WO2016125252A1

WO2016125252A1 - Hologram recording and reproduction device, and method for correcting optical axis of optical component used for same

Info

Publication number: WO2016125252A1
Application number: PCT/JP2015/052969
Authority: WO
Inventors: 和良山崎
Original assignee: 日立コンシューマエレクトロニクス株式会社
Priority date: 2015-02-03
Filing date: 2015-02-03
Publication date: 2016-08-11

Abstract

The purpose of the present invention is to provide a hologram recording and reproduction device capable of carrying out stable recording and reproduction, or reproduction by correcting the angular displacement, the inclination of an optical axis associated with a positional displacement, and a positional displacement of an optical component in the optical system in the hologram recording and reproduction device. For this purpose, a two-beam angle multiplexing hologram recording and reproduction device comprises: a light source unit for emitting an optical beam; a divergence unit for diverging the optical beam emitted from the light source into signal light and reference light; a first lens for irradiating an optical information recording medium with the signal light; a second lens for causing the reference light to be incident onto substantially the same position as the position onto which the signal light is incident in the optical information recording medium; a light path angle changing unit for changing the incident angle of the reference light incident on the optical information recording medium; and an optical component in the light path from the light source to the first lens or the second lens. The hologram recording and reproduction device also comprises an optical axis changing unit for changing the inclination or the position of the incident light on the optical component.

Description

Hologram recording / reproducing apparatus and optical axis correction method for optical component used therefor

The present invention relates to a hologram recording / reproducing apparatus, and more particularly to a method for correcting the optical axis of incident light of an optical component in a hologram recording / reproducing apparatus of a two-beam angle multiplexing system.

The holographic memory is a system that causes signal light and reference light to interfere with each other and records the interference fringes as a hologram on an optical information recording medium. For example, in the two-beam angle multiplexing system, the hologram is multiplexed and recorded by changing the incident angle of the reference light at the same position on the optical information recording medium. At the time of reproduction, the reference light is incident on the optical information recording medium at the same incident angle as that at the time of recording, and the information recorded on the optical information recording medium is reproduced by detecting the reproduction light diffracted from the hologram by the imaging device.

Generally, in the holographic memory, the recording density can be improved by increasing the number of multiplexing and reducing the size of the hologram on the optical information recording medium. In the two-beam angle multiplexing system, the recording density can be further improved by reducing the distance between adjacent holograms on the medium.

As a background art in this technical field, there is, for example, JP 2010-129134 A (Patent Document 1). In Patent Document 1, as a problem, “the objective lens and the optical axis position of the laser beam can be kept constant even if the objective lens is driven without the objective lens and the rising mirror being integrated. There is a description that “a hologram recording apparatus and a hologram reproducing apparatus that can suppress the cost increase without providing a large driving mechanism in the apparatus”, and “in front of the entrance pupil plane of the objective lens on the optical path of the information laser light” is described as a solution. It is installed in front of the entrance pupil plane of the objective lens on the optical path of the information laser light, and a plate-like object having a refractive index different from that of air, which changes the optical axis position of the information laser light by driving. An optical path length varying optical component that varies the optical path length of the information laser beam, and a drive that detects the driving amount of the objective lens from the neutral position in the radial direction of the hologram recording medium by the tracking servo means. The amount detecting means, the optical axis position varying means for driving the plate-like object with the detected driving amount, and the optical path length varying means for driving the optical component for varying the optical path length with the detected driving amount. Yes.

JP 2010-129134 A

In order to realize stable recording / reproduction in the holographic memory, high angular accuracy and positional accuracy are required. In addition, a uniform intensity distribution and good wavefront aberration are required. However, in an actual holographic memory device, there is a problem in that the optical component causes an angular deviation and a positional deviation that cause deterioration in recording and reproducing performance due to disturbances such as temperature, humidity, and vibration (hereinafter referred to as disturbances) and changes with time. There is.

Patent Document 1 discloses a shift multiplex type hologram recording / reproducing apparatus that uses an optical axis position variable means installed in front of an entrance pupil plane of an objective lens to track the objective lens without integrating the objective lens and the rising mirror. The optical axis position is controlled by the optical axis position variable means so that the relationship between the objective lens and the optical axis position of the laser beam is kept constant following the change in the relative position with the recording medium by the servo. That is, an optical axis position varying means installed in front of the entrance pupil plane of the objective lens, corresponding to a relative position change between the objective lens and the recording medium peculiar to the shift multiplexing system is disclosed. However, in the case of Patent Document 1, no consideration is given to the case where angular deviation or positional deviation of individual optical components in the optical path leading to the objective lens occurs, and since these cannot be corrected, the recording / reproducing performance deteriorates. It becomes a problem.

The present invention is a hologram recording / reproducing apparatus or an optical system in the hologram reproducing apparatus, which corrects the angle deviation of the optical component, the inclination of the optical axis accompanying the position deviation, and the position deviation, and can perform stable recording or reproduction. It is an object of the present invention to provide a reproducing apparatus and an optical axis correction method for optical components used therefor.

In order to solve the above problems, for example, the configuration described in the claims is adopted. The present invention includes a plurality of means for solving the above-mentioned problems. For example, a two-beam angle multiplexing type hologram recording / reproducing apparatus, which includes a light source unit that emits a light beam, and a light source unit that emits light from the light source unit. A branching portion for branching the light beam into signal light and reference light, a first lens portion for irradiating the optical information recording medium with signal light, and reference light at substantially the same position as the signal light in the optical information recording medium In the optical path from the light source unit to the first lens unit or the second lens unit, and the optical path angle variable unit for changing the incident angle of the reference light incident on the optical information recording medium. And an optical axis variable unit that changes the inclination or position of the incident light on the optical component.

According to the present invention, a hologram recording / reproducing apparatus capable of performing stable recording or reproduction by correcting optical axis tilt and positional deviation caused by positional deviation and angular deviation of optical components, and optical axis correction of optical components used therefor. A method can be provided.

1 is a configuration diagram of a hologram recording / reproducing apparatus in Embodiment 1. FIG. 1 is a configuration diagram of an optical pickup device and a phase conjugate optical system in a hologram recording / reproducing apparatus in Embodiment 1. FIG. It is a figure explaining the optical axis variable part 35 in Example 1. FIG. 6 is a diagram illustrating another configuration of the optical axis variable unit 35 in Embodiment 1. FIG. 6 is a configuration diagram of another optical pickup device in Embodiment 1. FIG. 6 is a diagram illustrating another configuration of the optical axis variable unit 35 in Embodiment 1. FIG. FIG. 10 is a diagram illustrating still another configuration of the optical axis variable unit 35 in the first embodiment. 5 is a configuration diagram of an optical pickup device in Embodiment 2. FIG. 6 is a configuration diagram of an optical pickup device in Embodiment 3. FIG. It is a figure explaining the optical axis variable part 120 in Example 3. FIG. 6 is a configuration diagram of an optical pickup device in Embodiment 4. FIG. FIG. 10 is a configuration diagram of an optical pickup device in Embodiment 5. It is a figure explaining the optical axis variable part 15 in Example 5. FIG. FIG. 10 is a configuration diagram of an optical pickup device in Example 6. FIG. 10 is a diagram illustrating an intensity distribution conversion lens 16 in Example 6. FIG. 10 is a diagram illustrating an adjustment medium 301 in Embodiment 6. It is a figure explaining another detection method in Example 6. FIG. FIG. 10 is a configuration diagram of an optical pickup device in Example 7. FIG. 10 is a diagram illustrating a reference light correction method according to a seventh embodiment. FIG. 10 is a diagram illustrating an adjustment flow in Example 8. It is a figure which shows the adjustment flow in Example 9. FIG.

FIG. 1 shows an overall configuration of a hologram recording / reproducing apparatus according to the present embodiment. The hologram recording / reproducing apparatus includes, for example, an optical pickup device 60, a phase conjugate optical system 512, an optical information recording medium Cure optical system 513, and an optical information recording medium driving element 70 shown in FIG.

The optical pickup device 60 plays a role of emitting reference light and signal light to the optical information recording medium 300 and recording digital information using a hologram. At this time, the information signal to be recorded is sent to the spatial light modulator (SLM) 25 in the optical pickup device 60 by the controller 89 via the signal generation circuit 86, and the signal light is modulated by the spatial light modulator 25. When reproducing information recorded on the optical information recording medium 300, the phase conjugate light of the reference light emitted from the optical pickup device 60 is generated by the phase conjugate optical system 512. Here, the phase conjugate optical system 512 indicates, for example, the galvanometer mirror 51 of FIG. The phase conjugate light is a light beam that travels in the opposite direction while maintaining the same wavefront as the input light.

The reproduction light reproduced by the phase conjugate light is detected by the image sensor 52 in the optical pickup device 60, and the signal is reproduced by the signal processing circuit 85. The irradiation time of the reference light and the signal light applied to the optical information recording medium 300 can be adjusted by controlling the opening / closing time of the shutter in the optical pickup device 60 via the shutter control circuit 87 by the controller 89.

The Cure optical system 513 plays a role of generating a light beam used for pre-cure and post-cure of the optical information recording medium 300. Here, the pre-cure is a pre-process in which, when information is recorded at a desired position in the optical information recording medium 300, a predetermined light beam is irradiated in advance before the reference light and signal light are irradiated to the desired position. . Post-cure is a post-process in which, after recording information at a desired position in the optical information recording medium 300, a predetermined light beam is irradiated so that the desired position cannot be additionally recorded.

A predetermined light source driving current is supplied from the light source driving circuit 82 to the light sources in the optical pickup device 60 and the optical information recording medium Cure optical system 513, and each light source can emit a light beam with a predetermined light amount.

Further, when an optical axis tilt or position shift occurs due to a change in temperature or temperature in the optical pickup device 60, the optical axis tilt or position shift is detected, and the optical axis variable unit control circuit 90 detects the optical axis tilt or position shift. The optical axis variable unit in the optical pickup device 60 is driven to correct the optical axis inclination and positional deviation.

Here, the optical pickup device 60, the phase conjugate optical system 512, and the optical information recording medium Cure optical system 513 are shown independently. However, some optical system configurations or all optical system configurations may be simplified as one. It doesn't matter.

