JP2005310352A - Solid immersion lens, condenser lens, optical pickup, optical recording and reproducing device, and method for forming solid immersion lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid immersion lens which is easy to hold a lens and assemble and excellent in workability, to provide the solid immersion lens and condenser lens suitable for near field optical recording and reproduction, and to provide an optical pickup and an optical recording and reproducing device dealing with high recording density and a large capacity by using this. <P>SOLUTION: A holding part 2 having a straight line in the shape of a cross section along an optical axis is provided in at least a part of the ineffective area of incident light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid immersion lens (Solid Immersion Lens), a condensing lens using the same, an optical pickup device and an optical (or magneto-optical) recording / reproducing device, and a method for forming a solid immersion lens. Specifically, a solid immersion suitable for a so-called near-field optical recording / reproducing system that performs recording / reproducing on an optical (or magneto-optical) recording medium by using a material having a high refractive index of the optical lens and increasing the numerical aperture of the condenser lens. The present invention relates to a lens, a condenser lens, an optical pickup device, an optical recording / reproducing device, and a method for forming a solid immersion lens.

Optical recording media (including magneto-optical recording media) represented by CD (Compact Disc), MD (Mini Disc), and DVD (Digital Versatile Disc) are widely used as storage media for music information, video information, data, programs, and the like. It's being used. However, for higher sound quality, higher image quality, longer time, and larger capacity of music information, video information, data, programs, etc., a larger capacity optical recording medium and optical recording / reproducing for recording / reproducing the same An apparatus (including a magneto-optical recording / reproducing apparatus) is desired.
Therefore, in order to cope with these, in the optical recording / reproducing apparatus, the wavelength of the light source, for example, the semiconductor laser is shortened, the numerical aperture of the condensing lens is increased, and the light spot converged through the condensing lens is reduced. The diameter has been reduced.

  For example, with regard to semiconductor lasers, GaN semiconductor lasers whose oscillation wavelength has been shortened from the 635 nm to 400 nm bands of conventional red lasers have been put into practical use, and thereby the diameter of the light spot is being reduced. Further, for example, for further shortening of the wavelength, a far ultraviolet solid-state laser UW-1010 manufactured by Sony Corporation that continuously oscillates light having a single wavelength of 266 nm has been put on the market. It is being planned. In addition to this, research and development of a Nd: YAG laser double wave laser (266 nm band), a diamond laser (235 nm band), a GaN laser double wave laser (202 nm band), and the like are underway.

  Further, by using an optical lens having a large numerical aperture represented by a solid immersion lens (SIL), for example, a condensing lens having a numerical aperture of 1 or more is realized, and the objective surface of the condensing lens is used as an optical recording medium. Then, a so-called near-field optical recording / reproducing system in which recording / reproducing is performed by bringing the light source wavelength close to about one-tenth of the light source wavelength has been studied (for example, see Patent Document 1).

  In this near-field optical recording / reproducing system, it is important to maintain the distance between the optical recording medium and the condenser lens in an optical contact state with high accuracy. In addition, the diameter of the light beam emitted from the light source and incident on the condensing lens becomes small, and the distance between the optical recording medium and the condensing lens is very small, about tens of nm or less. The tilt margin with the lens, the so-called tilt margin, becomes very small, and the condensing lens is greatly restricted in shape.

  FIG. 31 shows a schematic configuration diagram of an example of a solid immersion lens. The solid immersion lens 11 and the optical lens 12 can be arranged in order from the objective side such as the optical recording medium 30 to constitute a near-field condensing lens. The solid immersion lens 11 is formed in a hemisphere or a super hemisphere (a super hemisphere in the illustrated example), and the thickness along the optical axis c is r if the thickness is hemispherical, as shown in FIG. In the case of the shape, r (1 + 1 / n) is configured. In FIG. 31, in order to facilitate understanding of the shape of the solid immersion lens, a side view and a plan view viewed from the objective side are shown side by side.

  When the condensing lens having such a configuration is applied to an optical recording / reproducing apparatus, for example, it is mounted on an optical pickup apparatus having a biaxial actuator, and the distance between the optical recording medium and the condensing lens is maintained in an optical contact state. To do. When used for magneto-optical recording, a magnetic head device used for magnetic recording / reproducing is incorporated in the optical pickup device, and the distance between the optical recording medium and the condenser lens is similarly maintained in an optical contact state. It is said.

  Other solid immersion lens shapes include a hemispherical or super hemispherical objective surface that has been processed into a conical shape, and a magnetic coil that surrounds the central portion of the objective surface. (For example, refer to Patent Document 2).

Japanese Laid-Open Patent Publication No. 5-189796 JP 2003-161801 A

  As described above, in the near-field optical recording / reproducing method, the condensing lens generally achieves a numerical aperture of 1 or more by combining two optical lenses, a solid immersion lens and an optical lens, which are arranged in order from the object side. However, as the assembly accuracy of these lenses increases, the higher the numerical aperture, the higher the accuracy required for the distance between the lenses and their relative angles, and it is also necessary to maintain this accuracy against environmental changes. It is done.

In addition, the size of each lens in the optical system including the solid immersion lens reduces the weight burden of the biaxial actuator on which it is mounted, and improves the servo characteristics such as focusing characteristics, tracking characteristics, and seek time. Therefore, a reduction in diameter is required. In order to realize a small and lightweight lens, it is necessary to make the thickness of the solid immersion lens as thin as possible, that is, to make the radius of curvature r as small as possible or the refractive index n of the lens material as large as possible. .
Low-cost materials that achieve a high refractive index are currently relatively limited. For example, when glass (SiO ₂ ) is used as the lens material, the refractive index is limited to about 1.5, so In order to reduce the size, it is required to reduce the thickness of the solid immersion lens, that is, to reduce the curvature radius of the lens.

In addition, as shown in FIG. 31, a general solid immersion lens used in the condensing lens, the optical pickup device, and the optical recording / reproducing device having the above-described configuration has a planar structure in which the objective surface 6 is flat. .
Therefore, the margin with respect to the tilt with the optical recording medium is almost zero, and when the lens or the optical recording medium is tilted for some reason, the lens and the optical recording optical medium come into contact with each other. In order to realize the above-mentioned near-field optical recording / reproducing method, the condensing lens including the solid immersion lens must be precisely spaced and relative angled. High assembly accuracy is required to control, bond and hold.

  However, when the curvature radius of the solid immersion lens is extremely small, for example, a radius of curvature of 1.0 mm or less, the condenser lens is assembled and formed with sufficient assembly accuracy to realize the above-mentioned near-field optical recording / reproduction. However, it is difficult to configure an optical pickup device and an optical recording / reproducing device that can maintain an optical contact state.

  In view of the above-described problems, the present invention provides a solid immersion lens that is easy to hold and assemble the lens and has excellent processability, and provides a solid immersion lens and a condensing lens suitable for near-field optical recording and reproduction. In addition, an object of the present invention is to provide an optical pickup device and an optical recording / reproducing device that can be used with a high recording density and a large capacity.

  In order to solve the above-described problem, the solid immersion lens according to the present invention is provided with a holding portion having a straight line in a cross-sectional shape along the optical axis in at least a part of an invalid region of incident light, that is, a region where incident light does not pass. It is characterized by being made.

