JP2006053992A - Optical pickup device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup miniaturized by miniaturizing an optical element constituting an optical pickup device. <P>SOLUTION: This optical pickup device is capable of either recording or reproducing information in an optical information recording medium and provided with a light source 11 for emitting an optical beam, and a plurality of optical elements (e.g., polarized beam splitter 13, a 1/4 wavelength plate 14, an objective lens 15, and collimator lens 19). At least one of the optical elements includes a translucent DLC film including the local area of a relatively high refraction index and the local area of a relatively low refractive index. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pickup device capable of at least one of recording and reproducing information on an optical information recording medium, and a method for manufacturing the same.

  In an optical pickup device used for recording and reproducing information on an optical information recording medium such as a CD (Compact Disk) and a DVD (Digital Video Disk), a light beam from a light source is used as an information recording surface of the optical information recording medium. In order to collect the light reflected on the information recording surface and the light receiving unit, various optical elements such as a light emitting element, a polarizing beam splitter, a quarter wavelength plate, an objective lens, a focusing lens, and a light receiving element are used. An element is used (for example, see Patent Document 1).

  Here, in an optical element such as a polarizing beam splitter, a quarter-wave plate, an objective lens, and a focusing lens, a relief type (film thickness modulation type) diffraction grating is used to refract light. For example, in Patent Document 1, a lens (relief type lens) on which a relief type diffraction grating is formed as shown in FIG. 12 is used as an objective lens.

  However, the relief lens as described above, as shown in FIG. 12, modulates the thickness of the lens film, for example, regularly modulates the film thickness concentrically, and diffracted light by the light diffraction action. Since the light (such as the first-order diffracted light 121 and the second-order diffracted light 122) is condensed like a convex lens, there is a problem that the manufacturing process is difficult and other members cannot be laminated on the lens.

  Further, since the conventional polarizing beam splitter is composed of two microprisms and has a thickness of 3 mm or more, it is difficult to further reduce the size.

  Further, since a quartz plate having a thickness of 0.5 mm or more is used for the conventional quarter-wave plate, it is difficult to further reduce the size.

Therefore, there has been a limitation on the miniaturization and / or integration of the optical elements constituting the optical pickup device, and it has been difficult to miniaturize the optical pickup device.
JP 2003-66324 A

  An object of the present invention is to provide an optical pickup device that is miniaturized by downsizing and / or integrating optical elements that constitute the optical pickup device.

  The present invention is an optical pickup device capable of at least one of recording and reproduction of information on an optical information recording medium, including a light source that emits a light beam and a plurality of optical elements that control the light beam. At least one of the elements is an optical pickup device including a translucent DLC film including a local region having a relatively high refractive index and a local region having a relatively low refractive index.

  In the optical pickup device according to the present invention, the optical element including the DLC film can be a polarizing beam splitter, a quarter wavelength plate, an objective lens, a focusing lens, and / or a collimator lens.

  In addition, the present invention is a method for manufacturing the above-described optical pickup device, and is a method for manufacturing an optical pickup device in which a relatively high refractive index region in a DLC film is formed by irradiation with an energy beam. .

  In the method of manufacturing an optical pickup device according to the present invention, the energy beam can be one type selected from the group consisting of a light beam, an X-ray, an electron beam, and an ion beam.

  As described above, according to the present invention, it is possible to provide a downsized optical pickup device by downsizing and / or integrating optical elements constituting the optical pickup device.

  Referring to FIG. 1, the optical pickup device according to the present invention is an optical pickup device capable of at least one of recording and reproducing information on an optical information recording medium 16, and a light source that emits a light beam; A plurality of optical elements for controlling the light beam are included. As these optical elements, for example, a polarizing beam splitter 13, a quarter wavelength plate 14, an objective lens 15, a focusing lens 17, and a light receiving element 18 are functionally arranged as shown in FIG. Thus, an optical pickup device capable of at least one of recording and reproducing information on the optical information recording medium 16 is obtained.