FIG. 2 shows the optical pickup device 60 and the phase conjugate optical system 512 in the hologram recording / reproducing apparatus of the two-beam angle multiplexing system of this embodiment. The recording / reproducing method of this embodiment will be described with reference to FIG.

First, the recording method of this embodiment will be described. The light beam emitted from the light source 10 passes through the collimator lens 11 and is converted into a desired beam diameter, and then passes through the relay lens 13 and the pinhole 14 disposed in the relay lens 13. In hologram recording / reproduction, the non-uniformity of the intensity distribution deteriorates the recording / reproduction performance. Therefore, in this embodiment, unnecessary frequency components are removed from the intensity distribution of the light beam using the relay lens 13 and the pinhole 14.

The light beam emitted from the relay lens 13 enters the intensity distribution conversion lens 16. The intensity distribution conversion lens 16 functions as an intensity distribution conversion unit, and is a lens that converts an intensity distribution of a substantially Gaussian distribution into a uniform intensity distribution having a top hat shape. As described above, in hologram recording / reproduction, it is desirable that the intensity distribution of the light beam be uniform. Therefore, in this embodiment, the intensity distribution conversion lens 16 is used to realize a uniform intensity distribution. The light beam emitted from the intensity distribution conversion lens 16 enters the polarization variable element 18 through the shutter 17. The light beam incident on the polarization variable element 18 is converted by the polarization variable element 18 into polarized light including a P polarization component and an S polarization component. The polarization variable element 18 is an element that converts the light into predetermined polarized light according to recording or reproduction. The polarization variable element 18 of this embodiment converts the emitted light into polarized light including a P-polarized component and an S-polarized component during recording, and converts it into S-polarized light during reproduction.

The light beam emitted from the polarization variable element 18 enters the PBS prism 19, and the P-polarized component is transmitted and the S-polarized component is reflected. Here, the light beam transmitted through the PBS prism 19 is called signal light, and the reflected light beam is called reference light. The optical path from the light source 10 to the PBS prism 19 is a common optical path, the optical path from the PBS prism 19 to the optical information recording medium 300 via the spatial light modulator 25 is a signal optical path, and the galvanomirror 51 from the PBS prism 19 to the galvanomirror 37. The optical path leading to is called the reference optical path.

The signal light transmitted through the PBS prism 19 enters the beam expander 21 and is converted into a desired beam diameter. The signal light transmitted through the beam expander 21 enters the spatial light modulator 25 through the phase mask 22, the relay lens 23, and the PBS prism 24. The spatial light modulator 25 is an optical element that adds two-dimensional data to signal light.

The signal light to which information is added by the spatial light modulator 25 is reflected by the PBS prism 24 and enters the opening 27 in the relay lens 26 via the relay lens 26. The opening 27 is disposed for the purpose of removing the high frequency component of the signal light added by the spatial light modulator 25 in order to increase the recording density of the optical information recording medium 300. The signal light emitted from the opening 27 is condensed in the optical information recording medium 300 through the objective lens 29.

On the other hand, the reference light reflected from the PBS prism 19 passes through the mirror 32, the mirror 33, the half-wave plate 34, the optical axis variable unit 35, the pitch collector 36, the galvano mirror 37, and the scanner lens 39, and the optical information recording medium 300. Is incident on. Here, the galvanometer mirror 37 functions as an optical path angle changing unit for changing the incident angle of the reference light incident on the optical information recording medium, and changes the mirror angle with the rotation axis P as the rotation axis, thereby changing the angle of the mirror. The incident angle can be changed. In addition, the scanner lens 39 is a lens that allows reference light having a predetermined angle reflected by the galvanometer mirror 37 to be incident at substantially the same position in the optical information recording medium 300 at a predetermined angle. Thereby, angle multiplexing can be realized at substantially the same position in the optical information recording medium 300 using the galvanometer mirror 37 and the scanner lens 39. The pitch collector 36 can tilt the optical axis of the incident reference light in a direction perpendicular to the direction in which the galvanometer mirror 37 tilts. Thus, even when the optical information recording medium 300 is mounted with an inclination, the inclination can be corrected by using the galvanometer mirror 37 and the pitch collector 36.

At this time, the signal light of the convergent light and the reference light of the parallel light are incident on the optical information recording medium 300 so as to overlap each other. Thereby, interference fringes are formed in the optical information recording medium 300, and the interference fringes are recorded as holograms on the recording material in the optical information recording medium 300.

After the information is recorded in the optical information recording medium 300, the shutter 17 is closed, and the information recorded in the optical information recording medium 300 is displayed by the spatial light modulator 25. At the same time, the galvanometer mirror 37 rotates by a small amount, and the incident angle of the reference light to the optical information recording medium 300 is changed. Thereafter, when the shutter 17 is opened, the next two-dimensional data is recorded at substantially the same position in the optical information recording medium 300. This is repeated to perform angle multiplex recording. When the predetermined multiplexing number is reached, the position of the optical information recording medium 300 is moved, and further recording is performed. Here, each piece of information recorded by angle multiplexing at substantially the same position is called a page, and an area recorded by angle multiplexing is called a book.

Next, the playback method will be described. The light beam emitted from the light source 10 passes through the collimator lens 11 and is converted into a desired beam diameter, and then passes through the relay lens 13, the pinhole 14 in the relay lens 13, the intensity distribution conversion lens 16, and the shutter 17, and then polarized. The light enters the variable element 18. Then, the light beam is converted into S-polarized light by the polarization variable element 18 and reflected by the PBS prism 19. The reference light reflected from the PBS prism 19 is mirror 32, mirror 33, half-wave plate 34, optical axis variable section 35, pitch collector 36, galvano mirror 37, scanner lens 39, optical

information recording medium

300, 1/4. The light enters the galvanometer mirror 51 through the wave plate 50.

The galvanometer mirror 51 is controlled by the controller 89 so that the incident reference light is substantially perpendicular to the galvanometer mirror 51. The incident reference light is reflected in a substantially opposite direction, passes through the quarter-wave plate 50, and The light enters the optical information recording medium 300 again. Here, when the reference light is incident on a predetermined book in the optical information recording medium 300, reproduction light that is diffracted light is generated from the hologram in the optical information recording medium 300.

Reproduced light enters the image sensor 52 through the objective lens 29, the relay lens 26, the opening 27 in the relay lens, and the PBS prism 24. Then, two-dimensional data is reproduced based on the reproduction light incident on the image sensor 52.

Next, the galvanometer mirror 37 and the galvanometer mirror 51 are rotated by a minute amount, and the incident angle of the reference light to the optical information recording medium 300 is changed. Thereby, two-dimensional data of different pages in the same book is reproduced by the image sensor 52. When the predetermined number of pages have been reproduced, the position of the optical information recording medium 300 is moved and the next book is reproduced.

In such a hologram recording / reproducing apparatus, in this embodiment, stable optical recording / reproducing is performed by correcting optical component positional deviation, optical axis inclination and positional deviation caused by angular deviation in the optical system in the hologram recording / reproducing apparatus. Alternatively, a hologram recording / reproducing apparatus or a hologram reproducing apparatus that can perform reproduction is provided.

In order to ensure the recording performance of the hologram recording / reproducing apparatus, it is necessary to suppress the relative displacement between the irradiation positions of the signal light and the reference light in the optical information recording medium 300 to a predetermined amount or less. However, since the actual hologram recording / reproducing apparatus has a large number of optical components and a long optical path length, the relative displacement between the irradiation positions of the signal light and the reference light in the optical information recording medium 300 can be achieved only by mounting the optical components. It is difficult to manage below a predetermined amount. Therefore, in this embodiment, the relative positional deviation between the irradiation positions of the signal light and the reference light in the optical information recording medium 300 at the time of recording is corrected. Hereinafter, the correction means will be described. Hereinafter, the relative positional deviation between the irradiation position of the signal light and the reference light in the optical information recording medium 300 is referred to as the relative positional deviation between the signal light and the reference light in the optical information recording medium 300.

¡If there is an angular shift or misalignment of the optical component due to disturbance or changes over time, it is ideally corrected for each component. However, since there are actually a large number of optical components in the hologram recording / reproducing apparatus, it is not possible to correct all the optical components that are misaligned or misaligned. Therefore, in this embodiment, an optical axis variable unit that corrects the optical axis inclination and the positional deviation caused by the angular deviation and positional deviation of the optical component is arranged in the hologram recording / reproducing apparatus.

Hereinafter, a method for correcting the relative positional deviation between the signal light and the reference light in the optical information recording medium 300 during recording will be described. FIG. 3 shows a correction method of the optical axis variable unit 35 of the present embodiment. FIGS. 3A-1 and 3A-2 show the initial state, and FIGS. 3B-1 and 2B-2 show the position of the reference light incident on the galvanomirror 37 due to disturbance or change over time. (C-1) and (C-2) show the corrected states. (A-1), (B-1), and (C-1) are the optical axis variable unit 35, the parallel plate 105 in the optical axis variable unit 35, the galvanometer mirror 37, the scanner lens 39 and the positional relationship thereof. The reference beam R and the optical axis R1 of the reference beam R are shown, and the alternate long and short dash line in the figure shows the central axis Q of the scanner lens 39. Also, (A-2), (B-2), and (C-2) show the positional relationship between the signal light S and the reference light R in the recording material portion in the optical information recording medium 300.

Originally, it is desirable that the irradiation position S1 of the signal light S and the irradiation position R2 of the reference light R in the recording material portion in the optical information recording medium 300 coincide with each other as shown in FIG. Therefore, in the initial state, it is assumed that the optical axis R1 of the reference light and the central axis Q of the scanner lens 39 are aligned as shown in FIG. When the position of the optical axis R1 of the reference light R incident on the galvanometer mirror 37 is shifted as shown in (B-1) due to disturbance or change with time from this state, the optical information as shown in (B-2). The irradiation position S1 of the signal light S and the irradiation position R2 of the reference light R of the recording material portion in the recording medium 300 are shifted. On the other hand, (C-1) inclines the parallel plate 105 with respect to the optical axis from the state (B-1). The optical axis variable unit 35 of this embodiment includes at least a parallel plate 105 and a rotation mechanism, and the parallel plate 105 is emitted from the parallel plate 105 by being inclined with respect to the optical axis of the reference light by the rotation mechanism. The optical axis of light can be displaced in the parallel direction. Thereby, the position of the reference light incident on the galvanometer mirror 37 can be made the same position as the initial state, and as a result, the signal light S of the recording material portion in the optical information recording medium 300 as shown in (C-2). The irradiation position S1 and the irradiation position R2 of the reference light R can be matched.

