404 is formed on the transparent substrate 310 for forming the aperture filter 404. Thereafter, a member obtained by bonding the optical device 105 and the quarter wavelength plate 204 and the aperture filter 404 are bonded together, and an AR film (antireflection film) 403 is formed on the front and back surfaces to form the aperture hologram wavelength plate 400. .

As a material for the antireflection film, a multilayer film of TiO ₂ / SiO _2, a multilayer film of MgF ₂ / Al ₂ O _{3, and} a multilayer film of TiO ₂ / MgF ₂ / Al ₂ O ₃ / SiO ₂ can be used.

  In the above embodiment, the optical device 105 is formed by forming the projection 303 of the means for uniforming the interval between the opposing substrates on the dummy substrate 302 of the transparent substrate 301 and the dummy substrate 302. As long as the distance between the 301 and the dummy substrate 302 is uniform, as shown in FIG. 5, a projection 303 may be provided on the transparent substrate 301 side.

With this configuration, the protrusion 303 remains in the polymerizable liquid crystal thin film 304 even after the dummy substrate 302 is removed. As the number of protrusions 303 arranged on the transparent substrate 301 increases, the optical characteristics are affected. Therefore, it is preferable to arrange the protrusions 303 as few as possible within a range where the distance between the substrates can be made uniform. In the present embodiment, the number of the protrusions 303 is about 0.001 to 1 per 1 mm ² in order to maintain the distance between the opposing substrate 301 and the dummy substrate 302 and improve the light efficiency of the optical device 105. did. In addition, it is configured to be disposed outside the region 309 of the diffraction grating forming portion as much as possible.

  Further, as shown in FIG. 6, the projection 303 may be provided on the dummy substrate 302 side, the recess 311 on the substrate 301 side may be provided, and the projection 303 and the recess 311 may be assembled together. It is good also as a structure which provides the processus | protrusion 303 to a recessed part by the side of a dummy substrate. According to this configuration, the arrangement accuracy of the protrusions 303 is improved, the optical characteristics are further improved, and the optical device 105 having good diffraction efficiency can be provided.

In the above embodiment, the optical device constituting the diffraction grating has been described. However, the present invention can also be applied to an optical device in which other optical elements are bonded together with an adhesive, for example, an assembly member such as a prism. By adopting this configuration, the interval between the optical devices can be adjusted by the height of the protrusion provided on at least one of the optical materials.

  Further, the thickness of the adhesive can be made uniform, and the refractive index can be made uniform, so that an optical device having good optical characteristics can be provided without adversely affecting the aberration of light.

  Further, even when a birefringent material is arranged as a polymerizable substance, the thickness can be made uniform, so that the retardation value which is one of the factors of the birefringent material becomes uniform.

Retardation = Δn · d
Δn: difference in refractive index between ordinary light and extraordinary light, d: birefringent material thickness

  INDUSTRIAL APPLICABILITY The present invention can be used as an optical head device that records information on an information recording medium using a light beam, reproduces and erases information on the recording medium, and an optical disk drive device using the optical head device. An optical head device and an optical disk drive device with good optical characteristics can be realized.

1 is an external view showing an example of an optical disk drive device according to an embodiment of the present invention. Configuration diagram of an optical head device in an embodiment of the present invention Sectional drawing of aperture hologram wavelength plate in embodiment of this invention Manufacturing process diagram according to an embodiment of the present invention Process drawing of an example of manufacture in another embodiment of the present invention Process drawing of an example of manufacture in another embodiment of the present invention Configuration diagram of orientation processing in an embodiment of the present invention Sectional view of a conventional embodiment The board | substrate figure in embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 Optical head apparatus 105 Optical device 106 1/4 wavelength plate 108a DVD disk 108b CD disk 301 Substrate 302 Dummy substrate 303 Protrusion 304 Polymerizable liquid crystal thin film 305 Spacer 306 Alignment film 307 Peelable alignment film 308 Concave 309 Diffraction grating formation area 400 Aperture Hologram wave plate

Claims (10)

At least one optical material provided with a plurality of protrusions on at least one optical material,
A polymerizable substance is filled between the optical materials,
A method for producing an optical device, wherein the polymerizable substance is cured. 2. The method of manufacturing an optical device according to claim 1, wherein the plurality of protrusions are arranged such that gaps between the optical materials are substantially equal over the entire surface of the optical material. An alignment treatment is performed on at least one substrate surface of at least one pair of substrates, wherein a plurality of protrusions are provided on at least one substrate,
The substrates are arranged opposite to each other,
Between the substrates, filled with a polymerizable material,
A method for producing an optical device, wherein the polymerizable substance is cured. After curing the polymerizable material, one substrate is removed,
4. The method of manufacturing an optical device according to claim 3, wherein a diffraction grating is formed on the polymerizable substance. 5. The method of manufacturing an optical device according to claim 4, wherein the protrusion formed on the substrate is provided outside the diffraction grating formation region. 6. The method of manufacturing an optical device according to claim 1, wherein the protrusion formed on the substrate is formed such that a tip of the protrusion is narrower than a base of the protrusion. 7. The method of manufacturing an optical device according to claim 1, wherein a thickness when the polymerizable substance is arranged is equal to or greater than a height of the protrusion. The density of protrusions that are disposed on the substrate, method of manufacturing an optical device according to claim 7 according to claims 1, characterized in that in the range of 0.001 pieces / mm ^2. 9. An optical head device using an optical device manufactured by the optical device manufacturing method according to claim 1 as means for recording information on an optical disk recording medium and reproducing information on the optical disk medium. 10. An optical disk device using the optical head device according to claim 9 as means for recording information on an optical disk recording medium and reproducing information on the optical disk medium.

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