The solid immersion lens according to the present invention is characterized in that, in the above-described configuration, a convex portion is formed on the objective side of the holding portion.
Furthermore, the solid immersion lens according to the present invention is characterized in that, in the above-described configuration, the convex portion is configured as a cylindrical shape projecting toward the objective side, a cylindrical shape having an elliptical cross section, or a prism shape.

The solid immersion lens according to the present invention is characterized in that, in the above-described configuration, the convex portion is configured as a conical shape from the holding portion toward the object side, a conical shape having an elliptical cross section, or a pyramid shape.
Furthermore, the solid immersion lens according to the present invention is characterized in that, in the above-described configuration, the convex portion is configured as a curved surface or a spherical surface protruding from the holding portion toward the object side.
The solid immersion lens according to the present invention is characterized in that, in each of the above-described configurations, a holding processing portion is formed on at least a part of the side surface of the holding portion.

  In addition, the condenser lens according to the present invention includes a solid immersion lens according to the above-described configuration of the present invention, and an optical lens that is arranged on the opposite side of the objective side so that the optical axis of the solid immersion lens coincides with the optical axis. Features.

Furthermore, an optical pickup device according to the present invention includes a solid immersion lens lens according to the above-described configuration of the present invention, an optical lens arranged on the side opposite to the objective side with the solid immersion lens aligned with the optical axis, and a light source. The light spot is formed by converging the light emitted from the light source by a condensing lens including at least a solid immersion lens and an optical lens.
An optical recording / reproducing apparatus according to the present invention includes an optical pickup device including a condensing lens using the solid immersion lens according to the above-described configuration of the present invention, and the condensing lens is used for the focusing direction and / or tracking of the optical recording medium. It is characterized by providing a control driving means for controlling and driving in the direction.

  Furthermore, the solid immersion lens forming method according to the present invention is a solid immersion lens forming method in which a lens material body is processed into a cylindrical shape, and a spherical portion having a radius of curvature r is formed in a part of the lens material body. And at least a step of performing.

  As described above, the solid immersion lens according to the present invention has a solid immersion on the side surface of the holding portion by providing a holding portion having a straight line in a cross-sectional shape along the optical axis in at least a part of the invalid region of incident light. Fixing by adhesion with a holding body for holding a lens can be performed more robustly than in the past, and more stable holding is possible. Accordingly, it is possible to stably hold a solid immersion lens having a small curvature radius, which is a limit of the conventional solid immersion lens, and to configure the solid immersion lens with sufficient assembly accuracy.

  Further, the solid immersion lens according to the present invention is configured by forming a convex portion on the objective side of the holding portion in the above-described configuration, so that the solid immersion of the conventional configuration in which the objective surface is entirely planar is formed. Compared with a lens, since the area of the object surface is narrow, the tilt margin with respect to an object such as an optical recording medium can be increased as compared with the conventional case, and the stability of recording and reproduction with respect to the optical recording medium can be improved. It becomes possible to raise.

Furthermore, the solid immersion lens according to the present invention is configured so that the convex portion has a cylindrical shape protruding toward the objective side, a cylindrical shape having an elliptical cross section, or a prismatic shape, thereby reliably reducing the area of the objective surface, The tilt margin with respect to the optical recording medium or the like can be reliably improved.
In addition, the solid immersion lens according to the present invention is configured such that the convex portion is configured as a conical shape from the holding portion toward the objective side, a conical shape having an elliptical cross section, or a pyramid shape, thereby reliably reducing the area of the objective surface. The inclination margin can be increased, and the manufacture can be easily performed by mechanical processing or the like.

Furthermore, the solid immersion lens according to the present invention is configured such that the convex portion is formed as a curved surface or a spherical shape protruding from the holding portion toward the object side, and similarly, the area of the object surface is reduced to improve the tilt margin. And the manufacture thereof can be facilitated.
In the solid immersion lens according to the present invention, in each of the above-described configurations, since the holding processing portion is formed on at least a part of the side surface of the holding portion, for example, a concave portion is provided as the holding processing portion or the surface is roughened. By performing the treatment, it is possible to more firmly and stably fix the holding body.

Further, according to the condensing lens using the solid immersion lens of the configuration of the present invention, since the solid immersion lens can be held more firmly and stably, the assembly accuracy with the optical lens can be improved. Thus, it is possible to easily assemble a condenser lens having a large numerical aperture as compared with the conventional one.
Further, by providing a convex portion on the objective side of the solid immersion lens, the tilt margin with respect to the optical recording medium or the like can be increased as compared with the conventional case, and therefore the assembly accuracy can be further improved.

Furthermore, in the optical pickup device and the optical recording / reproducing device configured using this condenser lens, the solid immersion lens can be held firmly and stably, and the inclination between the solid immersion lens and the optical recording medium, etc. Since the margin can be increased, the assembly accuracy margin can be increased as compared with the conventional case.
Since the diameter of the solid immersion lens can be reduced, the optical pickup device and the optical recording / reproducing device configured using the condenser lens are controlled and driven in the focusing direction or the tracking direction of the optical recording medium. As a result, it is possible to achieve stable control of the condenser lens, and to improve servo characteristics such as focusing servo, tracking servo, and seek time.

Further, according to the method for forming a solid immersion lens according to the present invention, when forming the holding portion in the solid immersion lens, a step of processing the lens material body into a cylindrical shape, and a part of the lens material body with a curvature radius r. By the step of forming the spherical portion, it is possible to easily and reliably form a solid immersion lens that can be firmly and stably held by the holding body.
Furthermore, in the method for forming a solid immersion lens according to the present invention, in addition to the above-described steps, by forming a convex portion on the objective side of the lens material body, the holding with the holding body is robust and stable. It is possible to easily and reliably form a solid immersion lens capable of increasing the tilt margin with respect to an optical recording medium or the like as compared with the conventional case.

Hereinafter, an example of the best mode for carrying out the present invention will be described with reference to the drawings.
The present invention relates to a solid immersion lens and a method of forming the same, a condensing lens composed of the solid immersion lens and an optical lens arranged on the side opposite to the objective side, and the condensing lens. And an optical pickup apparatus employing a so-called near-field optical recording / reproducing system, and an optical recording / reproducing apparatus having the optical pickup apparatus.

  First, prior to the description of the solid immersion lens and the method for forming the same according to the present invention, examples of embodiments applied to the condenser lens, the optical pickup device, and the optical recording / reproducing device will be described with reference to FIGS. To do. 1 to 5, the shape of the solid immersion lens is shown by simplifying an example according to the configuration of the present invention in order to easily explain the arrangement configuration thereof. It goes without saying that various shapes of the configuration of the present invention can be adopted.

