JP2005276354A - Recording and reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording and reproducing apparatus which can realize recording and reproducing of an optimum signal to the hologram memory as a mass record medium by a simple constitution. <P>SOLUTION: The recording and reproducing apparatus performs recording and reproducing of information to an optical recording medium which is provided with a hologram recording layer on a face of one side and a groove or an address pit for detecting a recording or reproducing position on a face of another side at the time of recording and reproducing of a hologram. The recording and reproducing apparatus is characterized by performing recording and reproducing of information on an optical disk by using detection light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a recording / reproducing apparatus that records information on a recording layer of an optical recording medium and reproduces the recorded information.

  In recent years, rewritable optical discs such as phase change type and magneto-optical type are widely used as information recording media. In order to further increase the recording density of these optical discs, techniques such as reducing the beam spot diameter and shortening the distance between adjacent tracks or adjacent bits are required.

  As described above, the density of optical discs is increasing year by year. However, since the above optical disc records data in a plane, the recording density is limited to the diffraction limit of light, and physical recording of high density recording is performed. Approaching the limit. Therefore, in order to further increase the capacity, three-dimensional (volume type) multiplex recording including the depth direction is required.

  Therefore, a hologram memory having both a large capacity derived from a three-dimensional multiple recording area and a high speed derived from a two-dimensional batch recording / reproducing system has attracted attention as a next-generation computer file memory. Hologram memory, for example, irradiates a recording medium formed by sandwiching a recording layer made of a photopolymer or the like between two glass plates with object light corresponding to recording information and reference light, and is generated by both lights The recorded interference fringes are recorded as a change in the refractive index of the recording material, and when reproducing information, only the reference light is irradiated to the recorded interference fringes and optical information corresponding to the recorded information is extracted. It is.

Since this hologram memory can multiplex-record a plurality of two-dimensional data in the same area, it has been attracting attention as a terabyte memory having a huge recording capacity while having the same shape as a CD or the like. On the other hand, in order to perform high-density information recording, high-accuracy positioning control is necessary. For such positioning control, for example, a technique shown in Patent Document 1 has been proposed.
JP 10-124872 A

  However, according to the technique described in Patent Document 1, since the hologram recording / reproducing optical system and the optical system for detecting position information are configured with the same optical path, the hologram recording / reproducing optical system is used. Is reduced, the degree of freedom of the reproducing optical system of the optical recording medium is reduced, and there is a problem that it is difficult to cope with a conventional optical disc.

  Accordingly, the present invention has been made in view of the above-described problems, and provides a recording / reproducing apparatus capable of realizing optimum signal recording / reproduction with respect to a hologram memory as a large-capacity recording medium with a simple configuration. Objective.

  The invention according to claim 1 has the same direction as the optical recording medium having a hologram recording layer on one surface and provided with grooves or address pits on the other surface for detecting a recording / reproducing position during hologram recording / reproducing. A recording / reproducing apparatus that irradiates object light and reference light from a light source, records and reproduces a hologram, and irradiates the groove or address pit with detection light to detect the recording / reproducing position of the hologram. The recording / reproducing apparatus is characterized in that information is recorded / reproduced on / from an optical disc using the detection light.

  According to the present invention, it is possible to record or reproduce a conventional thermal recording type optical disc or a read-only ROM type optical disc (hereinafter collectively referred to as an optical disc) with light for recording / reproducing position detection used at the time of hologram recording / reproduction, An optical disk compatible hologram recording / reproducing apparatus can be provided.

The invention according to claim 2 proposes a recording / reproducing apparatus according to claim 1, wherein the object light, the reference light, and the detection light are generated by the same light source. .
According to the present invention, since the detection light can be generated with the same light source, the apparatus can be reduced in size and cost.