  That is, in the optical pickup device according to the present invention, the light beam from the light source 11 passes through the polarization beam splitter 13 and becomes the first linearly polarized light, and further becomes circularly polarized light by the quarter wavelength plate 14 and the objective lens 15. The return light condensed on the information recording surface 16a of the optical information recording medium 16 and reflected by the information recording surface 16a passes through the objective lens 15 and the quarter-wave plate 14 so that the first straight line The second linearly polarized light is linearly polarized in a direction rotated by 90 degrees with respect to the polarization direction of the polarized light, and the second linearly polarized light reflected by the polarization beam splitter 13 is converged by the converging lens 17 and is received by the light receiving element 18. Each optical element is arranged so as to be condensed.

  Here, in the optical pickup device according to the present invention, at least one of the optical elements includes a local region having a relatively high refractive index and a local region having a relatively low refractive index. DLC (Diamond Like Carbon) film. The present DLC film has a lower hardness (for example, Knoop hardness) than a conventional DLC film having a high hardness (for example, Knoop hardness of 2000 or more) and a high refractive index (for example, about 2.0) used for tools. Is less than 1000) and a low refractive index (for example, about 1.55). This DLC film can be formed on a silicon substrate, a glass substrate, and other various substrates by a plasma CVD (chemical vapor deposition) method.

  In the translucent DLC film according to the present invention, a local region having a relatively high refractive index and a local region having a relatively low refractive index are formed. By forming local regions having different refractive indexes in this way, light passing therethrough can be refracted and / or diffracted. In such a refractive index modulation type diffraction grating, a difference in film thickness in the relief type diffraction grating is not required, so that a more compact optical element can be designed.

  By irradiating the light transmissive DLC film of the present invention with an energy beam, the refractive index of the DLC film can be increased. As an energy beam for increasing the refractive index of the DLC film, an ion beam, an electron beam, X-rays, synchrotron radiation (SR) light, ultraviolet (UV) light, or the like can be used. Among these energy beam irradiations, it has been confirmed at present that the maximum refractive index change amount of the DLC film can be increased to about Δn = 0.65 by He ion beam irradiation. In addition, the maximum amount of change in the refractive index of the DLC film can be increased to about Δn = 0.50 at present under SR light irradiation. Furthermore, even with UV light irradiation, the maximum amount of change in the refractive index of the DLC film can be increased to about Δn = 0.20 at present. The amount of change in the refractive index of the DLC film due to energy beam irradiation is the amount of change in the refractive index of conventional glass due to ion exchange (at most Δn = 0.17) or the amount of refractive index change due to UV light irradiation of silica glass ( It can be seen that it is significantly larger than Δn = about 0.01 or less.

  Therefore, a local region having a relatively high refractive index and a local region having a relatively low refractive index can be formed by locally irradiating the translucent DLC film in the present invention with an energy beam. it can.

  In the optical pickup device according to the present invention, referring to FIG. 1, a collimator lens 19 can be further added as an optical element. Here, the collimator lens 19 refers to a lens for collimating (collimating) a light beam group in the optical pickup device. The position of the collimator lens 19 is not particularly limited. In FIG. 1, the collimator lens 19 is disposed between the quarter-wave plate 14 and the objective lens 15. For example, the collimator lens 19 is disposed between the light source 11 and the polarization beam splitter 13 (see FIG. (Not shown).

  At least one of the optical elements in the optical pickup device according to the present invention, for example, at least one of the polarization beam splitter 13, the quarter wavelength plate 14, the objective lens 15, the focusing lens 17 and the collimator lens 19, is formed by using the DLC film. By using and miniaturizing, the optical pickup device can be miniaturized.

  In the optical pickup device according to the present invention, the optical element including the DLC film can be at least one of a polarizing beam splitter and a quarter wavelength plate. Here, at least one of the polarization zoom splitter and the quarter wavelength plate can include a refractive index modulation type diffraction grating formed in the DLC film. Here, the refractive index modulation type diffraction grating formed in the DLC film is a local region having a relatively high refractive index (hereinafter referred to as a high refractive index region 2a) in the DLC film 2, as shown in FIG. And a diffraction grating in which local regions with relatively low refractive index (hereinafter referred to as low refractive index region 2b) are regularly formed.