FIG. 1 is a schematic configuration diagram showing an example of a condensing lens using a solid immersion lens according to the present invention. A solid immersion lens 11 and an optical lens 12 according to the configuration of the present invention are arranged with their optical axes aligned in this order with respect to, for example, an optical recording medium 30 of a lens object. The solid immersion lens 11 is hemispherical or super hemispherical with a radius of curvature r, and the thickness along the optical axis is r if hemispherical, and if the refractive index is n in the case of super hemispherical, r (1 + 1 / n). The example in FIG. 1 shows an example in which the spherical portion is a super hemisphere. With such a configuration, it is possible to provide a condensing lens 13 having a high numerical aperture exceeding the numerical aperture NA of the optical lens 12.
Actually, the solid immersion lens 11 and the optical recording medium 30 are not in contact with each other, but the distance between the solid immersion lens 11 and the optical recording medium 30 is sufficiently smaller than the thickness of the solid immersion lens 11. Therefore, the interval is not shown in FIGS.

  FIG. 2 is a schematic configuration diagram showing an example of the configuration of the optical system of the optical pickup device using the solid immersion lens and the condenser lens shown in FIG. For example, first and second beam splitters 14 and 15 are arranged between a light source and a photodetector (not shown) and a condenser lens 13 including a solid immersion lens 11 and an optical lens 12. If the optical recording medium 30 is, for example, in the form of a disk, it is mounted on a spindle motor (not shown) and rotated at a predetermined rotational speed.

The optical pickup device shown in FIGS. 1 and 2 is provided with means for controlling and driving the condenser lens 13 in the tracking direction and the focusing direction.
Examples of this means include a biaxial actuator used for a general optical pickup and a slider used for a magnetic head device.
The form of the control drive means of these condensing lenses 13 is shown below.

FIG. 3 is a schematic configuration diagram of an example of an optical pickup device using a biaxial actuator as a control driving unit. As shown in FIG. 3, the condenser lens 13 is fixed by a holding body 20 so that the optical axes of the solid immersion lens 11 and the optical lens 12 coincide with each other, and the holding body 20 is controlled in the focusing direction and / or the tracking direction. It is fixed to a driven biaxial actuator 16.
As shown in FIG. 3, the biaxial actuator 16 includes a tracking coil 17 for controlling and driving the condenser lens 13 in the tracking direction, and a focusing coil 17 for controlling and driving the focusing lens 13 in the focusing direction.

The distance between the optical recording medium 30 and the solid immersion lens 11 can be controlled by the biaxial actuator 16 by, for example, monitoring the amount of return light and feeding back the distance information, so that the solid immersion lens 11 and the optical recording medium 30 can be controlled. The distance between the solid immersion lens 11 and the optical recording medium 30 is controlled so as to avoid a collision.
Further, in this biaxial actuator 16, it is possible to move the focused spot to a desired recording track by monitoring the amount of light returning in the tracking direction and feeding back the position information.

Next, FIG. 4 shows a schematic configuration diagram in the case where a slider is employed as the control driving means of the condenser lens 13 shown in FIGS.
As shown in FIG. 4, the condensing lens 13 can be fixed to a slider 21 that is controlled and driven in the tracking direction. The slider 21 is, for example, a movable optical unit (not shown) that moves in the tracking direction via an elastic body such as a gimbal 22 having elasticity only in the surface-contact direction of the optical recording medium 30 or another elastic body not shown. ) Is supported. The converging lens 13 can be opposed to a predetermined track by driving the movable optical unit in the tracking direction by a control driving unit constituted by a linear motor or the like.
A gas flow generated with the rotation of the optical recording medium 30 flows between the optical recording medium 30 and the slider 21, and a gas thin film is formed that balances the pressing force of the elastic body toward the optical recording medium 30. 21 is configured to float with respect to the optical recording medium 30 while maintaining a certain distance, for example, a distance of 50 nm. That is, when the optical recording medium 30 is rotated at a predetermined number of revolutions and information is reproduced from the optical recording medium 30 or information is recorded on the optical recording medium 30, the solid immersion lens 11 constituting the condenser lens 13. And the optical recording medium 30 can be kept at a substantially constant distance by the slider 32.

  Hereinafter, a schematic configuration of the optical pickup device will be described with reference to FIG. 2 again. Outgoing light emitted from a light source, for example, a semiconductor laser, is converted into parallel light by a collimator lens (not shown) (L1), passes through the first beam splitter 14 (L), and passes through the condenser lens 13. The light is condensed on the information recording surface of the recording medium 30. The return light reflected by the information recording surface passes through the condenser lens 13, is reflected by the first beam splitter 14 (L 2), and enters the second beam splitter 15. The return light beams (L3 and L4) separated by the second beam splitter 15 are condensed on a focusing photodetector and a signal photodetector (not shown), and a focusing error signal and a reproduced pit signal are collected. Etc. are detected.

  The return light reflected by the second beam splitter is also collected on the tracking photodetector, and a tracking error signal is detected. If necessary, this optical pickup device includes a biaxial actuator for fixing the condenser lens 13 or a remaining focus error component followed by the slider and a condenser lens for surface vibration of the optical recording medium 30. A relay lens that can correct the error component generated during the assembly process by changing the interval between the two lenses may be inserted between the first beam splitter 14 and the optical lens 12.

  When the solid immersion lens 11 and the optical lens 12 are fixed to the slider 21, the condenser lens is used as a means for correcting the remaining focus error component followed by the slider 21 and the error component generated during the condenser lens assembly process. 13 may be fixed to the slider 21, and the optical lens 12 may be configured to be movable in the optical axis direction by a piezoelectric element or the like.

  Further, in the case of an optical recording / reproducing apparatus in which the spindle motor has means for mounting a plurality of optical recording media, the slider 21 is provided with a mirror 23 that bends the optical axis approximately 90 degrees as shown in the schematic configuration diagram of FIG. Is preferred. In the optical recording / reproducing apparatus having such a configuration, the interval between the optical recording media can be reduced, and as a result, the apparatus can be reduced in size and thickness.

  The above-described optical pickup device includes a reproduction-only unit that performs only reproduction, a recording-only unit that performs only recording, and a recording / reproducing unit that can perform both recording and reproduction. In addition, each of the optical pickup devices described above can be configured to include a device in which a magnetic coil or the like is incorporated in a part of the optical pickup device by combining the magneto-optical recording method and the near-field light reproducing method. The optical recording / reproducing apparatus includes a reproduction-only apparatus that performs only reproduction, a recording-only apparatus that performs only recording, and a recording / reproduction apparatus that can perform both recording and reproduction.

Next, each example of the shape of the solid immersion lens according to the present invention will be described.
[1] First Embodiment As described above, the solid immersion lens according to the present invention has an invalid region of incident light, that is, an incident light as shown in FIG. The holding portion 2 having a straight line in a cross-sectional shape along the optical axis c is provided in at least a part of the region where light does not pass.
In the illustrated example, an example of a solid immersion lens 11 provided with a super hemispherical spherical portion 1 having a radius of curvature of r, a refractive index of n, and a thickness in the direction along the optical axis of r (1 + 1 / n) is provided. Indicates. In this case, the optical axis is approximately centered from the position where the radius of the section perpendicular to the optical axis indicated by the one-dot chain line c of the spherical portion 1 is substantially r, that is, from the position indicated by the broken line R to the ineffective region of incident light on the objective side. An example in which the holding portion 2 having a linear portion substantially parallel to the optical axis c is provided as a cylindrical shape as an axis. In FIG. 6, in order to facilitate understanding of the shape of the solid immersion lens, a side view and a plan view viewed from the objective side are shown side by side.
In this example, the case where the radius from the optical axis c of the cylindrical holding part 2 is set to about r is shown.
In the example shown in the figure, the spherical portion 1 is shown as a super hemisphere. However, the spherical portion 1 may be hemispherical, and in this case, the thickness along the optical axis is set as r.