As described above, in this embodiment, the relative position shift between the signal light and the reference light in the optical information recording medium 300 is corrected by displacing the optical axis of the reference light incident on the optical information recording medium 300 in the parallel direction. . This makes it possible to perform stable recording and reproduction even when there are disturbances and changes with time.

In the present embodiment, the parallel plate 105 in the optical axis variable unit 35 is tilted with respect to the optical axis of the reference light, thereby displacing the optical axis of the reference light in the parallel direction and the signal light in the optical information recording medium 300. The relative positional deviation of the reference beam was corrected. However, the correction method is not limited thereto, and the relative position shift between the signal light and the reference light in the optical information recording medium 300 may be corrected by tilting the optical axis of the reference light using the optical axis variable unit 35. For example, it can be realized by changing the parallel plate 105 to the wedge prism 104 as shown in FIG. Note that the wedge prism 104 is characterized in that the optical axis of the reference light emitted from the wedge prism 104 can be tilted by being inclined with respect to the optical axis of the reference light.

4 (A-1) and (A-2) show the initial state, and (B-1) and (B-2) show the position of the reference light incident on the galvanomirror 37 due to disturbance and changes over time. (C-1) and (C-2) show the corrected states. (A-1), (B-1), and (C-1) are the positional relationship between the optical axis variable unit 35, the wedge prism 104, the galvano mirror 37, and the scanner lens 39 in the optical axis variable unit 35, and The reference beam R and the optical axis R1 of the reference beam R are shown, and the alternate long and short dash line in the figure shows the central axis Q of the scanner lens 39. Also, (A-2), (B-2), and (C-2) show the positional relationship between the signal light S and the reference light R in the recording material portion in the optical information recording medium 300.

When the position of the reference light incident on the galvano mirror 37 is shifted as shown in FIG. 4 (B-1) due to disturbance or changes with time, the recording material portion in the optical information recording medium 300 is shown in (B-2). The irradiation position S1 of the signal light S is shifted from the irradiation position R2 of the reference light R. Therefore, in this embodiment, the optical axis of the reference light is inclined by inclining the wedge prism 104 with respect to the optical axis, and the position of the reference light incident on the galvano mirror 37 is changed as shown in (C-1). Thereby, the irradiation position S1 of the signal light S and the irradiation position R2 of the reference light R of the recording material portion in the optical information recording medium 300 can be matched as shown in (C-2). In this case, there is a problem that the angle of the reference light reflected from the galvanometer mirror 37 changes according to the inclination of the optical axis of the emitted light of the reference light from the wedge prism 104. On the other hand, by adding the incident angle as a correction amount of the galvanometer mirror 37 in advance during recording / reproducing, recording / reproducing similar to the case of the parallel plate 105 can be performed. In addition, the wedge prism 104 has a feature that the amount of change in the tilt of the optical axis with respect to the tilt amount of the wedge prism 104 is small, so that the correction can be performed with high accuracy. Furthermore, there is an advantage that the correction range can be made larger than that of the parallel plate 105 by increasing the distance between the wedge prism 104 and the galvanometer mirror 37.
3 and 4 assume that the incident position of the reference light on the galvano mirror 37 is shifted due to disturbances and changes with time of the optical component, but the present invention is not limited to this. For example, when the irradiation position of the signal light in the optical information recording medium 300 is shifted due to the positional shift of the objective lens 29 or the like, the incident position of the reference light on the galvano mirror 37 intentionally using the optical axis variable unit 35. Can be used to correct the relative positional deviation between the signal light and the reference light in the optical information recording medium 300.

However, when the deviation of the irradiation position of the signal light in the optical information recording medium 300 is large, the following problem is newly born. That is, when the deviation of the irradiation position of the signal light in the optical information recording medium 300 is large, in order to correct the relative positional deviation between the signal light and the reference light in the optical information recording medium 300, the reference light to the galvanometer mirror 37 is corrected. It is necessary to greatly shift the incident position from the initial position. In this case, when the galvanometer mirror 37 is rotated during recording and reproduction, there is a problem that the irradiation position of the reference light in the optical information recording medium 300 changes accordingly. In order to solve this problem, an optical axis variable unit 38 may be disposed between the galvanometer mirror 37 and the scanner lens 39 as shown in FIG. The optical axis variable unit 38 includes a parallel plate and at least a rotation mechanism. When the parallel plate is inclined with respect to the reference light by the rotation mechanism, the reference light emitted from the optical axis variable unit 38 is used as the optical axis. On the other hand, it can be displaced in a parallel direction. The optical axis correction element 38 corrects the relative positional deviation between the signal light and the reference light in the optical information recording medium 300. Further, the optical axis correction element 38 corrects the positional deviation of the reference light incident on the galvano mirror 37, so that the relative position of the signal light and the reference light in the optical information recording medium 300 even when the galvano mirror 37 rotates. Deviation can be reduced.

Here, the relative positional deviation between the signal light and the reference light in the optical information recording medium 300 is corrected using the optical axis variable unit 35 and the optical axis variable unit 38. The relative positional deviation between the signal light in 300 and the reference light may be corrected.

The driving method of the optical axis variable unit 35 and the optical axis variable unit 38 may be a stepping motor, a linear actuator, or the like, or may be manual or other.

In the present embodiment, the optical axis of the reference light is displaced in the parallel direction by inclining the parallel plate 105 of the optical axis variable unit 35 with respect to the optical axis of the reference light. However, the present invention is not limited to this. For example, the optical axis variable unit 35 may be configured as shown in FIGS. In (A), the incident optical axis can be displaced in the parallel direction by moving at least one of the two wedge prisms arranged side by side. In (B), the incident optical axis can be displaced in the parallel direction by simultaneously moving two lenses arranged in the same direction. In (C), the optical axis can be displaced in a parallel direction by moving the mirror. In (D), the optical axis can be displaced in a parallel direction by simultaneously moving two opposing mirrors.

In this embodiment, the optical axis of the reference light is tilted by tilting the wedge prism 104 of the optical axis variable unit 35 with respect to the optical axis of the reference light. However, the present invention is not limited to this. For example, the optical axis variable unit 35 may be configured as shown in FIGS. 7 (A), (B), and (C). (A) tilts the incident optical axis by tilting at least one of the two wedge prisms arranged side by side with respect to the optical axis. (B) tilts the incident optical axis by moving at least one of the two lenses arranged in the direction perpendicular to the optical axis. (C) tilts the optical axis by tilting the mirror. For example, when it is desired to increase or decrease the amount of displacement or inclination in the parallel direction of the optical axis, it may be combined with a beam expander. 6 and 7 has an advantage that correction can be performed with high accuracy as compared with the case where large parts such as an objective lens, a scanner lens, and a relay lens are moved.

As described above, the present embodiment is a two-beam angle multiplexing type hologram recording / reproducing apparatus, which includes a light source unit that emits a light beam and a branch that branches the light beam emitted from the light source unit into signal light and reference light. A first lens unit for irradiating the optical information recording medium with signal light, a second lens unit for incident reference light at substantially the same position as the signal light in the optical information recording medium, and optical information recording An optical path angle varying unit for changing the incident angle of the reference light incident on the medium, and an optical component in the optical path from the light source unit to the first lens unit or the second lens unit are provided. The optical axis variable unit that changes the inclination or the position of the incident light is provided.

Thereby, it is possible to provide a hologram recording / reproducing apparatus or a hologram reproducing apparatus capable of correcting the optical axis inclination and the positional deviation due to the positional deviation and angular deviation of the optical component and capable of performing stable recording / reproducing.

FIG. 8 shows an optical system of the optical pickup device 60 in the hologram recording / reproducing apparatus of the two-beam angle multiplexing system according to this embodiment. This embodiment is characterized in that the reference light correction amount in the optical information recording medium 300 is larger than that in the first embodiment. The present embodiment is different from the first embodiment in that the optical axis variable unit 35 is not provided and the optical component of the reference optical path and the optical axis variable unit 40 are added. Since other than that is the same as that of Example 1, a difference with Example 1 is demonstrated in a present Example. First, the reference optical path will be described.

The reference light reflected from the PBS prism 19 reflects from the mirror 32a, the mirror 32b, the mirror 32c, and the mirror 32d. Here, the mirror 32a, the mirror 32b, the mirror 32c, and the mirror 32d reflect the reference light in the z direction (direction perpendicular to the paper surface of FIG. 8), the y direction, the z direction, and the x direction, respectively. The reference light reflected by the mirror 32d is incident on the mirror 130, the mirror 131, the mirror 33, the half-wave plate 34, the pitch collector 36, the galvano mirror 37, the scanner lens 39, and the optical information recording medium 300. In such an optical system, the present embodiment is characterized in that an optical axis variable unit 40 in which a plurality of optical components are combined as one mechanism unit is disposed. Here, the optical axis variable unit 40 includes a position moving mechanism 41, a position moving mechanism 42, and a position moving mechanism 43 that can move in a predetermined direction. The position moving mechanism 41 is equipped with all parts of the optical path from the mirror 33 to the scanner lens 39, and the position moving mechanism 42 is equipped with the position moving mechanism 41 and the mirror 131. The position moving mechanism 43 includes the position moving mechanism 42, the mirror 130, and the mirror 32d. The means for correcting the relative positional deviation between the signal light and the reference light in the optical information recording medium 300, which is a feature of this embodiment, will be described below.