  The above-described refractive index modulation type diffraction grating included in the optical pickup device according to the present invention is formed, for example, as follows with reference to FIG.

First, as shown in FIG. 3A, an SiO ₂ substrate having a refractive index of 1.44 and a main surface of 5 mm × 5 mm is used as the substrate 1, and the DLC film 2 is formed on the SiO ₂ substrate. Deposited to a thickness of 2 μm by plasma CVD. There is no particular limitation on the thickness of the DLC film forming the refractive index modulation type diffraction grating, and the thickness can be set to an arbitrary thickness. However, if the DLC film is too thick, it is not preferable because the light absorption effect by the film becomes too large. Further, if the DLC film is too thin, it tends to be difficult to obtain a sufficient diffraction effect, which is not preferable. Among the currently available DLC films, a DLC film having a thickness of preferably 0.5 to 10 μm is used for forming a refractive index modulation type diffraction grating. However, if a DLC film having a smaller light absorption coefficient is obtained, a thicker DLC film can be used, and if a change rate of refractive index can be increased, a thinner DLC film can be used.

Next, as shown in FIG. 3B, a gold mask 3b is formed on the DLC film 2 by a lift-off method. In this gold mask 3b, gold stripes having a width of 0.5 μm and a length of 5 mm were repeatedly arranged at intervals of 0.5 μm. That is, the gold mask 3b had a line and space pattern. After that, the He ion beam 4 was injected through the opening of the gold mask 3b at a dose of 5 × 10 ¹⁷ / cm ² in a direction perpendicular to the main surface 2h of the DLC film 2 under an acceleration voltage of 800 keV. .

  As a result, in the DLC film 2, a region where He ions are not implanted becomes a low refractive index region 2b having a refractive index of 1.55, and a region where He ions are implanted is a high refractive index having a refractive index of 2.05. It became rate area 2a. The refractive index difference in such a DLC film is much larger than the refractive index difference obtained in quartz glass, and it is possible to form a diffraction grating layer having a sufficiently large diffraction efficiency.

  Next, as shown in FIG. 3C, the gold mask 3b is removed by etching, and the high refractive index region 2a and the low refractive index region 2b are regularly formed in the DLC film 2. Are formed.

  2 shows a diffraction grating in which the interface 2s between the high refractive index region 2a and the low refractive index region 2b in the DLC film 2 and the main surface 2h of the DLC film 2 are orthogonal to each other. By injecting a He ion beam inclined with respect to the main surface of the film, the interface 2s between the high refractive index region 2a and the low refractive index region 2b in the DLC film 2 as shown in FIG. It is also possible to form a diffraction grating that is inclined with respect to the two principal surfaces 2h.

  Although not shown, a diffraction grating having a refractive index continuously changed near the interface between the high refractive index region and the low refractive index region by changing the thickness of the mask layer that shields the He ion beam. It is also possible to form.

(Polarized beam splitter)
A polarizing beam splitter including a refractive index modulation type diffraction grating will be described below. Referring to FIG. 5, this polarizing beam splitter is a line-and-space pattern formed by a high refractive index region and a low refractive index region. The high refractive index region has a width of 0.5 μm and a length of 5 mm. Are arranged at intervals of 0.5 μm, and the interface 2s between the high refractive index region 2a and the low refractive index region 2b is orthogonal to the main surface 2h of the DLC film 2.

  When beam light including S-polarized light and P-polarized light (corresponding to TM wave) is incident on the main surface 2h of the polarizing element, S-polarized light is transmitted as 0th-order diffracted light and P-polarized light is diffracted as -1st-order diffracted light. The That is, the beam light can be separated into two orthogonal linearly polarized light, P-polarized light and S-polarized light. The fact that the polarization can be separated by the diffraction grating is described in, for example, Applied Optics, Vol. 41, 2002, pp. 3558-3566.

(¼ wavelength plate)
A quarter-wave plate including a refractive index modulation type diffraction grating will be described. The quarter-wave plate has a structure similar to that of the polarizing beam splitter.