According to a third aspect of the present invention, in the recording / reproducing apparatus according to the first or second aspect of the present invention, the recording / reproducing apparatus further comprises wavelength variable means for varying the wavelength of the detection light according to the type of the optical disc. A playback device is proposed.
According to the present invention, since light of a plurality of wavelengths can be used as the detection light source, recording / reproducing of a blue (wavelength: about 400 nm), red (wavelength: about 650 nm) or infrared (wavelength: about 800 nm) optical disc Can be provided.

According to a fourth aspect of the present invention, in the recording / reproducing apparatus according to the first or second aspect, the optical system for the object light and the reference light and the optical system for the detection light are integrated when the hologram is recorded / reproduced. A recording / reproducing apparatus has been proposed in which movement control is performed and only the optical system of the detection light is moved and controlled when information is recorded and reproduced on the optical disc.
According to the present invention, the movement of the entire optical system is controlled during hologram recording / reproduction, so that the object light and the reference light can be controlled to the optimum positions on the recording medium recording surface. Further, the image on the two-dimensional photodetector is not moved or blurred by the movement control. Further, during optical disc recording or reproduction, only the detection light irradiation optical system is controlled to move, so that the weight of the movable portion is reduced and high-speed control is possible.

  The invention according to claim 5 has the same direction as the optical recording medium having a hologram recording layer on one surface and provided with grooves or address pits on the other surface for detecting a recording / reproducing position at the time of recording / reproducing the hologram. A recording / reproducing apparatus that irradiates object light and reference light from a light source, records and reproduces a hologram, and irradiates the groove or address pit with detection light to detect the recording / reproducing position of the hologram. A recording / reproducing apparatus that records and reproduces information on an optical disk using the object light is proposed.

  According to the present invention, recording / reproduction of a thermal recording type recording medium or reproduction of a ROM medium in which concave or convex pits are formed in advance is performed by object light. Alternatively, with respect to a ROM medium in which concave or convex pits are formed in advance or an optical disk in which one side is a thermal recording type recording medium and the other side is a ROM medium, the object light can be used without switching the front and back of the optical disk. One side can be recorded or reproduced on one side with detection light.

According to the present invention, there is an effect that an optimum signal recording / reproduction with respect to a hologram memory as a large-capacity recording medium can be realized with a simple configuration.
Further, in the hologram memory medium, there is an effect that it is possible to realize a compatible optical system for recording / reproduction of a thermal recording type optical disc or a read-only ROM type optical disc.

  Hereinafter, a recording / reproducing apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 1, a recording / reproducing apparatus according to an embodiment of the present invention includes a hologram memory medium 1, a spindle motor 2, an optical pickup 3, a feed motor 4, a signal processing IC 5, and a CPU (CPU: Central Processing Unit) 6 and a driver IC 7.

  The hologram memory medium 1 is a recording medium formed by sandwiching a recording layer made of a photopolymer or the like as a recording material between a substrate made of a glass plate or the like and a reflection layer, and includes object light and reference light corresponding to recorded information. Is recorded on the recording area, and the interference fringes generated by both lights are recorded as a change in the refractive index of the recording material. When reproducing information, the recorded interference fringes are irradiated only with reference light, and optical information corresponding to the recorded information is extracted.

The spindle motor 2 is a driving device for rotating the hologram memory medium, for example, at a constant linear velocity when the hologram memory medium has a disk shape, and the rotation speed and the like are controlled by the output of the driver IC 7.
The optical pickup 3 includes a laser light source using a semiconductor laser, an objective lens driven by a collimator lens, a focusing actuator or a tracking actuator, optical components such as a polarizing beam splitter, and a two-dimensional light detection array serving as a light receiving element. ing.