The position moving mechanism 41, the position moving mechanism 42, and the position moving mechanism 43 of the optical axis variable unit 40 are movable in a moving direction 41D, a moving direction 42D, and a moving direction 43D, respectively. This is because, for example, when the position moving mechanism 41 moves in the y direction different from the moving direction 41D, the position of the reference light incident on the galvano mirror 37 is shifted, and as a result, the optical information recording medium is rotated along with the rotation of the galvano mirror 37. The position of the optical axis of the reference light in 300 changes. In contrast, by moving the position moving mechanism 41 in the same direction as the reference light incident on the mirror 33 as in the present embodiment, the angle of the optical axis of the reference light incident on the optical component from the mirror 33 to the scanner lens 39 is increased. And the position does not go off. On the other hand, since the position moving mechanism 41 moves relative to the objective lens 29, the position of the optical axis of the reference light in the same direction as the moving direction 41D with respect to the irradiation position of the signal light in the optical information recording medium 300. Can move. Further, since there is no angle and position shift of the optical axis incident on the optical component with respect to the movement of the position moving mechanism 41, the irradiation position of the reference light in the optical information recording medium 300 is greatly moved with respect to the first embodiment. It is possible. Furthermore, since the angle and position of the optical axis incident on the optical component does not shift with respect to the movement of the position moving mechanism 41, there is an advantage that no wavefront aberration occurs.

This also applies to the position moving mechanism 42 and the position moving mechanism 43. In FIG. 8, the position moving mechanism 43 seems to include a mirror 32 c and a mirror 32 d, but actually does not include the mirror 32 c, and the position moving mechanism 43 is connected to the mirror 32 d that is the incident end component of the position moving mechanism 43. Since the optical axis is in the Z direction from the mirror 32c, the movable direction of the position moving mechanism 43 is limited to the moving direction 43D which is the Z direction. As described above, in this embodiment, the relative displacement between the signal light and the reference light in the optical information recording medium 300 is corrected by individually moving the position movement mechanism 41, the position movement mechanism 42, and the position movement mechanism 43.

Although there are three position movement mechanisms of the optical axis variable unit 40 of the present embodiment, the number of position movement mechanisms may be reduced by limiting the movement direction.

In addition, since the optical axis variable unit 40 of this embodiment drives a large part, it is not possible to adjust a minute position in the optical information recording medium 300 with respect to the first embodiment. For this reason, the position of the optical axis of the reference light in the optical information recording medium 300 may be finely corrected by combining with the optical axis variable unit 35 and the optical axis variable unit 38 of the first embodiment.

As described above, the present embodiment is a two-beam angle multiplexing type hologram recording / reproducing apparatus, which includes a light source unit that emits a light beam and a branch that branches the light beam emitted from the light source unit into signal light and reference light. A first lens unit for irradiating the optical information recording medium with signal light, a second lens unit for incident reference light at substantially the same position as the signal light in the optical information recording medium, and optical information recording An optical path angle varying unit for changing the incident angle of the reference light incident on the medium, and an optical component in the optical path from the light source unit to the first lens unit or the second lens unit are provided. The second lens unit and the optical path angle variable unit are held in the same casing, and are approximately in the direction of the optical axis incident on the casing. A mechanism is provided that moves the casing in parallel directions.

Further, the second lens unit and the optical path angle variable unit are held in the same casing, and include a mechanism for moving the casing in a direction at least substantially perpendicular to the optical axis direction incident on the casing. To do.

Thus, in this embodiment, the relative position shift between the signal light and the reference light in the optical information recording medium 300 is corrected using the position moving mechanism in the optical axis variable unit 40. This makes it possible to perform stable recording and reproduction even when there are disturbances and changes with time.

FIG. 9 shows an optical system of the optical pickup device 60 in the hologram recording / reproducing apparatus of the two-beam angle multiplexing system according to this embodiment. This embodiment is different from the first embodiment in that an optical axis variable unit 120 and an optical axis variable unit 28 are added to the signal optical path. Since other than that is the same as that of Example 1, a difference with Example 1 is demonstrated in a present Example.

In the first embodiment, the optical axis variable unit 35 is used to shift the position of the optical axis of the reference light in the optical information recording medium 300 with respect to the irradiation position of the signal light and the reference light in the optical information recording medium 300 The relative positional deviation of light was corrected. On the other hand, this embodiment is characterized in that the inclination and position of the signal optical axis are corrected in order to ensure the light quantity and signal quality of the signal light.

In this embodiment, the optical axis variable unit 120 and the optical axis variable on the optical path to the aperture 27 and the objective lens 29 in order to correct the optical axis tilt and the positional deviation of the signal light accompanying the angular deviation and positional deviation of the optical components. The part 28 is arranged. Hereinafter, details regarding the optical axis correction means of the signal light will be described.

First, correction of the optical axis tilt of the signal light by the optical axis variable unit 120 will be described. For example, when the angle or position of the optical component in the common optical path is shifted due to disturbance or change with time, and the optical axis of the signal light is tilted, the irradiation position of the signal light on the opening 27 is shifted. In this case, there is a problem that the amount of light emitted from the opening 27 decreases. Further, since the low frequency component of the signal light is removed by the opening 27, there is a problem that the recording / reproducing performance is deteriorated. Therefore, in this embodiment, the optical axis variable unit 120 that corrects the inclination of the optical axis of the signal light is arranged.

FIG. 10 is a schematic diagram showing the relationship between the optical axis variable portion 120, the lens portion 26A on one side of the relay lens 26, and the opening 27, and the signal light path. In order to simplify the description, components of the optical path from the optical axis variable unit 120 to the lens unit 26A on one side of the relay lens are omitted. FIG. 10A shows an initial state, FIG. 10B shows a state in which the optical axis of the signal light is tilted due to a disturbance or a change with time, and FIG. 10C shows a state in which the optical axis is corrected. ing.

As shown in FIG. 10A, the signal light is incident on the lens portion 26A on one side of the relay lens at a right angle so that the signal light is transmitted through the opening 27, and the signal light is transmitted as shown in FIG. If the light beam enters the lens portion 26A on one side of the relay lens at an angle, the irradiation position of the signal light on the opening 27 is shifted, and the light amount of the signal light is reduced. (C) tilts the wedge prism 106 with respect to the optical axis. The optical axis variable unit 120 of this embodiment includes at least a wedge prism 106 and a rotation mechanism, and the wedge prism 106 is emitted from the wedge prism 106 by being inclined with respect to the optical axis of the reference light by the rotation mechanism. The optical axis of light can be tilted. Thereby, the position of the optical axis of the signal light incident on the opening 27 can be displaced. Thus, in this embodiment, the inclination of the optical axis of the signal light incident on the opening 27 is optimized.

Next, correction of the position of the optical axis of the signal light by the optical axis variable unit 28 will be described. For example, when the position of the spatial light modulator 25 or the relay lens 26 is shifted in the vertical direction with respect to the optical axis of the signal light due to disturbance or changes with time, the position of the optical axis of the signal light incident on the objective lens 29 is shifted. End up. As a result, a part of the signal light is lost due to the objective lens, and there is a problem that normal recording cannot be performed.

Therefore, in this embodiment, the optical axis of the signal light is displaced in the parallel direction by using the optical axis variable unit 28. As for the configuration, like the optical axis variable unit 35 of FIG. 3 of the first embodiment, the optical axis variable unit 28 includes at least a parallel plate and a rotation mechanism. With such a configuration, for example, even when the signal light is displaced in the horizontal direction with respect to the optical axis due to disturbance or changes with time, the objective lens can be obtained by tilting the parallel plate of the optical axis variable unit 28 with respect to the optical axis. The position of the optical axis incident on 29 can be corrected. Thereby, in this embodiment, the position of the optical axis of the signal light incident on the objective lens 29 is optimized. Note that the optical axis variable unit 28 can also adjust the position of the reproduction signal light on the image sensor 52 during reproduction.

In the present embodiment, the optical axis variable unit 28 displaces the optical axis of the signal light in the parallel direction, but is not limited thereto. For example, the inclination of the signal light may be corrected by adding a wedge prism and a rotation mechanism to the optical axis variable unit 28. In this way, for example, the angular deviation of the image sensor 52 can be corrected during reproduction.

In this embodiment, the optical axis variable unit 120 is used to correct the tilt of the optical axis of the incident light of the aperture 27. However, the spatial light modulator 25 may be tilted as the optical axis variable unit. In this embodiment, the optical axis variable unit 28 is used to displace the signal light in the direction parallel to the optical axis by correcting the incident light of the objective lens 29. For example, the two-dimensional data of the spatial light modulator 25 is used. The display, which is the output of, may be moved. By doing in this way, it can be set as a simple structure. The present embodiment is characterized in that the optical axis of the signal light is displaced or tilted in a parallel direction with respect to disturbances and changes with time with respect to the optical component. Therefore, the optical axis is made parallel using the display of the spatial light modulator 25. Displacement in the direction is also a feature of this embodiment.

As described above, in this embodiment, the amount of signal light transmitted through the opening 27 and the recording / reproducing performance are secured by tilting the optical axis of the signal light. Also, stable recording can be performed by displacing the optical axis of the signal light in the parallel direction and correcting the position of the optical axis incident on the objective lens. This makes it possible to perform stable recording and reproduction even when there are disturbances and changes with time.

FIG. 11 shows an optical system of the optical pickup device 60 in the hologram recording / reproducing apparatus of the two-beam angle multiplexing system according to this embodiment. This embodiment differs from Embodiment 1 in that an optical axis variable unit 12 is added to the common optical path. Since other than that is the same as that of Example 1, a difference with Example 1 is demonstrated in a present Example.

In Example 1, the relative positional deviation between the signal light and the reference light in the optical information recording medium 300 was corrected. In this embodiment, in addition to that, the tilt of the optical axis of the light beam incident on the pinhole 14 is corrected in order to ensure recording / reproducing performance and recording / reproducing speed.

For example, when the optical axis of the optical beam incident on the relay lens 13 is tilted due to an angular deviation or a positional deviation of the optical components in the common optical path due to disturbance or a change with time, the pinhole 14 is in contrast to the hole of the pinhole 14. The irradiation position of the upper light beam is shifted. This is the same reason as FIG. 10 of the third embodiment. The pinhole 14 is used together with the relay lens 13 to remove unnecessary frequency component fluctuations from the intensity distribution of the light beam. The hole diameter of the pinhole 14 depends on the wavelength of the beam, the effective diameter of the beam, and the focal length of the relay lens 13. For example, when the wavelength is 405 nm, the effective diameter is 4 mm, and the relay lens focal length is 10 mm, the intensity distribution In order to remove the predetermined frequency component, the hole diameter of the pinhole 14 is several μm. In this case, the amount of light emitted from the pinhole 14 is significantly reduced only by tilting the optical axis of the light beam incident on the relay lens 13 by several tens of millimeters. As a result, the light amounts of the signal light and the reference light are reduced, resulting in a problem that a desired recording / reproducing speed cannot be obtained. In this case, a frequency component that does not require an intensity distribution passes through the pinhole 14 and is recorded as a hologram on the optical information recording medium 300, which causes a problem that the recording / reproducing performance deteriorates.