  The P-polarized light of the light beam having a wavelength of 0.66 μm and a beam diameter of 350 μm is converted into the 1/4 wavelength plate of this embodiment (at this time, the line and space of the high refractive index region on the main surface of the 1/4 wavelength plate). When the light is incident on a quarter wave plate so that the direction is rotated by 45 degrees with respect to the polarization direction of the P-polarized light, the light passing through the quarter wave plate is directed in the traveling direction and counterclockwise. Circularly polarized light rotating in the direction.

  Referring to FIG. 1, in the optical pickup device of the present invention, the composite that combines polarization beam splitter 13 and quarter-wave plate 14 operates as follows. That is, the light beam from the light source 11 is transmitted only by the first linearly polarized light (S-polarized light) by the polarization beam splitter 13 and rotated counterclockwise by the quarter wavelength plate 14 toward the light traveling direction. It becomes circularly polarized light and is condensed on the information recording surface 16 a of the optical information recording medium 16 through the collimator lens 19 and the objective lens 15. Next, the return light reflected by the information recording surface 16a (the direction of rotation of the circularly polarized light is reversed by reflection) passes through the objective lens 15 and the collimator lens 19 and turns the quarter-wave plate 14 in the reverse direction. Thus, the second linearly polarized light (P-polarized light) linearly polarized in the direction rotated by 90 degrees with respect to the polarization direction of the first linearly polarized light is obtained. Therefore, the light is diffracted by the polarization beam splitter 13 and can be condensed on the light receiving element 18 through the focusing lens 17.

Here, referring to FIG. 6, the composite of the polarizing beam splitter and the quarter-wave plate is a first functioning as a polarizing beam splitter on the first main surface of the substrate 1 formed of, for example, SiO ₂ . It is obtained by forming the DLC film 61 and forming the second DLC film 62 functioning as a quarter wavelength plate on the first main surface of the substrate 1.

  With respect to the polarizing beam splitter and the quarter-wave plate, diffraction in which the interface 2s between the high refractive index region 2a and the low refractive index region 2b is orthogonal to the main surface 2h of the DLC film 2 with reference to FIG. Although described using a grating, a diffraction grating in which the interface 2s between the high refractive index region 2a and the low refractive index region 2b is inclined with respect to the main surface 2h of the DLC film 2 as shown in FIG. Is possible.

  In the optical pickup device according to the present invention, the optical element including the DLC film can be at least one of an objective lens, a focusing lens, and a collimator lens. Here, at least one of the objective lens, the focusing lens, and the collimator lens can include either a refractive lens or a refractive index modulation type diffractive lens formed in the DLC film.

(Refractive lens)
The refractive lens formed in the DLC film included in the optical pickup device according to the present invention will be described. In the present refractive lens, referring to FIG. 7, a high refractive index region 2a is formed on one main surface 2h side of the DLC film 2, and the interface 2s between the high refractive index region 2a and the low refractive index region 2b is low. The refractive index region 2b has a curved surface protruding in a convex shape. The high refractive index region 2a including such a convex curved surface functions as a lens.

  The refractive lens is manufactured as follows with reference to FIG. First, as shown in FIG. 8A, a mask layer 3 is formed on the DLC film 2. As the mask layer 3, various materials having a function capable of limiting the transmission of the energy beam 4 can be used, but gold can be preferably used. The mask layer 3 has minute recesses 3a arranged in an array. Each of the recesses 3a has a bottom surface formed of a part of a substantially spherical surface or a part of a substantially cylindrical surface. The energy beam 4 is irradiated to the DLC film 2 through the mask layer 3 including the array of the recesses 3a.