  In the near-field optical recording / reproducing system for the magneto-optical recording medium, a magnetic field is required at the time of recording and / or reproduction. Therefore, a magnetic coil or the like is attached to a part of the objective surface of the solid immersion lens 11. May be.

The solid immersion lens 11 is made of a material having a large refractive index with respect to the wavelength of incident light, a large transmittance, and a small light absorption, such as a laser light source equipped in the optical recording / reproducing apparatus used. Is preferred. For example, S-LAH79 manufactured by OHARA INC., Which is a high refractive index glass, Bi ₄ Ge ₃ O ₁₂ , SrTiO ₃ , ZrO ₂ , HfO ₂ , SiC, diamond, which are high refractive index ceramics, and a high refractive index single crystal material. Etc. are suitable.

  These lens materials desirably have an amorphous structure or a cubic structure in the case of a single crystal. When the optical lens material has an amorphous structure or a cubic structure, it is not necessary to align the orientation with high accuracy, and a conventional ball polishing method or polishing apparatus can be used. Further, there is an advantage that an etching process and a polishing process for manufacturing an optical lens can be easily applied without worrying about the orientation of the material.

As described above, in the present invention, since the cylindrical holding portion 2 is provided on at least a part of the objective side, the holding body in the holding portion 2 is different from the conventional example described in FIG. Bonding and fixing with can be performed robustly and stably.
That is, as shown in FIG. 31, in the case of a conventional solid immersion lens in which the side surface shape is a spherical shape following the objective surface from the spherical portion, the side surface shape is a spherical shape. In the case of holding by a holding body such as, a process such as processing the inner surface of the lens holder side into a spherical shape is required, and the bonding method and holding method become difficult, and there is a problem that it is difficult to fix firmly and stably. .
In particular, when a solid immersion lens having a small diameter of about 0.5 mm or less is held with the lens holder, it is difficult to bond and hold the spherical shape portion of the lens side surface because the bonding area with the lens holder becomes very small. It becomes very difficult to fix sufficiently and stably.

  On the other hand, in the case of the configuration of the present invention, as shown in FIG. 6, in the holding part 2, the cross section has a straight part, and a force can be applied evenly. With a simple configuration, it is possible to easily and firmly adhere and fix to this holding portion, and even a solid immersion lens with a small diameter that has been difficult to hold firmly can be held sufficiently stably. .

  In the illustrated example, a case is shown in which the holding unit 2 is provided from the position where the radius of the cross section indicated by the broken line R is approximately r to the objective surface 6, but the holding unit 2 is at least one of the invalid regions of incident light. If it is provided in the portion, the holding portion can be used to make the holding stronger and more stable than in the past.

As described above, according to the present invention, since it is possible to use a solid immersion lens having a smaller diameter than in the past, the weight of the entire condensing lens in combination with a small solid immersion lens and an optical lens is possible. Can be reduced.
Therefore, in the optical pickup device and the optical recording / reproducing device using such a condenser lens, it is possible to improve the servo characteristics such as the focus servo, the tracking servo, and the seek time, and the optical pickup device and the optical recording / reproducing device can be reduced in size. It is possible to reduce the thickness.

The incident angle θi of the incident light to the solid immersion lens 11 is
0 ° <θi <90 °
Range.
This will be described. The numerical aperture of a condensing lens using a solid immersion lens is an optical lens 12 disposed on the opposite side of the object plane of the solid immersion lens 11 as shown in a schematic configuration diagram of an example in FIG. The incident angle from the optical axis of the incident light to the solid immersion lens 11 is θi0, the incident angle in the solid immersion lens 11 is θi, the numerical aperture of the optical lens 12 is NA, and the refractive index of the solid immersion lens 11 is n. Then
sinθi0 = NA
nsinθi0 = sinθi
Therefore, the effective numerical aperture NA (SIL) of the condenser lens including the solid immersion lens 11 is
NA (SIL) = n ² sin θi0
= Nsinθi
When θi is approximately 90 °, the effective numerical aperture of the condensing lens by the solid immersion lens 11 is maximum when NA (SIL) = n.

That is, as shown in the schematic configuration diagrams when the incident angle θi changes in FIGS. 8A to 8D, as the incident angle θi increases, the effective numerical aperture NA (SIL) of the condenser lens by the solid immersion lens increases. And approaches the maximum value n as it approaches 90 °. 7 and 8, parts corresponding to those in FIG.
That is, it is desirable to increase the incident angle θi in order to obtain a high numerical aperture, but the manufacturing margin decreases as the incident angle θi increases, and it becomes difficult to increase the yield.
For this reason, in order to secure a manufacturing margin to some extent, a configuration in which light is incident from the vicinity of the position indicated by the broken line R is desirable, that is, a practical configuration in which the incident angle θi is in the vicinity of tan ⁻¹ (n) is preferable.

Further, when the incident angle θi exceeds tan ⁻¹ (n), the holding portion 2 is provided in at least a part of the invalid region of incident light on the objective side, with the incident angle θi as a super hemisphere. Good.

Next, an example of a method for forming the solid immersion lens having the above-described configuration of the present invention will be described with reference to the process diagrams of FIGS. Raw materials suitable for the solid immersion lens described above, for example, S-LAH79 manufactured by OHARA Co., which is a high refractive index glass, Bi ₄ Ge ₃ O ₁₂ , SrTiO ₃ , which is a high refractive index ceramic, and a high refractive index single crystal material, First, as shown in FIG. 9A, a lens material body 60 made of ZrO ₂ , HfO ₂ , SiC, diamond or the like has a diameter of about 2r (ie, radius r) and a height of about r or r (1 + 1 / n). In the illustrated example, it is processed into a cylindrical shape having a height of r (1 + 1 / n). n is the refractive index of the raw material.

Next, as shown in FIG. 9B, the upper part of the height r from the upper surface of the cylindrical material is processed into a spherical shape with a radius of curvature r. That is, the processing portion 7 that is the outer portion of the upper hemisphere portion indicated by the broken line in FIG. 9B is removed by polishing or etching.
By removing the processed portion 7 in this way, as shown in FIG. 9C, the substantially hemispherical spherical portion 1 and the holding portion 2 from the position where the radius of the cross section is substantially r toward the objective side are formed. A solid immersion lens having the structure described in FIG. 6 can be formed.

FIG. 10 is a schematic configuration diagram schematically showing an optical path when incident light Li such as a laser is incident on the solid immersion lens 11 of the present invention thus formed. As is apparent from FIG. 10, the configuration of the present invention in which the cylindrical holding portion 2 is provided on the object side from the position where the radius of the cross section perpendicular to the optical axis indicated by the broken line R of the spherical portion 1 is approximately r is also used. As with the immersion lens, it can be seen that the light condensing performance can be obtained without any problem when the laser is incident.
FIG. 10 shows the case where the incident position of the laser is the position of the height r / n of the solid immersion lens, that is, the incident position from the position indicated by the broken line R. Of course, the numerical aperture (NA) is lowered more than this. Needless to say, the condensing performance can also be maintained for the incident light.
In order to increase the numerical aperture (NA), the holding unit 2 may be provided in at least a part of the invalid region of the incident light on the objective side from the incident position where the incident angle becomes maximum.