For this reason, in this embodiment, the optical axis variable portion 12 is used to correct the inclination of the optical axis of the incident light to the pinhole 14. Regarding the configuration, like the optical axis variable unit 120 of FIG. 10 of the third embodiment, the optical axis variable unit 12 includes at least a wedge prism and a rotation mechanism. Thereby, in the present embodiment, the inclination of the optical axis of the light incident on the pinhole 14 is optimized.

As described above, in this embodiment, the optical axis variable portion 12 is used to incline the optical axis of incident light to the relay lens 13 and the pinhole 14, thereby ensuring the recording / reproducing performance and the recording / reproducing speed. This makes it possible to perform stable recording and reproduction even when there are disturbances and changes with time.

FIG. 12 shows an optical system of the optical pickup device 60 in the hologram recording / reproducing apparatus of the two-beam angle multiplexing system according to the present embodiment. The present embodiment is different from the first embodiment in that an optical axis variable unit 15 is added to the common optical path. Since other than that is the same as that of Example 1, a difference with Example 1 is demonstrated in a present Example.

In Example 1, the relative positional deviation between the signal light and the reference light in the optical information recording medium 300 was corrected. In this embodiment, in addition to that, correction of wavefront aberration and correction of intensity distribution are performed.

The intensity distribution conversion lens 16 of this embodiment is a lens that makes the intensity distribution described in Japanese Patent No. 3614294 uniform, for example. In this embodiment, a uniform intensity distribution is obtained by using the intensity distribution conversion lens 16. However, the intensity distribution conversion lens 16 has problems of deterioration of uniformity of the intensity distribution and generation of wavefront aberration with respect to the positional deviation and inclination of the optical axis of the light incident on the intensity distribution conversion lens 16. The intensity distribution conversion lens 16 makes the intensity distribution uniform by spreading the light intensity of the central part to the peripheral part and collecting the light intensity of the peripheral part toward the central part with respect to the intensity distribution of the Gaussian distribution emitted from the laser. ing. For this reason, if the position of the optical axis of the light beam incident on the intensity distribution conversion lens 16 is shifted, the uniformity of the intensity distribution deteriorates accordingly. Further, in order to make the intensity distribution uniform, the intensity distribution conversion lens 16 has a shape in which the inclination of the lens surface of the central portion and that of the peripheral portion are different, and the optical axis of the light beam incident on the intensity distribution conversion lens 16 is inclined. Then, wavefront aberration mainly composed of coma aberration occurs.

For this reason, in this embodiment, the optical axis variable section 15 having the function of displacing the optical axis in the parallel direction and the function of tilting is arranged. FIG. 13 shows the optical axis variable unit 15 of the present embodiment. The optical axis variable unit 15 includes a wedge prism 103 and at least a translation mechanism and a rotation mechanism. FIG. 13A shows a case where the wedge prism 103 is moved in a direction perpendicular to the optical axis by the translation mechanism, and FIG. 13B shows a case where the wedge prism 103 is tilted with respect to the optical axis by the rotation mechanism. The solid lines in (A) and (B) indicate the initial state, and the dotted line indicates the wedge prism 103 and the optical axis of the light beam when the wedge prism 103 is displaced or tilted.

The optical axis variable unit 15 of the present embodiment can displace the incident optical axis in the parallel direction by moving the wedge prism 103 in a direction substantially perpendicular to the optical axis as shown in FIG. Further, as shown in (B), by tilting the wedge prism 103 with respect to the optical axis, the optical axis emitted from the wedge prism 103 can be tilted.

In this embodiment, the optical axis variable unit 15 is used to correct the positional deviation and the inclination of the optical axis of the incident light to the intensity distribution conversion lens 16 caused by the disturbance and change with time of the optical component. Thus, in this embodiment, the position and inclination of the optical axis of the light beam incident on the wedge prism 103 are optimized.

The wedge prism 103 of this embodiment has a small amount of displacement in the direction parallel to the optical axis with respect to the amount of movement. Further, the wedge prism 103 has a small change amount of the inclination of the optical axis with respect to the inclination amount. For this reason, it can correct | amend with high precision even if it uses cheap drive components, such as a stepping motor.

In this embodiment, the displacement and inclination of the optical axis are corrected only by the wedge prism 103, but the present invention is not limited to this. For example, two wedge prisms with optimized optical axis displacement and tilt may be arranged. Moreover, you may combine the structure shown in FIG. 6, FIG. The intensity distribution conversion lens 16 is similar to the present embodiment by using an optical axis variable unit as long as the intensity distribution is converted using the same method even if the emitted light is not in a top flat shape. The effect is obtained. In this embodiment, the intensity distribution conversion lens 16 is a lens, but may be a diffraction element or the like.

As described above, in this embodiment, the optical axis of the light beam transmitted through the intensity distribution conversion lens 16 is displaced by displacing the optical axis of the light incident on the intensity distribution conversion lens 16 in the parallel direction using the optical axis variable unit 15. The distribution is made uniform. Further, the occurrence of wavefront aberration is suppressed by tilting the optical axis of the incident light to the intensity distribution conversion lens 16 using the optical axis variable unit 15. This makes it possible to perform stable recording and reproduction even when there are disturbances and changes with time.

In this embodiment, a control method for driving the rotation mechanism and the translation mechanism of the optical axis variable unit will be described. FIG. 14 shows an optical system of the optical pickup device 60 in the hologram recording / reproducing apparatus of the two-beam angle multiplexing system according to this embodiment. In FIG. 14, the same reference numerals as those of the optical components shown in the respective embodiments have the same functions as those of the optical components of the respective embodiments.
Hereinafter, a control method for driving the rotation mechanism and the translation mechanism of each optical axis variable unit will be described. In this embodiment, at the time of recording / reproducing, the reference light reflected from the PBS prism 19 is converted into P-polarized light by the polarization variable element 30 and passes through the PBS prism 31. As a result, recording / reproduction similar to that in the first embodiment can be performed.

First, a control method for driving the rotation mechanism of the optical axis variable unit 12 will be described. First, in FIG. 14, the polarization variable element 30 is controlled so that the outgoing polarized light from the polarization variable element 30 becomes S-polarized light. As a result, the S-polarized light transmitted through the polarization variable element 30 is reflected by the PBS prism 31 and is condensed on the image sensor 601 by the detection lens 600. Next, the rotation mechanism of the optical axis variable unit 12 is driven so that the signal intensity of the image sensor 601 increases, and the optical axis of the light beam is tilted. Then, when the signal intensity of the image sensor 601 becomes maximum, the rotation mechanism of the optical axis variable unit 12 is stopped. The present embodiment is characterized in that the rotation mechanism of the optical axis variable unit 12 is driven using the amount of light emitted from the pinhole 14 as a detection signal. In this way, the light beam can be controlled to pass through the center of the pinhole 14.
Next, a control method for driving the rotation mechanism and the translation mechanism of the optical axis variable unit 15 will be described. First, a control method for driving the rotation mechanism of the optical axis variable unit 15 will be described.
In FIG. 14, the light beam is incident on the image sensor 601 in the same manner as the control method of the optical axis variable unit 12. Then, the optical axis of the incident light to the intensity distribution conversion lens 16 is tilted using the rotation mechanism of the optical axis variable unit 15 so that the spot on the image sensor 601 is minimized. FIG. 15 shows the inclination of the optical axis of the light incident on the intensity distribution conversion lens 16 on the upper stage, and shows the relationship of the spots on the image sensor 601 at that time on the lower stage. (A), (B), and (C) are different in the inclination of the optical axis of the light beam incident on the intensity distribution conversion lens 16, and (B) is the optical axis of the light beam incident on the intensity distribution conversion lens 16. (A) and (C) show the state in which the optical axis of the incident light beam is tilted. As described above, the intensity distribution conversion lens 16 generates wavefront aberration mainly composed of coma aberration when the optical axis of the light beam incident on the intensity distribution conversion lens 16 is tilted. Thereby, the spot on the image sensor 601 is distorted. Using this characteristic, in this embodiment, the inclination of the light beam incident on the intensity distribution conversion lens 16 is corrected by inclining the optical axis using the optical axis variable unit 15 so that the spot on the image sensor is minimized. Thereby, the generated wavefront aberration can be reduced.
Next, a control method for driving the translation mechanism of the optical axis variable unit 15 will be described. First, in FIG. 14, the polarization variable element 20 is controlled so that the outgoing polarized light from the polarization variable element 20 becomes S-polarized light. As a result, the S-polarized light that has passed through the polarization variable element 20 passes through the beam expander 21, the phase mask 22, and the relay lens 23, is reflected by the PBS prism 24, and enters the imaging element 52. Then, an image from the image sensor 52 is detected. At this time, when the intensity distribution of the detected image is asymmetric, the translation mechanism of the optical axis variable unit 15 is driven, and the optical axis is changed to the optical axis so that the intensity distribution on the image sensor 52 is substantially symmetric. Displace in the parallel direction. Thereby, a substantially uniform intensity distribution can be obtained. As described above, this embodiment is characterized in that the coma aberration of the light beam emitted from the intensity distribution conversion lens 16 is observed and the rotation mechanism of the optical axis variable unit 15 is driven. Further, the translation mechanism is driven by detecting the intensity distribution of the light beam emitted from the intensity distribution conversion lens 16. By performing the above correction, the best wavefront aberration and intensity distribution for hologram recording / reproduction can be obtained.