  Next, as shown in FIG. 8B, the mask layer 3 is removed after the irradiation with the energy beam 4, thereby obtaining an array of lenses 2a formed in the DLC film 2. That is, an array of high refractive index regions 2 a is formed in the DLC film 2 corresponding to the array of recesses 3 a of the mask layer 3 by irradiation with the energy beam 4. At this time, since the recess 3a of the mask layer 3 has a spherical or cylindrical bottom surface, the thickness of the mask layer 3 increases from the center of the recess 3a toward the periphery. That is, the energy beam 4 is more easily transmitted in the central portion than in the peripheral portion of the concave portion 3a. Therefore, the high refractive index region 2a has a shape of a spherical convex lens or a cylindrical convex lens that is deep at the center and shallow at the periphery. As a result, each of these high refractive index regions 2a can act as one lens as it is.

  When the lens array is manufactured by the energy beam 4 as shown in FIG. 8, the thickness of the lens 2a is adjusted by adjusting the depth of the concave portion 3a having a substantially spherical shape or a substantially cylindrical surface shape. That is, its focal length can be adjusted. Further, the focal length of the lens 2a can be adjusted by changing the transmission ability of the irradiated energy beam 4 without changing the depth of the recess 3a. For example, when a He ion beam is used as the energy beam 4, the focal distance of the lens 2a can be shortened by increasing the acceleration energy of the ions and increasing the transmission power. Further, since the refractive index change Δn increases as the dose amount of the energy beam 4 with respect to the DLC film increases, the focal length of the lens 2a can also be adjusted by adjusting the dose amount.

  The mask layer 3 including the concave portion 3a having a substantially spherical or substantially cylindrical bottom as shown in FIG. 8A can be manufactured by various methods. For example, a mask layer 3 having a uniform thickness is formed on the DLC film 2, and a resist layer having minute holes arranged in an array or linear openings arranged in parallel is formed thereon. Then, by performing isotropic etching from a minute hole or a linear opening in the resist layer, a substantially hemispherical or substantially semi-cylindrical recess 3a is formed in the mask layer 3 below the minute hole. be able to.

  Further, the mask layer 3 including the concave portion 3a having a substantially spherical or substantially cylindrical bottom as shown in FIG. 8A is illustrated in the schematic cross-sectional view of FIG. It can also be produced simply using a stamping die that can be produced by the method.

  First, as shown in FIG. 9A, a resist pattern 92 is formed on a silica substrate 91, for example. The resist pattern 92 is formed on a plurality of minute circular regions arranged in an array on the silica substrate 91 or on a plurality of thin strip regions arranged in parallel.

  Next, as shown in FIG. 9B, the resist pattern 92 is heated and melted, and the resist 92a melted on each microcircular region or thin strip region has a substantially spherical shape or a substantially cylindrical surface depending on its surface tension. A convex lens shape.

  Next, as shown in FIG. 9C, if the silica substrate 91a is subjected to RIE (Reactive Ion Etching) together with the substantially convex lens-shaped resist 92b, the silica substrate 91a is etched while the diameter or width of the resist 92b is reduced by RIE. Is done.

  As a result, as shown in FIG. 9D, a silica stamping die 91c in which convex portions 91b having a substantially spherical shape or a substantially cylindrical surface shape are arranged is finally obtained. The height of the convex portion 91b can be adjusted by adjusting the ratio between the etching rate of the resist 92b and the etching rate of the silica substrate 91a in FIG.

  The stamping die 91c thus obtained can be preferably used for manufacturing the mask layer 3 including the recess 3a as shown in FIG. That is, for example, when the mask layer 3 is formed of a gold material, since gold is rich in spreadability, the concave portion 3a can be easily formed by imprinting the gold mask layer 3 with the stamping die 91c. it can. Further, since the stamping die 91c can be repeatedly used once it is manufactured, the recess 3a can be formed much more easily and at a lower cost than when the recess 3a in the mask layer 3 is formed by etching. .

  In addition, a refractive lens using a DLC film as in the present invention can form a lens having a high refractive index by irradiation with an energy beam, as compared with the case of using a conventional glass substrate. A refractive lens can be formed in a much thinner DLC film. However, even a refractive lens using a DLC film requires a thicker DLC film than a refractive index modulation type diffractive lens described below, and requires a thickness of about 10 μm to 20 μm or more.