The feed motor 4 is a mechanism for sending the optical pickup from the inner periphery to the outer periphery of the hologram memory medium 1, for example, and controls the position of the optical pickup 3 by a drive signal of a tracking actuator.
The signal processing IC 5 generates a reproduction signal based on the amount of light returned from the hologram memory medium 1 that has entered the two-dimensional photodetection array, and also detects a focus error signal (FE) that detects a defocus of the irradiation laser in the optical pickup 3. Is generated by the astigmatism method based on the return light amount obtained by the light receiving element in the optical pickup 3, and a track error signal (TE) for detecting the track shift of the irradiation laser in the optical pickup 3 is further pushed, for example. Generated by the pull method or the like. Further, based on the generated FE and TE, a focusing drive signal (FODRV) and a tracking drive signal (TRDRV) are generated.

The CPU 6 controls the entire apparatus based on a control program stored in a ROM (ROM: Read Only Memory) or the like. In the present invention, various servo operations are controlled in the operation of recording and reproducing information on the hologram memory medium 1.
The driver IC 7 receives the focusing drive signal (FODRV), the tracking drive signal (TRDRV), or the spindle control signal generated in the signal processing IC 5 and amplifies them to a desired size, and then the focusing actuator and tracking actuator Alternatively, it is supplied to a spindle motor or the like. The feed motor drive signal generated from the tracking drive signal (TRDRV) is amplified to a desired magnitude, and then supplied to the feed motor.

Various methods have been proposed as a method for recording information on the hologram memory medium. Of these, a shift multiplexing method as a typical recording method will be described with reference to FIG.
The shift multiplexing method is a method in which information is recorded on the recording layer of the hologram memory medium 1 while the information recording area is shifted little by little. In order to perform the recording by the shift multiplexing method, it is necessary to make the reference light a spherical wave, or make the phase, amplitude, traveling direction, etc. spatially random.

  Specifically, the shift multiplexing method will be described with reference to FIG. 4. First, the object light 56-1 (information 1) is irradiated to a certain area, and similarly, the position irradiated with the object light 56-1 is referred to. The light 57-1 is irradiated to interfere with these, and the interference fringes 58-1 are recorded in volume. Next, the recording position is shifted by shifting the irradiation spot by a small amount, and similarly, the object beam 56-2 (information 2) and the reference beam 57-2 are irradiated at the same position to cause interference. Volume stripes 58-2 are recorded. Thereafter, information is multiplexed and recorded while sequentially shifting the recording position little by little.

  In the reproduction operation of information recorded by the shift multiplexing method, the position of the recorded interference fringe 58-1 is irradiated with the reference light 57-1, and only the interference fringe 58-1 recorded at that position by the reference light. Diffracted light can be obtained. Therefore, the two-dimensional data of information 1 can be reproduced by using the reference beam 57-1.

  In this example, only the shift multiplexing in the X direction has been described, but similarly, the same shift multiplexing recording can be performed in the Y direction. Therefore, enormous multiplex recording is possible by performing shift multiplex recording in the X direction and Y direction together.

Next, with reference to FIG. 2 and FIG. 3, the operation and configuration of the optical system of the present invention corresponding to the recording and reproduction of information on the hologram memory medium, particularly the shift multiplexing method will be described.
The light (for example, S-polarized light) emitted from the semiconductor laser 11 in the optical pickup 3 is converted into parallel light by the lens 12, and the plane of polarization is rotated in the half-wave plate (λ / 2 plate) 13. The P-polarized light passes through the polarization beam splitter (PBS) 14, and the polarization plane is further rotated in the λ / 2 plate 15.

  The S-polarized light whose polarization plane has been rotated is reflected by a polarization beam splitter (PBS) 16 and given two-dimensional data by a spatial light modulator (SLM) 17. The converted two-dimensional data is transmitted through the λ / 2 plate 18 in the S-polarized state, and condensed by the objective lens (OL) 19 in the vicinity of the recording layer 103 of the hologram memory medium 1. This light becomes object light 50.