Next, a control method for driving the rotation mechanism of the optical axis variable unit 120 will be described. First, in FIG. 14, the polarization variable element 18 and the polarization variable element 20 are controlled so that only the signal light enters the optical information recording medium 300. At this time, the signal light passes through the optical information recording medium 300, and the signal light enters the detector 606 through the collimating lens 604 and the detection lens 605. In the present embodiment, the rotation mechanism of the optical axis variable unit 120 is driven so that the detection signal of the detector 606 increases, and the optical axis of the signal light is tilted. Then, when the signal intensity of the detector 606 reaches the maximum, the rotation mechanism of the optical axis variable unit 120 is stopped. The present embodiment is characterized in that the rotation mechanism of the optical axis variable unit 120 is driven using the amount of light emitted from the opening 27 as a detection signal. In this way, the signal light can be controlled to enter the center of the opening 27.

Next, a control method for driving the translation mechanism of the optical axis variable unit 28 will be described. First, in FIG. 14, the translation mechanism of the optical axis variable unit 28 is driven to displace the optical axis of the signal light in a direction parallel to the optical axis. When the optical axis of the signal light is displaced, the signal light is lost by the objective lens 29, so that the amount of light is reduced. This is the first position, and then the optical axis is displaced to the opposite side. Then, the position where the amount of light again decreases is set as the second position. In this embodiment, the translation mechanism of the optical axis variable unit 28 is driven so that the reference light is arranged at a substantially intermediate position between the first position and the second position. In this way, the signal light can be controlled to pass through the center of the objective lens 29.

Finally, a control method for driving the rotation mechanism of the optical axis variable unit 35 will be described. First, the optical information recording medium 300 is changed to an adjustment medium 301 having an opening 302. At this time, it is desirable that the optical information recording medium 300 and the adjustment medium 301 have the same thickness and the same refractive index. FIG. 16 shows the adjustment medium 301, where the upper part shows a plan view and the lower part shows a cross-sectional view. In FIG. 16, the opening 302 of the adjustment medium 301 includes a light shielding region 302 </ b> A and a light shielding region 302 </ b> B, and the light beam incident on the light shielding region is not transmitted through the adjustment medium 301. Further, the light shielding region 302A is disposed inside the light shielding region 302B, and is characterized by a substantially trapezoidal shape. In addition, the dashed-dotted line and the dashed-two dotted line in a figure have each shown the signal light and the reference light. Therefore, the light shielding region 302A is a region that shields the signal light, and the light shielding region 302B is a region that shields the peripheral portion of the reference light. Using such an adjustment medium 301, the relative positions of the signal light and the reference light in the optical information recording medium 300 are corrected.

In FIG. 14, after changing to the adjustment medium 301, the polarization variable element 18 and the polarization variable element 20 are controlled so that only the signal light enters the adjustment medium 301. At this time, if the signal light is incident outside the light shielding region 302A and the light shielding region 302B, the signal light is transmitted through the adjustment medium 301 and enters the detector 606 through the collimator lens 604 and the detection lens 605. In the present embodiment, the position of the adjustment medium 301 is adjusted so that the signal light is irradiated into the light shielding region 302A and the signal intensity of the detector 606 is minimized. By doing this, the light shielding region 302A can be arranged at a position where the signal light converges in the adjustment medium 301. Next, the polarization variable element 18 and the polarization variable element 30 are controlled so that only the reference light enters the adjustment medium 301. Here, the galvanometer mirror 37 and the galvanometer mirror 51 are controlled to have a predetermined angle. By doing in this way, the reference light incident on the adjustment medium 301 other than the light shielding region 302A and the light shielding region 302B is used for the quarter wavelength plate 50, the galvanometer mirror 51, the quarter wavelength plate 50, the adjustment medium 301, The light enters the PBS prism 31 through the scanner lens 39, the galvanometer mirror 37, the pitch collector 36, the optical axis variable unit 35, the half-wave plate 34, the mirror 33, and the mirror 32. The reference light that has entered the PBS prism 31 has been converted to S-polarized light by passing through the quarter-wave plate 50 twice, and therefore reflects the PBS prism 31 and enters the detector 602. In this embodiment, the rotation mechanism of the optical axis variable unit 35 is driven so that the signal intensity of the detector 602 is maximized, and the position of the optical axis of the reference light in the optical information recording medium 300 is displaced. Then, when the signal intensity of the detector 602 becomes maximum, the rotation mechanism of the optical axis variable unit 35 is stopped.

By performing this series of steps, the position of the reference light on the adjustment medium 301 can be matched with the transmission region inside the light shielding region 302B. Finally, when the adjustment medium 301 is changed to the optical information recording medium 300, the correction is completed.

Thus, in this embodiment, the position of the signal light and the reference light in the medium is adjusted with high accuracy by using the adjusting medium 301 having an opening.

By driving the rotation mechanism and translation mechanism of each optical axis variable unit using the control method as described above, there is a case where the optical axis is tilted and the position is shifted due to disturbance or change over time with respect to the optical component. In addition, stable recording and reproduction can be performed.

In addition, since the present embodiment is characterized by including an optical axis variable unit that arbitrarily changes the optical axis, the target to be corrected is not limited. For example, the optical axis of a light beam incident on a pinhole, an aperture, a relay lens, or the like arranged at a position different from the present embodiment may be corrected. Further, the correction target is not limited to the correction target of the present embodiment, and the correction target may be increased or decreased. In the present embodiment, the description has been made by correcting the relative positions of the signal light and the reference light in the optical information recording medium 300 of the first embodiment, but the correcting means of the second embodiment may be used.

In this embodiment, the intensity distribution conversion lens 16 is described as one. However, in order to make the signal light and the reference light have an optimum intensity distribution, an intensity distribution conversion lens may be arranged in each optical path. In this case, an optical axis variable unit corresponding to each may be arranged.

The adjustment medium 301 of this embodiment may be in the hologram recording / reproducing apparatus or in an apparatus for storing the hologram recording / reproducing apparatus. In this embodiment, the spot image is detected by the detection lens 600 and the image sensor 601. However, a wavefront sensor or the like that measures the wavefront may be used. Furthermore, the shape of the light shielding region 302A of the adjustment medium 301 is substantially trapezoidal because the coma aberration of the signal light has an effect. However, the same detection can be performed even if it is other than the trapezoid.

The optical axis tilt and misalignment correction of this embodiment can be used for initial shipment of the hologram recording / reproducing apparatus, maintenance after shipment, and repair in case of abnormality. In the present embodiment, the imaging element 601 and the imaging element 52 are detected using the polarization variable element 30 and the polarization variable element 20 in order to detect the tilt and the positional deviation of the optical axis of the light incident on the pinhole 14 and the intensity distribution conversion lens 16. However, the polarization may be converted in advance so that a slight light beam is incident on the image sensor 601 and the image sensor 52 using, for example, a wavelength plate. Further, the leakage light of the PBS prism 31 and the PBS prism 24 may be detected by the image sensor 601 and the image sensor 52 without intentionally converting the polarization. In this embodiment, the image sensor 601 is arranged in the reference optical path, but it may be in the signal optical path or in the common optical path as long as it is after the pinhole 14 or the intensity distribution conversion lens 16. Also good. Furthermore, in order to drive the translation mechanism of the optical axis variable unit 15, the intensity distribution is detected from the image sensor 52. For example, a lens or an element that extends the optical path is taken in and out of the optical path to the image sensor 601. The intensity distribution may be detected from the image sensor 601 by bringing the light beam on the screen 601 into a defocused state.

The detection signal from the detector 602 is used to drive the rotation mechanism of the optical axis variable unit 35. However, the configuration is not limited to this configuration as long as the transmitted light of the adjustment medium 301 can be detected. For example, a detector may be disposed between the adjustment medium 301 and the quarter wavelength plate 50 when the adjustment medium 301 is inserted. A detector may be attached to the adjustment medium 301. By doing in this way, there exists an advantage which can implement | achieve size reduction and cost reduction rather than the structure of a present Example. Then, the reference light transmitted through the galvanometer mirror 51 may be detected.

In this embodiment, the adjustment medium 301 is used. For example, as shown in FIG. 17, the adjustment medium 303 and the image sensor 607 in which the protective layer and the medium are half the thickness of the optical information recording medium 300. May be used to detect the relative position of the signal light and the reference light in the optical information recording medium 300.

In this case, first, the image sensor 607 is disposed between the adjustment medium 303 and the adjustment medium 303 and the quarter-wave plate 50. Note that the adjustment medium 303 and the image sensor 607 may be in contact with each other. Then, the polarization variable element 18 and the polarization variable element 20 are controlled so that only the signal light enters the adjustment medium 303. Thereafter, the image sensor 607 is driven in the optical axis direction of the objective lens 29 so that the signal light becomes the smallest spot, and the position is determined. By doing in this way, the light-receiving surface of the image pick-up element 607 can be matched with the position where signal light converges. Next, the polarization variable element 18 and the polarization variable element 30 are controlled such that only the reference light enters the adjustment medium 303. Here, the rotation mechanism of the optical axis variable unit 35 is driven, and the optical axis is displaced on the image sensor 607 so that the center of the reference light substantially coincides with the convergence position of the signal light. Finally, if the adjustment medium 303 is changed to the optical information recording medium 300, the correction is completed.

Thereby, the relative positional deviation between the signal light and the reference light in the optical information recording medium 300 can be corrected. By doing in this way, there exists an advantage which can implement | achieve size reduction and cost reduction. Further, the adjustment medium 303 may not be provided as compared with FIG. In this case, the distance between the signal light and the reference light at the position where the signal light converges on the image sensor 607 is calculated in advance, and the distance between the signal light and the reference light on the image sensor 607 is adjusted according to the amount. You may do it.

FIG. 18 shows an optical system of the optical pickup device 60 in the hologram recording / reproducing apparatus of the two-beam angle multiplexing system according to the present embodiment. The present embodiment is different from the sixth embodiment in that an optical axis variable unit 38 is added to the reference optical path. Since other than that is the same as that of Example 6, a difference with Example 6 is demonstrated in a present Example. In this embodiment, a control method for driving the rotation mechanisms of the optical axis variable unit 35 and the optical axis variable unit 38 will be described.