(Refractive index modulation type diffractive lens)
Next, the refractive index modulation type diffractive lens formed in the DLC film included in the optical pickup device according to the present invention will be described. Referring to FIG. 10, the diffractive lens 100 is manufactured using the DLC film 2 and includes a plurality of concentric belt-shaped ring regions Rmn. Here, the symbol Rmn represents the nth band-shaped ring region in the mth ring zone, and also represents the radius from the center of the concentric circle to the outer periphery of the band-shaped ring region. The band-shaped ring regions Rmn have a reduced width as they are farther from the center of the concentric circles.

  The diffractive lens can be made thinner than the refractive lens, and the diffractive lens can be made in a DLC thin film having a thickness of about 1 to 2 μm. Therefore, by using this diffractive lens for at least one of the objective lens, the focusing lens, and the collimator lens of the optical pickup device, the optical pickup device can be easily downsized.

  Here, the adjacent band-shaped ring regions Rmn have different refractive indexes. When the diffractive microlens of FIG. 10 is a two-level diffractive lens, the ring zone including the band-like ring region up to n = 2 is included up to m = 3. In the same ring zone, the inner ring-shaped ring region has a higher refractive index than the outer ring zone.

  As can be inferred from this, in a four-level diffractive lens, one ring zone includes a band-shaped ring region up to n = 4th, and in this case as well, in the center of the concentric circle in the same ring zone. The closer the band-shaped ring region, the higher the refractive index. That is, four steps of refractive index change are formed from the inner peripheral side to the outer peripheral side in one ring zone. Then, such a four-stage refractive index change cycle is repeated m times for each ring zone.

  The outer peripheral radius of the band-shaped ring region Rmn can be set according to the following equation (1) from diffraction theory including scalar approximation. In this equation (1), L represents the diffraction level of the lens, λ represents the wavelength of light, and f represents the focal length of the lens. Further, the maximum refractive index change amount Δn must be capable of producing the maximum phase modulation amplitude Δφ = 2π (L−1) / L.

  The two-level diffractive lens as shown in FIG. 10 is manufactured as follows with reference to FIG.

  First, as shown in FIG. 11A, a Ni conductive layer 5, for example, is formed on the DLC film 2 by a well-known EB (electron beam) deposition method. On this Ni conductive layer 5, a resist pattern 6 is formed so as to cover the band-shaped ring region Rmn (m = 1 to 3) corresponding to n = 1 in FIG. A gold mask 3b is formed in the opening of the resist pattern 6 by electroplating.

  Next, as shown in FIG. 11B, the resist pattern 6 is removed, leaving the gold mask 3b. Then, the DLC film 2 is irradiated with the energy beam 4 through the opening of the gold mask 3b. As a result, the refractive index of the band-shaped ring region Rm1 irradiated to the energy beam 4 is increased to form a high refractive index region 2a, and the band-shaped ring region Rm2 masked with the energy beam 4 has the refractive index of the original DLC film. The low refractive index region 2b is maintained. That is, a two-level diffractive lens as shown in FIGS. 10 and 11 is obtained.

  In the example of FIG. 11, a mask layer is formed on each DLC film, but it goes without saying that the DLC film may be irradiated with an energy beam using a separately produced independent mask. In addition, it will be understood that a multi-level diffractive lens can be formed by repeatedly irradiating the DLC film with an energy beam using a mask with sequentially adjusted patterns.

  Furthermore, instead of the stamping die as shown in FIG. 9 (d), a gold mask layer on the DLC film using a stamping die including a concentric belt-shaped ring region whose thickness is changed in multiple steps. It is also possible to fabricate a multi-level diffractive lens by one-time energy beam irradiation by engraving an energy beam through the engraved gold mask layer.

  Furthermore, although the diffractive lens corresponding to the spherical convex lens of the refractive lens has been described above, the present invention can be similarly applied to the diffractive lens corresponding to the columnar convex lens of the refractive lens. Will be understood. In that case, instead of the plurality of concentric strip-shaped ring regions whose refractive indexes are modulated, a plurality of parallel strip-shaped regions whose refractive indexes are modulated may be formed. In this case, for example, in the cross-sectional view of FIG. 10B, the plurality of parallel band-shaped regions whose refractive indexes are modulated extend vertically to the paper surface of the figure. In that case, the gold mask 3b in FIG. 11 (b) only needs to extend perpendicularly to the plane of the drawing.