FIG. 11 shows a schematic configuration diagram of a state in which the solid immersion lens 11 and the optical lens 12 of the configuration of the present invention are combined and the solid immersion lens 11 is fixed and held on a holding body 20 such as a lens holder by bonding or the like.
The solid immersion lens according to the present invention can be easily fixed to the holding body 20 by adhesion or the like using at least a part of the holding portion 2, and there is no problem with respect to the incidence of laser. It can be seen that light collecting performance can be obtained. Therefore, it can be seen that the solid immersion lens 11 and the optical lens 12 of the configuration of the present invention can be combined and recorded and reproduced with respect to the optical recording medium 30 more stably.

  As shown in FIG. 11, the bottom surface of the holding body 20 on the object side is fixed by being separated from the surface of the optical recording medium 30 with a step of a distance g from the object surface of the solid immersion lens 11, for example. Contact of the body 20 with the optical recording medium 30 can be avoided.

In the above-described example, the holding part 2 has been described as having a cylindrical shape with a cross-sectional radius of r. However, the holding part 2 is not limited to a cylindrical shape, and various other shapes such as a square cross-sectional shape and a polygonal shape can be used. can do.
Further, the size of the cross section (radius when circular) is not required to be equal to the radius of curvature r of the spherical portion 2 as in the above example. For example, the radius r ′ of the cross section of the holding portion 2 is set to r. It is good also as '> r or r'<r.

In the example shown in FIG. 12, the spherical portion 1 has a hemispherical shape with a radius of curvature r, and has a cylindrical shape with a radius r ′ of the cross section of r ′> r in at least a part of the invalid region of incident light on the objective side. The example which provides the holding | maintenance part 2 is shown.
In the example shown in FIG. 13, the spherical portion 1 is a super hemisphere having a radius of curvature r, and a cylindrical shape having a radius r ′ of the cross section of r ′> r is held in the invalid region of incident light on the objective side. The example which provides the part 2 is shown.
In the example shown in FIG. 14, the spherical portion 1 has a hemispherical shape with a radius of curvature r, and a cylindrical holding portion 2 with a radius r ′ of the cross section r ′ <r is provided in the invalid region of incident light on the objective side. An example is shown.
In the example shown in FIG. 15, the spherical portion 1 is a super hemisphere having a radius of curvature r, and a cylindrical holding portion 2 having a radius r ′ of a cross section of r ′ <r in the invalid region of incident light on the objective side. An example of providing 12 to 15, parts corresponding to those in FIG.

In each of the above examples, by providing the holding portion 2 in the invalid region of the incident light, it is possible to provide a solid immersion lens that maintains the light collecting performance and can be stably and robustly held by the holding body. it can.
In each example, it goes without saying that the same effect can be obtained even if the shape of the holding portion 2 is various shapes other than the cylindrical shape.
Furthermore, in each example, various modifications are possible without departing from the configuration of the present invention, such as a configuration in which a convex portion is provided on an objective surface described later, or a holding processing portion is provided in the holding portion.

[2] Example of Second Embodiment Next, FIG. 16 shows an example in which the holding part 2 is provided in a part of the invalid region of the incident light of the spherical part 1 and the convex part protruding to the objective side is provided. The configuration will be described with reference to FIG. In FIG. 16, parts corresponding to those in FIG. In this example, a cylinder having an optical axis as a substantially central axis at least part of the objective side from a position (a position indicated by a broken line R) where the radius of a section perpendicular to the optical axis c of the spherical portion 1 is substantially r. This is an example in which the shape holding portion 2 is provided and the converging position on the objective side is processed into a convex cylindrical shape to form the convex portion 3.

In the solid immersion lens having the holding portion 2 as described above, the side surface of the cross-sectional shape of the holding portion 2 is substantially straight as in the example of the first embodiment described above, and complicated processing to the holding body is performed. Because it is possible to apply force evenly to this part without applying it, holding it using the holding part makes it easy and robust to hold even a small-diameter solid immersion lens that has been difficult to fix in the past. It becomes possible to do.
Further, in this case, the inclination margin with respect to the optical recording medium 30 or the like can be improved by reducing the area of the objective surface. This will be described with reference to an enlarged schematic configuration diagram of the convex portion 3 shown in FIG. 17. When the convex portion 3 is formed into a cylindrical shape having a cross-section radius perpendicular to the optical axis c and substantially y, for example, a solid immersion If the distance between the objective surface 6 of the lens 11 and the optical recording medium 30 is d, the inclination margin obtained from the angle θ1 from the condensing position of the optical recording medium 30 to the edge of the convex part 3 is tan ⁻¹ ( d / y).
As shown in FIG. 18, the inclination margin is remarkably reduced when the radius y of the object plane is increased.

For example, in the example shown in FIG. 17, the distance d between the solid immersion lens 11 and the optical recording medium 30 is 25 nm, the diameter of the objective surface 6 of the convex portion 3 is 40 μm, that is, the length y from the optical axis to the edge is set. If the thickness is 20 μm, the tilt margin is about +/− 0.07 °, the diameter is 10 μm, and the length y is 5 μm, the tilt margin is about +/− 0.28 °.
Therefore, the solid immersion lens according to the example of the second embodiment described above can be held more firmly and stably in the holding portion than the conventional one, can be reduced in size, and can improve the tilt margin. Therefore, the stability of recording / reproducing with respect to the optical recording medium can be improved.

As a method for forming such a solid immersion lens, it can be easily formed by forming the convex portion 3 on the objective side in addition to the steps described in FIGS. The step of forming the convex portion may be between or before and after each step shown in FIGS.
As a method for processing the convex portion of the objective surface of the solid immersion lens and a method for processing the flat portion around the convex portion, known etching methods and apparatuses used for semiconductor processing can be used. In particular, for processing a fine tip, it is preferable to use a focused ion beam (FIB) processing method and a processing apparatus such as a focused ion beam processing observation apparatus FB-2100 manufactured by Hitachi, Ltd., for example.
Thus, by forming the convex portion by the FIB method, the width of the object plane can be easily and reliably reduced to about several μm by an ion beam of a minute spot having a diameter of about several tens of nm. This makes it possible to easily form a solid immersion lens in which the tilt margin with respect to the optical recording medium is reliably increased as compared with the conventional case.

Further, when such a convex portion 3 is formed, by appropriately selecting the height h, the incident light Li obtained with a predetermined numerical aperture can be condensed at the condensing position without being obstructed. .
As described above, the incident light angle at which the maximum numerical aperture is obtained is 90 °. However, practically, when the refractive index of the lens material is n, the incident angle from the optical axis c is about tan ⁻¹ (n). It is desirable that
In this case, when an angle tan ⁻¹ (h / y) obtained from the height h of the convex portion 3 and the length y from the optical axis c to the edge is θ2,
θ2 <90 ° −tan ⁻¹ (n)
By doing so, the convex portion 3 on the objective side can be configured without interfering with incident light that can reliably obtain a predetermined numerical aperture.