18, first, the optical information recording medium 300 is changed to the adjustment medium 301, and the position of the adjustment medium 301 is determined using the signal light in the same manner as in the sixth embodiment. Next, the polarization variable element 18 and the polarization variable element 30 are controlled so that only the reference light enters the adjustment medium 301. Here, the galvanometer mirror 37 and the galvanometer mirror 51 are controlled to have a predetermined angle. By doing so, the reference light is incident on the image sensor 603 as in the first embodiment. Then, the rotation mechanism of the optical axis variable unit 38 is driven so that the signal intensity of the image sensor 603 is maximized, and the irradiation position of the reference light on the adjustment medium 301 is determined.

Next, the angle between the galvanometer mirror 37 and the galvanometer mirror 51 is changed. At this time, if the light beam on the image sensor 603 changes symmetrically, the optical axis variable unit 35 and the optical axis variable unit 38 are optimal. If it is not centrally symmetric at this time, the following steps are repeated. First, the galvanometer mirror 37 and the galvanometer mirror 51 are controlled to have a predetermined angle. Then, after driving the rotation mechanism of the optical axis variable unit 35 and changing the position of the optical axis of the reference light incident on the adjustment medium 301, the optical axis variable unit so that the signal intensity of the image sensor 603 becomes maximum. The rotation mechanism 38 is driven to determine the position of the optical axis of the reference light irradiated on the adjustment medium 301. Here, the correction amount and direction of the rotation mechanism of the optical axis variable unit 35 can be calculated from the change amount and direction of the light beam on the image sensor 603 corresponding to the angle between the galvanometer mirror 37 and the galvanometer mirror 51.

Thereafter, the angle of the galvanometer mirror 37 and the galvanometer mirror 51 is changed, and the change of the light beam on the image sensor 603 is confirmed. At this time, if the light beam on the image sensor 603 changes symmetrically, the correction is completed. If it is not centrally symmetric, correction is performed again. By repeating this, the optical axis variable unit 35 and the optical axis variable unit 38 can be optimized.

Hereinafter, the reason why the positional deviation of the optical axis of the reference light in the adjustment medium 301 can be confirmed using the reference light on the image sensor 603 will be described.

FIG. 19 shows the position of the light shielding region 302B of the opening 302 in the adjustment medium 301 with respect to the reference light (left side view) and the size of the reference light on the image sensor 603 at that time (right side view). Here, FIGS. 19A, 19B1 and 19B2 are different in the angle of the optical axis of the reference light incident on the adjustment medium 301. FIG. Further, (B1) and (B2) are different in the position of the optical axis of the reference light incident on the light shielding region 302B. Reference light 801, reference light 803, and reference light 805 indicate reference light from the galvano mirror 37 side, and reference light 802, reference light 804, and reference light 806 indicate reference light from the galvano mirror 51 side. Show. Further, the hatched portion in the figure indicates the reference light on the image sensor 603. For simplicity of explanation, the light shielding region 302A of the opening 302 of the adjustment medium 301 is not considered. For the same reason, the light shielding region 302B is rectangular.

In this embodiment, the rotation mechanism of the optical axis variable unit 38 is driven to determine the position of the optical axis of the reference light incident on the adjustment medium 301, and then the angle between the galvano mirror 37 and the galvano mirror 51 is changed. Since the reference light is incident on the adjustment medium 301 at an angle, the size of the reference light in the adjustment medium 301 changes. That is, when the reference light is irradiated onto the opening 302 in the adjustment medium 301, the size of the light-shielding region 302B with respect to the reference light changes according to the incident angle of the reference light, and thus enters the image sensor 603. The size of the reference light changes.

Here, for example, when the position of the optical axis of the reference light on the adjustment medium 301 is not shifted as shown in (B1) with respect to FIG. 19A, the size of the reference light with respect to the center of the light shielding region 302B. Changes symmetrically, the reference light limited by the light shielding region 302B changes symmetrically with respect to the central axis 800 like the reference light 808. On the other hand, when the position of the optical axis of the reference light is shifted as shown in (B2) with respect to FIG. 19A, the light beam limited by the light shielding region 302B is relative to the central axis 800 like the reference light 809. Changes asymmetrically. By detecting this, it is possible to detect a change in the position of the optical axis of the reference light in the adjustment medium 301 accompanying the rotation of the galvanometer mirror 37.

By driving the rotation mechanism of each optical axis variable unit using the control method as described above, the optical component is stable even when there is a tilt or position shift of the optical axis due to disturbance or change over time. Recording and reproduction can be performed. In addition, the present embodiment can correct the optical component to an optimum state even if a large angular shift or positional shift of the optical component occurs with respect to the sixth embodiment. In this embodiment, the image sensor 603 is used. However, an element that measures the positional deviation of the light beam, such as a position detector, may be used.

In this embodiment, the adjustment medium 301 is used. However, for example, as shown in FIG. 17, the protective layer and the medium are half the thickness of the optical information recording medium 300 and the adjustment medium 303 is imaged. The relative position between the signal light and the reference light in the optical information recording medium 300 may be detected using the element 607.

In this case, first, the image sensor 607 is disposed between the adjustment medium 303 and the adjustment medium 303 and the quarter-wave plate 50. Then, the polarization variable element 18 and the polarization variable element 20 are controlled so that only the signal light enters the adjustment medium 301. Thereafter, the image sensor 607 is driven in the optical axis direction of the objective lens 29 so that the signal light becomes the smallest spot. Next, the polarization variable element 18 and the polarization variable element 30 are controlled so that only the reference light enters the adjustment medium 301. Here, the galvanometer mirror 37 is driven, and the optical axis is displaced using the optical axis variable unit 35 so that the positional deviation associated with the angle of the galvanometer mirror 37 on the image sensor 607 is reduced. Thereafter, the optical axis is displaced using the optical axis variable unit 38 so that the irradiation position of the signal light coincides with the center of the reference light. Finally, if the adjustment medium 303 is changed to the optical information recording medium 300, the correction is completed.

Thereby, the relative positional deviation between the signal light and the reference light in the optical information recording medium 300 can be corrected. By doing in this way, there exists an advantage which can implement | achieve size reduction and cost reduction rather than the structure of a present Example. Further, there is an advantage that correction can be performed at a higher speed than in the present embodiment.

FIG. 20 shows a correction flow of the hologram recording / reproducing apparatus of the two-beam angle multiplexing system according to the present embodiment. In addition, a present Example has shown the adjustment flow in the case of the structure of FIG.

As shown in FIG. 20, the correction flow includes correction of the inclination of the optical axis of the incident light to the pinhole 14 by the optical axis variable unit 12 (S 1), and incident light to the intensity distribution conversion lens 16 by the optical axis variable unit 15. Correction of the optical axis inclination and position (S2), correction of the optical axis inclination of the incident light to the aperture 27 by the optical axis variable unit 120 (S3), and correction of the incident light to the objective lens 29 by the optical axis variable unit 28 Correction of the position of the optical axis (S4) and correction of the relative position of the signal light and the reference light in the optical information recording medium 300 by the optical axis variable unit 35 are performed in this order (S5). The present correction flow is characterized in that the signal light and the reference light are corrected at least after the common optical path is corrected. Further, each optical path in the common optical path, the signal optical path, and the reference optical path is characterized in that correction is performed in order from the light source.

For example, if the inclination of the optical axis of the incident light to the pinhole 14 is corrected after the inclination and position of the optical axis of the incident light to the intensity distribution conversion lens 16 are corrected, Although it is inclined, the optical axis incident on the intensity distribution conversion lens 16 is inclined, which causes a problem that wavefront aberration occurs. On the other hand, if the inclination and the position of the optical axis of the incident light to the intensity distribution conversion lens 16 are corrected after the correction of the inclination of the optical axis of the incident light to the pinhole 14 as in this embodiment, the pinhole 14, Both the intensity distribution conversion lenses 16 have an optimum optical axis inclination. By performing correction in this way, the light amount, intensity distribution, and wavefront aberration can be optimized.

By performing the correction flow as described above, stable recording / reproduction can be performed even when the optical component is tilted or displaced due to a disturbance or change with time.
Although a plurality of correction targets are shown in the present embodiment, it is not always necessary to perform all corrections, and the correction targets may be increased or decreased. The feature of the present embodiment is that the signal light and the reference light are corrected at least after the correction of the common optical path, and the correction is performed in the order closer to the light source in each of the common optical path, the signal optical path, and the reference optical path. Therefore, it is necessary to change the adjustment flow according to the configuration of the optical system. For example, when the intensity distribution conversion lens 16 is arranged closer to the light source than the pinhole 14, the intensity distribution conversion lens is corrected first. Note that either the signal light or the reference light may be corrected first.

FIG. 21 shows an adjustment flow of the hologram recording / reproducing apparatus of the two-beam angle multiplexing system according to the present embodiment. The eighth embodiment has been described on the assumption that all adjustments are performed. However, an adjustment flow for performing stable recording / reproduction is provided even when a disturbance or a change with time occurs during recording / reproduction. In addition, a present Example has shown the adjustment flow in the case of the structure of FIG. In this embodiment, in FIG. 14, it is assumed that a part of the reference light beam is reflected by the PBS prism 31 and is incident on the detector 601.
FIG. 21 shows an adjustment flow in the case where there is a disturbance during recording / reproducing operation and an angular deviation and a positional deviation of the optical components in the common optical path due to a change with time.
In FIG. 21, first, recording / reproduction is started, and after recording / reproducing a predetermined amount of data (Sa1), the output signal intensity of the detector 601 is confirmed (Sa2). At this time, if the output signal intensity of the detector 601 is greater than or equal to a predetermined amount, a predetermined amount of data is recorded and reproduced (Sa3). On the other hand, when the output signal intensity of the light receiving unit 601 becomes a predetermined amount or less, recording / reproduction is temporarily interrupted (Sa5), and the optical axis of the incident light to the pinhole 14 by the optical axis variable unit 12 After correcting the inclination (Sa6), recording / reproduction is resumed, and recording / reproduction of a predetermined area is performed (Sa3). At this time, if the recording / reproduction is not completed, a predetermined amount of data is again recorded / reproduced (Sa1), the output signal intensity of the detector 601 is confirmed (Sa2), and the recording / reproduction is continued.