  As described above, at least one of the optical elements constituting the optical pickup device includes a translucent DLC film including a relatively high refractive index local region and a relatively low refractive index local region. More specifically, at least one of the optical elements includes any one of a refractive index modulation type diffraction grating, a refractive type lens, and a refractive index modulation type diffraction lens formed in the DLC film. The optical element can be downsized, and the optical pickup device can be downsized. Further, the optical pickup device can be further downsized by stacking and arranging these optical elements.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  As described above, the present invention can be widely used for an optical pickup device capable of at least one of recording and reproducing information on an optical information recording medium.

It is a schematic structure schematic diagram of an optical pickup device. 1 is a cross-sectional view schematically illustrating one refractive index modulation type diffraction grating formed in a DLC film according to the present invention. FIG. 3 is a cross-sectional view schematically illustrating a method of forming the refractive index modulation type diffraction grating of FIG. 2. It is sectional drawing which illustrates typically another refractive index modulation type diffraction grating formed in the DLC film in this invention. It is sectional drawing which illustrates typically the polarizing beam splitter in this invention. FIG. 3 is a three-dimensional view schematically illustrating a complex of a polarizing beam splitter and a quarter wavelength plate in the present invention. It is sectional drawing which illustrates typically the refractive lens in this invention. It is sectional drawing which illustrates typically the manufacturing method of the refractive lens of FIG. It is sectional drawing which illustrates typically the formation method of the stamp type | mold which can be utilized for the manufacturing method of the refractive lens of FIG. It is a figure which illustrates typically the refractive index modulation type diffraction lens in the present invention. Here, (a) is a schematic plan view of the diffractive lens, and (b) is a schematic cross-sectional view of the diffractive lens. It is sectional drawing which illustrates typically the preparation methods of the diffraction lens of FIG. It is sectional drawing which illustrates typically the relief type lens in the conventional optical pick-up apparatus.

Explanation of symbols

  1 substrate, 2 DLC film, 2a high refractive index region, 2b low refractive index region, 2h main surface, 2s interface, 3 mask layer, 3a recess, 3b gold mask, 4 energy beam, 5 conductive layer, 6,92 resist pattern , 11 Light source, 13 Polarizing beam splitter, 14 1/4 wavelength plate, 15 Objective lens, 16 Optical information recording medium, 16a Information recording surface, 17 Focusing lens, 18 Light receiving element, 19 Collimator lens, 61 First DLC film, 62 Second DLC film, 91 silica substrate, 91a silica substrate being etched, 91b convex portion, 91c imprint mold, 92 resist pattern, 92a molten resist, 92b resist being etched, 100 diffraction lens, 1200 next time Folding light, 121 first-order diffracted light, 122 second-order diffracted light.

Claims (8)

An optical pickup device capable of at least one of recording and reproduction of information on an optical information recording medium,
A light source that emits a light beam, and a plurality of optical elements that control the light beam,
At least one of the optical elements includes an optical pickup device including a translucent DLC film including a local region having a relatively high refractive index and a local region having a relatively low refractive index.   The optical pickup device according to claim 1, wherein the optical element including the DLC film is a polarization beam splitter.   The optical pickup device according to claim 1, wherein the optical element including the DLC film is a ¼ wavelength plate.   The optical pickup device according to claim 1, wherein the optical element including the DLC film is an objective lens.   The optical pickup device according to claim 1, wherein the optical element including the DLC film is a focusing lens.   The optical pickup device according to claim 1, wherein the optical element including the DLC film is a collimator lens.   The method for manufacturing the optical pickup device according to claim 1, wherein the relatively high refractive index region in the DLC film is formed by irradiation with an energy beam.   The method of manufacturing an optical pickup device according to claim 7, wherein the energy beam is one selected from the group consisting of a light beam, an X-ray, an electron beam, and an ion beam.

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