  19 and 20, in the solid immersion lens 11 according to the example of the second embodiment described above, an incident optical path when incident light such as a laser is incident and a holder 20 such as a lens holder in combination with an optical lens. FIG. 2 shows a schematic configuration diagram of a state where the optical recording medium 30 is bonded and held and is opposed to the optical recording medium 30. 19 and 20, portions corresponding to those in FIGS. 10 and 11 are denoted by the same reference numerals, and redundant description is omitted.

As can be seen from FIG. 19, not only incident light with a predetermined numerical aperture but also incident light with a reduced numerical aperture can be condensed without any problem in the present invention, as in the case of a conventional solid immersion lens. It turns out that performance is obtained.
Further, as shown in FIG. 20, the side surface portion of the holding portion 2 of the solid immersion lens 11 can be easily fixed to the holding body 20 by adhesion or the like, and can be held stably, and incident light such as a laser can be used. It can be seen that the light condensing performance can be obtained without any problem, and that stable recording and reproduction can be performed on the optical recording medium in combination with the optical lens. Furthermore, the bottom surface on the objective side of the holding body 20 is separated from the surface of the optical recording medium 30 by a step of a distance g from the objective surface at the tip of the convex portion 3 of the solid immersion lens 11, thereby being separated from the surface of the optical recording medium 30. Contact can be avoided more.

As described above, also in the example of the second embodiment described above, it is possible to easily form a solid immersion lens having a small radius of curvature, which is the limit of the conventional solid immersion lens, and hold this lens. It can be held firmly and stably on the body.
In addition, by providing a holding part and forming a convex part on the objective side, the tilt margin between the solid immersion lens and the optical recording medium can be made larger than before, and recording / reproducing with respect to the optical recording medium is possible. It becomes possible to improve the stability of the.

  In addition, since the diameter of the solid immersion lens can be reduced and the condenser lens can be reduced in weight, it is possible to improve servo characteristics such as focus servo, tracking servo, seek time, etc. It becomes possible to reduce the size and thickness of the optical recording / reproducing apparatus.

[3] Example of Third Embodiment Next, as an example of the third embodiment, a holding portion 2 is provided on the objective side of the spherical portion 1 and a substantially prismatic convex portion protruding toward the objective side. An example in which 3 is provided will be described with reference to FIG. In FIG. 21, parts corresponding to those in FIG. 6 and FIG. In this example, a case where a prismatic convex portion 3 having a substantially square cross section is provided on the objective side of the holding portion 2 is shown.

  Even in this case, since the holding portion 2 is provided, the side surface of the cross-sectional shape of the holding portion 2 is substantially straight as in the first and second embodiments described above, and the holding body 2 is complicated. Since it is possible to apply a force evenly to this part without processing, even with a small-diameter solid immersion lens, which was difficult to hold firmly in the past, by using the holding part, It becomes possible to hold firmly.

Further, in this case, as in the example of the second embodiment, the inclination margin with respect to the optical recording medium 30 or the like can be improved by reducing the area of the objective surface.
In addition, by appropriately selecting the height of the convex portion 3 and the length from the optical axis to the edge thereof, the same light collecting performance as in the past can be maintained without interfering with incident light that obtains a predetermined numerical aperture. can do.

  The above-described first and second embodiments can be achieved by improving the recording / reproducing characteristics such as servo characteristics and reducing the size and thickness of the optical pickup device and the optical recording / reproducing device by reducing the diameter and size of the solid immersion lens. It is the same as that of the example of a form.

[4] Example of Fourth Embodiment Next, as an example of the fourth embodiment, an example in which a convex portion protruding toward the objective side is provided and the shape thereof is a cylindrical shape having a substantially elliptical cross section. The configuration will be described with reference to FIG. 22, parts corresponding to those in FIGS. 6 and 16 are denoted by the same reference numerals, and redundant description is omitted.

  In the solid immersion lens having the holding portion 2 as described above, the side surface of the cross-sectional shape of the holding portion 2 is substantially straight as in the example of the first embodiment described above, and complicated processing to the holding body is performed. Since it is possible to apply force evenly to this part without applying, even if it is a solid immersion lens with a small diameter, which was difficult to hold firmly in the past, by using the holding part, it is easy and robust. It becomes possible to hold.

Further, in this case, the inclination margin with respect to the optical recording medium 30 or the like can be improved by narrowing the area of the objective surface, particularly in one direction.
That is, in this case, the provision of the convex portion 3 can improve the tilt margin with the optical recording medium, but the length from the optical axis of the convex portion 3 to the edge is It differs in the minor axis direction and the major axis direction.

In general, when a solid immersion lens is applied to a condensing lens, an optical pickup device, and an optical recording / reproducing device for a disk-shaped optical recording medium, a tilt margin in a direction in which the disk-shaped medium is easily tilted, that is, a radial direction is further increased. It is desirable to adopt a large shape.
In the example shown in FIG. 22, the short axis direction of the elliptical section of the convex portion 3 is substantially matched with the radial direction (radial direction) indicated by the arrow Xr, and the tangential direction indicated by the arrow Xt (tangent to the recording track of the disk) If the configuration is such that the major axis direction of the elliptical cross section of the convex portion 3 substantially coincides with the optical recording medium, the tilt margin is further increased in the radial direction compared to the recording track direction of the disc. Can be great.
The same applies to the case where the convex portion 3 is provided as a prismatic shape having a rectangular cross section.

  For example, when the major axis of the convex part having an elliptical cross section is 40 μm and the minor axis is 20 μm, as shown in FIG. 23, about +/− 0.07 ° in the major axis direction and about +/− 0.07 ° in the minor axis direction. An inclination margin of +/− 0.14 ° can be obtained. Therefore, when used for a disk-shaped optical recording medium, it is possible to provide a condensing lens, an optical pickup device, and an optical recording / reproducing device having a larger inclination margin in the radial direction.

  Even in this case, since the holding portion 2 is provided, even a solid immersion lens having a small diameter, which has been difficult to hold firmly in the past, can be easily and firmly held, and the diameter and size of the solid immersion lens can be reduced. Thus, it is possible to improve the recording / reproducing characteristics such as the servo characteristics and to reduce the size and thickness of the optical pickup device and the optical recording / reproducing device as in the above-described embodiments.

  Furthermore, in this case as well, by appropriately selecting the height of the convex portion 3 and the length from the optical axis to the edge thereof, incident light that obtains a predetermined numerical aperture is not disturbed, and the same concentration as in the conventional case is used. Optical performance can be maintained.

[5] Example of Fifth Embodiment Next, an example in which the convex portion has a conical shape from the holding portion toward the objective side, a conical shape having an elliptical cross section, or a pyramid shape is illustrated in FIGS. Will be described with reference to FIG. 24 to FIG. 26, parts corresponding to those in FIG. 6 and FIG.