The present embodiment is characterized in that a change in the intensity of the light beam accompanying the angular deviation and positional deviation of the optical component during recording / reproduction is confirmed by the detector 601, and the necessity of correction is determined using the signal. In the present embodiment, when the recording / reproduction is interrupted (Sa5), only the optical axis inclination correction (Sa6) of the incident light to the pinhole 14 is performed by the optical axis variable unit 12, but this is not limitative. . For example, the correction may be performed by combining correction of the inclination and position of the optical axis of the incident light to the intensity distribution conversion lens 16 by the optical axis variable unit 15. Further, in this embodiment, when the output signal intensity of the light receiving unit 601 has become a predetermined amount or less, the recording / reproduction is temporarily interrupted (Sa5), but the output signal intensity of the light receiving unit 601 is not interrupted. The optical axis variable unit 12 may be finely adjusted so as to increase.
Further, it is a feature of this embodiment that a change in the intensity of the light beam is detected by a detector to determine the necessity for correction. For this reason, the necessity for correction of the optical axis variable unit may be confirmed using signals from other detectors. For example, using the output signal of the detector 606 in FIG. 14, the optical axis variable unit 120 corrects the inclination of the optical axis of the incident light to the aperture 27, and the optical axis variable unit 28 sets the optical axis of the incident light to the objective lens 29. The position may be corrected.
Furthermore, in the present embodiment, after recording and reproducing (Sa3) a predetermined amount of data, the output signal intensity of the detector 601 is confirmed (Sa2). However, the present invention is not limited to this. For example, the output signal intensity of the detector 601 may be constantly checked, and the correction by the optical axis variable unit may be performed when the output signal intensity of the light receiving unit 601 becomes a predetermined amount or less.

The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. Further, although each embodiment has been described with respect to the hologram recording / reproducing apparatus, it may be a hologram recording apparatus or a hologram reproducing apparatus.

10: light source, 11: collimating lens, 12, optical axis variable unit, 13: relay lens, 14: pinhole, 15: optical axis variable unit, 16: intensity distribution conversion lens, 17: shutter, 18: polarization variable element, 19: PBS prism, 20: polarization variable element, 21: beam expander, 22: phase mask, 23: relay lens, 24: PBS prism, 25: spatial light modulator (SLM), 26: relay lens, 27: aperture 28: Optical axis variable part, 29: Objective lens, 30: Polarization variable element, 31: PBS prism, 32: Mirror, 33: Mirror, 34: 1/2 wavelength plate, 35: Optical axis variable part, 36: Pitch Collector: 37: Galvano mirror, 38: Optical axis variable unit, 39: Scanner lens, 40: Optical axis variable unit, 41: Position moving mechanism, 42: Position moving mechanism, 43: Position moving mechanism 50: 1/4 wavelength plate, 51: Galvano mirror, 52: Imaging element, 60: Optical pickup device, 70: Optical information recording medium driving element, 82: Light source driving circuit, 85: Signal processing circuit, 86: Signal generation circuit , 87: shutter control circuit, 89: controller, 120: optical axis variable unit, 300: optical information recording medium, 301, 303: adjustment medium, 302: aperture, 512: phase conjugate optical system, 513: optical information recording Medium Cure optical system, 600: detection lens, 601: imaging device, 602: detector, 603: imaging device, 604: collimating lens, 605: detection lens, 606: detector

Claims

A hologram recording / reproducing apparatus of a two-beam angle multiplexing system,
A light source that emits a light beam;
A branching section for branching the light beam emitted from the light source section into signal light and reference light;
A first lens unit for irradiating the optical information recording medium with the signal light;
A second lens unit for injecting the reference light at substantially the same position as the signal light in the optical information recording medium;
An optical path angle variable unit for changing an incident angle of the reference light incident on the optical information recording medium;
An optical component in an optical path from the light source unit to the first lens unit or the second lens unit;
With
A hologram recording / reproducing apparatus comprising an optical axis variable unit that changes the inclination or position of incident light on the optical component.
The hologram recording / reproducing apparatus according to claim 1,
The branch is a PBS prism;
The first lens unit is an objective lens,
The second lens unit is a scanner lens;
The optical path angle variable unit is a galvanometer mirror,
And a hologram recording / reproducing apparatus.
The hologram recording / reproducing apparatus according to claim 1,
In the optical path from the light source part to the first lens part or the second lens part, a pinhole is provided,
The hologram recording / reproducing apparatus, wherein the optical axis variable unit tilts an optical axis incident on the pinhole.
The hologram recording / reproducing apparatus according to claim 1,
In the optical path from the light source unit to the first lens unit or the second lens unit, an intensity distribution conversion unit that converts an intensity distribution of a substantially Gaussian distribution into an intensity distribution of a substantially top hat shape is provided.
The hologram recording / reproducing apparatus, wherein the optical axis variable unit tilts at least an optical axis of a light beam incident on the intensity distribution conversion unit.
The hologram recording / reproducing apparatus according to claim 1,
The hologram recording / reproducing apparatus, wherein the optical axis variable unit changes a position of an optical axis of a light beam incident on the optical path angle variable unit.
The hologram recording / reproducing apparatus according to claim 1,
A detection unit for detecting a light beam emitted from the optical component;
The hologram recording / reproducing apparatus, wherein the optical axis variable unit tilts the optical axis of the emitted light of the optical axis variable unit based on the signal of the detection unit.
The hologram recording / reproducing apparatus according to claim 1,
A detector for detecting the signal light and the reference light;
The hologram recording / reproducing apparatus characterized in that the optical axis variable unit displaces the optical axis of the emitted light of the optical axis variable unit in a direction parallel to the optical axis based on the signal of the detection unit.
The hologram recording / reproducing apparatus according to claim 3,
A detection unit for detecting a light beam emitted from the optical component;
The hologram recording / reproducing apparatus, wherein the optical axis variable unit tilts the optical axis of the light beam incident on the pinhole based on the signal intensity detected by the detection unit.
The hologram recording / reproducing apparatus according to claim 4,
A detection unit for detecting a light beam emitted from the optical component;
The hologram recording / reproducing apparatus, wherein the optical axis variable unit tilts an optical axis of a light beam incident on the intensity distribution conversion unit so that a spot shape of the detection unit is substantially minimized.
The hologram recording / reproducing apparatus according to claim 4,
A detection unit for detecting a light beam emitted from the optical component;
The hologram recording / reproducing apparatus, wherein the optical axis variable unit tilts an optical axis of a light beam incident on the intensity distribution conversion unit based on information on wavefront aberration detected by the detection unit.
The hologram recording / reproducing apparatus according to claim 4,
A detection unit for detecting a light beam emitted from the optical component;
The hologram recording / reproducing apparatus, wherein the optical axis variable unit displaces an optical axis of a light beam incident on the intensity distribution conversion unit based on information on an intensity distribution detected by the detection unit.
The hologram recording / reproducing apparatus according to claim 5,
A detector for detecting the signal light and the reference light;
The hologram recording / reproducing apparatus, wherein the optical axis variable unit changes the position of the optical axis of the light beam incident on the optical path angle variable unit based on the signal intensity detected by the detection unit.
The hologram recording / reproducing apparatus according to claim 5,
A detector for detecting the signal light and the reference light;
When the adjustment medium having a first light-shielding part that shields the signal light and a second light-shielding part that shields the peripheral part of the reference light is arranged at a position where the signal light and the reference light intersect,
When only the signal light is incident, the adjustment medium is moved so that the signal intensity of the detection unit is minimized,
A hologram recording / reproducing apparatus, wherein the optical axis is adjusted by the optical axis variable unit so that the signal intensity of the detection unit becomes maximum when only the reference light is incident.
The hologram recording / reproducing apparatus according to claim 5,
A detector for detecting the signal light and the reference light;
By detecting the signal light from the first lens unit, the position of the detection unit is determined,
Then, the hologram recording / reproducing apparatus characterized in that the position of the optical axis of the light beam incident on the optical path angle variable unit is changed.
The hologram recording / reproducing apparatus according to claim 14,
The hologram recording / reproducing apparatus, wherein the detection unit is an image sensor.
The hologram recording / reproducing apparatus according to claim 1,
The second lens unit and the optical path angle variable unit are held in the same housing,
A hologram recording / reproducing apparatus comprising a mechanism for moving the casing in a direction substantially parallel to an optical axis direction incident on the casing.
The hologram recording / reproducing apparatus according to claim 1,
The second lens unit and the optical path angle variable unit are held in the same housing,
A hologram recording / reproducing apparatus comprising a mechanism for moving the casing in a direction at least substantially perpendicular to the optical axis direction incident on the casing.
A hologram recording / reproducing apparatus of a two-beam angle multiplexing system,
A light source that emits a light beam;
A branching section for branching the light beam emitted from the light source section into signal light and reference light;
A spatial light modulator for adding two-dimensional data to the signal light;
A first lens unit for irradiating the optical information recording medium with the signal light;
A second lens unit for injecting the reference light at substantially the same position as the signal light in the optical information recording medium;
An optical path angle variable unit for changing an incident angle of the reference light incident on the optical information recording medium;
With
A hologram recording / reproducing apparatus characterized in that the signal light incident on the first lens unit is displaced by changing the output of the two-dimensional data of the spatial light modulator.
An optical axis correction method for incident light of an optical component in a hologram recording / reproducing apparatus of a two-beam angle multiplexing system,
The hologram recording / reproducing apparatus comprises:
A light source that emits a light beam;
A branching section for branching the light beam emitted from the light source section into signal light and reference light;
A spatial light modulator for adding two-dimensional data to the signal light;
An optical path angle variable unit for changing the incident angle of the reference light incident on the optical information recording medium,
An optical path from the light source part to the branch part is a common optical path,
An optical path from the branching section through the spatial light modulator to the optical information recording medium is a signal optical path,
When the optical path from the branch part to the optical path angle variable part is a reference optical path,
After correcting the inclination or position of the optical axis of the incident light of the optical component in the common optical path, the inclination or position of the optical axis of the incident light of the optical component in the signal optical path and the reference optical path is corrected. A characteristic optical axis correction method.
The optical axis correction method according to claim 19,
Correction of the inclination or position of the optical axis of the incident light of the optical component in each of the common optical path, the signal optical path, and the reference optical path is performed in the order of the optical components close to the light source unit. Correction method.