First, in the example shown in FIG. 24, the convex portion 3 has a conical shape from the holding portion 2 toward the objective side, and the objective surface 6 has a substantially circular shape. Such a shape can be formed relatively easily by, for example, a mechanical processing method such as polishing, etching, or the like.
And when it is set as such a structure, since the holding | maintenance part 2 of cylindrical shape etc. is provided in a part of area | region which goes to the objective surface 6 from the spherical part 1, like this in the example of each above-mentioned embodiment, The portion can be firmly and stably fixed to a holder or the like, and even a solid immersion lens having a small diameter, which has conventionally been difficult to be firmly held, can be easily and firmly held. Similar to the above-described embodiments, it is possible to improve the recording / reproducing characteristics such as servo characteristics and to reduce the size and thickness of the optical pickup device and the optical recording / reproducing device by reducing the diameter and size of the solid immersion lens. .

Further, since the area of the objective surface 6 is reduced, the tilt margin with respect to the optical recording medium can be increased as compared with the conventional case.
Even in this case, it is possible to maintain the same light collecting performance as before without disturbing incident light that obtains a predetermined numerical aperture by appropriately selecting the inclination angle of the conical portion.

In the example shown in FIG. 25, the convex part 3 is shown as a conical shape having a substantially elliptical cross section. Similar to the example shown in FIG. 24, the convex portion can be easily formed by a mechanical processing method, etching, or the like.
Even in this case, since the holding portion 2 is provided in a part of the region from the spherical portion 1 toward the object surface 6, the holding body or the like is robust and stable in this portion as in the above-described embodiments. Therefore, even a solid immersion lens having a small diameter, which has conventionally been difficult to hold firmly, can be easily and firmly held. Similar to the above-described embodiments, it is possible to improve the recording / reproducing characteristics such as servo characteristics and to reduce the size and thickness of the optical pickup device and the optical recording / reproducing device by reducing the diameter and size of the solid immersion lens. .

Further, since the area of the objective surface 6 is reduced, the tilt margin with respect to the optical recording medium can be increased as compared with the conventional case. A condensing lens having a sufficient tilt margin even in a relatively easily tilted radial direction by selecting the short axis direction of the elliptical cross section as the radial direction of the disk-shaped optical recording medium and the long axis direction as the recording track direction. An optical pickup device and an optical recording / reproducing device can be provided. In this case, the shape and size of the convex portion can be set so that the radial inclination margin is an appropriate amount larger than the tangential inclination margin.
Even in this case, it is possible to maintain the same light collecting performance as before without disturbing incident light that obtains a predetermined numerical aperture by appropriately selecting the inclination angle of the conical portion.

In the example shown in FIG. 26, an example is shown in which the convex portion 3 is formed in a pyramid shape with a substantially square cross section. Such a shape can also be easily formed by a mechanical processing method or an etching method.
Even in this case, since the holding portion 2 is provided in a part of the region from the spherical portion 1 toward the object surface 6, the holding body or the like is robust and stable in this portion as in the above-described embodiments. Therefore, even a solid immersion lens having a small diameter, which has conventionally been difficult to hold firmly, can be easily and firmly held. Similar to the above-described embodiments, it is possible to improve the recording / reproducing characteristics such as servo characteristics and to reduce the size and thickness of the optical pickup device and the optical recording / reproducing device by reducing the diameter and size of the solid immersion lens. .
Further, since the area of the objective surface 6 is reduced, the tilt margin with respect to the optical recording medium can be increased as compared with the conventional case.
Furthermore, by appropriately selecting the inclination angle of the pyramid-shaped portion, it is possible to maintain the same light collecting performance as before without hindering incident light that obtains a predetermined numerical aperture.
In the example shown in FIG. 22, the pyramid shape is a quadrangular pyramid shape, but, of course, a pyramid shape having a polygonal cross section such as a hexagonal pyramid or an octagonal pyramid may be used.

[6] Example of Sixth Embodiment Next, an example in which the convex portion 3 is configured as a curved surface or a spherical surface protruding from the holding portion 2 toward the object side will be described with reference to FIG. 27, parts corresponding to those in FIG. 6 and FIG.
Even in such a shape, the convex portion can be formed relatively easily by a mechanical processing method such as polishing.

  Also in this case, the holding part 2 is provided in a part of the invalid region of the incident light from the spherical part 1 toward the objective surface 6 as in the above-described embodiments. In addition, it can be stably fixed to a holding body and the like, and even a solid immersion lens having a small diameter, which has conventionally been difficult to hold firmly, can be easily and firmly held. Similar to the above-described embodiments, it is possible to improve the recording / reproducing characteristics such as servo characteristics and to reduce the size and thickness of the optical pickup device and the optical recording / reproducing device by reducing the diameter and size of the solid immersion lens. .

Further, since the area of the objective surface 6 is reduced, the tilt margin with respect to the optical recording medium can be increased as compared with the conventional case.
Furthermore, by appropriately selecting the curvature of the curved surface portion, it is possible to maintain the same light collecting performance as in the past without hindering incident light that obtains a predetermined numerical aperture.
In addition, in the example shown in FIG. 27, although the convex-shaped part 3 is made into substantially spherical shape, it can be set as various other curved surface shapes.

  Further, in the case where the vicinity of the object plane 6 has a shape circumscribing a sphere indicated by a broken line b whose radius is approximately r / n and whose center position substantially coincides with the center position of the spherical portion 1, Even when the incident angle of incident light slightly deviates in the vicinity of the light position, since the distance passing through the lens can be made substantially constant, the advantage that light can be reliably collected on the objective surface 6 of the lens. Have

In each configuration including the above-described embodiments, the shape of the object surface 6 circumscribing the sphere indicated by the broken line b whose radius is approximately r / n and whose center position is substantially coincident with the center position of the spherical portion 1 is thus obtained. Needless to say, the same effect can be obtained.
In each of the examples, the spherical portion 1 may be a hemisphere instead of a super hemisphere, and in this case, a shape that substantially circumscribes a sphere having a diameter of approximately r in the vicinity of the light collection position of the objective surface 6 Thus, similarly, even when the incident angle of the incident light is slightly deviated, the distance passing through the lens can be made substantially constant, so that the light can be reliably condensed on the objective surface 6 of the lens. Has the advantage.
Further, in these examples, even when the radius is slightly deviated from r / n or r / 2 or circumscribed slightly with respect to a sphere having the radius r / n or r / 2, the incident light is incident. On the side, the same effect can be obtained as long as this can be corrected.

[7] Example of Seventh Embodiment Next, referring to FIG. 28 to FIG. 30, in the solid immersion lens according to the present invention, the holding processing portion 4 is formed on at least a part of the side surface of the holding portion 2. Each example will be described. 28 to 30, portions corresponding to those in FIGS. 6 and 16 are denoted by the same reference numerals, and redundant description is omitted. In each example, the case where the spherical portion 1 is a super hemisphere is shown. However, similarly to each of the above examples, the spherical portion 1 may be a hemisphere, and the thickness along the optical axis may be r.

First, in the example shown in FIG. 28, a case is shown in which a concave portion having a substantially square cross section is provided on a part of the side surface of the holding portion 2 to form the holding processing portion 4.
Further, in the example shown in FIG. 29, a case is shown in which the holding processing portion 4 is formed by providing a curved concave portion having a smooth cross section in a part of the side surface of the holding portion 2.
Further, FIG. 30 shows an example in which a roughening process is performed on a part of the side surface of the holding unit 2 as the holding processing unit 4.
In each of these examples, the holding processing section 4 having various shapes may be intermittently formed on a part of the side surface of the holding section 2, or as a continuous groove-shaped recess or line-shaped rough surface section. It may be formed.
In each example, the case where the cylindrical convex portion 3 is provided on the objective side of the holding portion 2 is shown, but the objective side may be planar, and the spherical portion 1 may be hemispherical, or Needless to say, the present invention can be applied to the case where convex portions having various shapes such as the shapes described in the third to sixth embodiments are provided.

As described above, by providing the holding processing portion 4 on the side surface of the holding portion 2, it is possible to more firmly and stably fix the adhesive by adhesion to the holding body. In the case where the concave portion is provided, a stronger fixing can be performed by providing a convex portion on the holding body to be a fitting type.
Therefore, even a solid immersion lens with a small diameter, which has been difficult to maintain in the past, can be held easily and robustly, and the recording / reproducing characteristics such as servo characteristics are improved by reducing the diameter and size of the solid immersion lens. The optical pickup device and the optical recording / reproducing device can be reduced in size and thickness in the same manner as in the embodiments described above.

  As described above, according to the solid immersion lens of the present invention, it is possible to sufficiently fix the lens holder or the like with a holding body such as a lens holder. It is possible to improve focus servo characteristics, tracking servo characteristics, and seek characteristics in lenses, optical pickup devices, and optical recording / reproducing devices. By adopting a near-field recording / reproducing method, optical recording media can be increased in density and size. It becomes possible to cope with capacity increase.

In addition, in the solid immersion lens of the present invention, by providing a convex portion on the objective side of the holding portion, the tilt margin between the solid immersion lens and the optical recording medium can be improved, and recording and reproduction with respect to the optical recording medium are stable. Therefore, it is possible to provide an optical pickup apparatus and an optical recording / reproducing apparatus more suitable for the near-field recording / reproducing system.
As described above, the solid immersion lens according to the present invention is not limited to the above-described example, and various modifications and changes can be made in other material configurations and the like without departing from the configuration of the present invention. Needless to say.

It is a schematic block diagram of an example of the solid immersion lens and condensing lens by this invention. It is a schematic block diagram of an example of the condensing lens by this invention. It is a schematic block diagram of an example of the optical pick-up apparatus by this invention. It is a schematic block diagram of an example of the optical pick-up apparatus by this invention. It is a schematic block diagram of an example of the optical pick-up apparatus by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram with which it uses for description of the numerical aperture of a solid immersion lens. A is a schematic block diagram of an example of a solid immersion lens. B is a schematic configuration diagram of an example of a solid immersion lens. C is a schematic configuration diagram of an example of a solid immersion lens. D is a schematic configuration diagram of an example of a solid immersion lens. FIG. 4A is a process diagram of an example of a method for forming a solid immersion lens of the present invention. B is a process diagram of an example of a method for forming a solid immersion lens of the present invention. FIG. C is a process diagram of an example of a method for forming a solid immersion lens of the present invention. FIG. It is a schematic block diagram which shows the incident aspect of the incident light of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the condensing lens which has a solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of the principal part of an example of the solid immersion lens by this invention. It is a figure which shows the inclination margin with respect to the diameter of the convex part of a solid immersion lens. It is a schematic block diagram which shows the incident aspect of the incident light of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the condensing lens which has a solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a figure which shows the inclination margin with respect to the diameter of the convex part of a solid immersion lens. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the solid immersion lens by this invention. It is a schematic block diagram of an example of the conventional solid immersion lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Spherical part, 2 ... Holding part, 3 ... Convex part, 4 ... Processing part for holding, 6 ... Objective surface, 7 ... Processing part, 11 ... Solid immersion lens, 12 ... Optical lens, 13 ... Condensing lens, DESCRIPTION OF SYMBOLS 14 ... 1st beam splitter, 15 ... 2nd beam splitter, 16 ... Biaxial actuator, 17 ... Coil for tracking, 18 ... Coil for focusing, 20 ... Holding body, 21 ... Slider, 22 ... Gimbal, 23 ... Mirror 30 ... Optical recording medium

Claims (15)

A solid immersion lens, wherein a holding portion having a straight line in a cross-sectional shape along the optical axis is provided in at least a part of an ineffective region of incident light. 2. The solid immersion lens according to claim 1, wherein a convex portion is formed on the objective side of the holding portion. 3. The solid immersion lens according to claim 2, wherein the convex portion has a cylindrical shape protruding toward the objective side, a cylindrical shape having an elliptical cross section, or a prism shape. 3. The solid immersion lens according to claim 2, wherein the convex portion has a conical shape from the holding portion toward the objective side, a conical shape having an elliptical cross section, or a pyramid shape. The solid immersion lens according to claim 2, wherein the convex portion has a curved surface shape or a spherical shape protruding from the holding portion toward the objective side. The solid immersion lens according to claim 1, wherein a holding processing portion is formed on at least a part of the holding portion. The solid immersion lens according to claim 2, wherein a holding processing portion is formed on at least a part of the holding portion. The solid immersion lens according to claim 3, wherein a holding processing portion is formed on at least a part of the holding portion. The solid immersion lens according to claim 4, wherein a holding processing portion is formed on at least a part of the holding portion. 6. The solid immersion lens according to claim 5, wherein a holding processing portion is formed on at least a part of the holding portion. In a condensing lens composed of a solid immersion lens and an optical lens that is aligned with the optical axis of the solid immersion lens and disposed on the side opposite to the objective side,
The solid immersion lens is a condensing lens, wherein a holding portion having a straight line in a cross-sectional shape along the optical axis is provided in at least a part of an ineffective region of incident light. A solid immersion lens, an optical lens arranged on the opposite side of the objective side so as to coincide with the optical axis of the solid immersion lens, and a light source are provided at least, and by a condensing lens comprising the solid immersion lens and the optical lens In an optical pickup device that forms a light spot by converging light emitted from the light source,
The solid immersion lens is an optical pickup device comprising a holding portion having a straight line in a cross-sectional shape along the optical axis in at least a part of an ineffective region of incident light. A solid immersion lens, an optical lens arranged on the opposite side of the objective side so as to coincide with the optical axis of the solid immersion lens, and a light source are provided at least, and by a condensing lens comprising the solid immersion lens and the optical lens It has an optical pickup device that forms a light spot by converging the light emitted from the light source, and is provided with control drive means for controlling and driving the condenser lens in the focusing direction and / or the tracking direction of the optical recording medium. In an optical recording / reproducing apparatus,
The solid immersion lens is an optical recording / reproducing apparatus characterized in that a holding portion having a straight line in a cross-sectional shape along the optical axis is provided in at least a part of an ineffective region of incident light. In the method of forming a solid immersion lens,
Processing the lens material body into a cylindrical shape;
And a step of forming a spherical portion having a radius of curvature r in a part of the lens material body. 15. The method for forming a solid immersion lens according to claim 14, further comprising a step of forming a convex portion on the objective side of the lens material body.

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