  On the other hand, the light converted to S-polarized light by the λ / 2 plate 13 is reflected by the PBS 14 and is collected by the wavefront conversion element 21 having the function of condensing and / or spatially randomizing the phase and / or amplitude of the light beam. Then, the vicinity of the recording layer 103 irradiated with the object light of the hologram memory medium 1 is irradiated from the same side as the object light. This becomes the reference beam 51.

  In the recording layer 103 of the hologram memory medium 1 irradiated with the object light 50 and the reference light 51, the object light 50 and the reference light 51 interfere with each other, and interference fringes are volume-recorded. The light amounts of the object light 50 and the reference light 51 can be arbitrarily set by rotating the λ / 2 plates 13 and 15 around the optical axis. Therefore, the light amounts of the object light 50 and the reference light 51 may be arbitrarily selected so that the interference fringe pattern becomes the clearest.

Here, the wavefront conversion element 21 is an optical element having an optical function of randomizing the reference light. Hereinafter, the details will be described with reference to FIG.
As described above, in order to realize shift multiplex recording, it is necessary to make the wavefront of the reference light completely random in the light beam or to make it a spherical wave. This is because information before and after the shift is reproduced at the same time if the recorded data in the overlapping area before and after the shift has a correlation with the wavefront of the reference light before and after the shift.

  The wavefront conversion element 21 in the present embodiment has a function of spatially and randomly converting the wavefront of the reference light in phase, amplitude, and traveling direction, and an example thereof is irregularly arranged as shown in FIG. The black, gray, and white regions have regions with optically different thicknesses. Therefore, the light transmitted or reflected through these regions is converted into spatially random light by the optical action of these thicknesses.

  Moreover, in each area | region of black, gray, and white, each area | region can also be comprised so that the transmittance | permeability or reflectance of light may differ. Also in this case, the light transmitted or reflected through these regions is converted into light having a random amplitude or intensity spatially by the optical action due to the difference in transmittance or reflectance.

  Further, in each of the black, gray, and white regions, each region may have an angle that makes an incident angle or a reflection angle different with respect to transmitted light or reflected light. Also in this case, light transmitted or reflected through these regions is converted into light whose traveling direction is spatially random due to the optical action due to the difference in incident angle or reflection angle.

  In this embodiment, each example has been described in three stages of black, gray, and white. However, the smaller the level and the smaller the area of each region, the more random the light phase, amplitude, etc. Therefore, crosstalk during reproduction due to multiple recording is reduced.

Further, by using a hologram, the light flux of the reference light can be randomized. A case where the hologram 63 is used as a wavefront conversion element will be described with reference to FIGS. 6 and 7. 6 is, for example, light transmitted or reflected by the wavefront conversion element 21 illustrated in FIG. 5 or light transmitted through a lens.
Using this light as object light, a hologram 63 is produced in which interference fringes are recorded by interference with the reference light 62. Then, as shown in FIG. 7, when the hologram 63 is irradiated with the reference light 65, the light beam is spatially irregularly transmitted, that is, transmitted or reflected through an optical element that changes the phase or amplitude (intensity) or the traveling direction of the light beam. Light or light 64 transmitted through the lens is generated in the direction of the arrow in the figure.

  The random light 64 is a light beam that is equivalent to the random light 61 and whose traveling direction is opposite. In order to combine the function of the hologram as a wavefront conversion element, the luminous flux of the object light 61 is spatially irregular, that is, transmitted or reflected through an optical element and a lens that change both phase and amplitude (intensity). The hologram 21 may be produced by interfering with the reference light 62 and recording interference fringes as the light.

  Thereby, as shown in FIG. 7, if the hologram 63 is irradiated with the reference light 65, the combined random light 64 is generated in the direction of the arrow in the figure. The random light 64 is a light beam that is equivalent to the random light 61 and whose traveling direction is opposite. In addition, during mass production of holograms, mass production is possible at low cost with good reproducibility by transferring the hologram pattern to a mold and further transferring it to glass, resin or the like.

  Next, when reproducing the recorded data, the λ / 2 plate 15 is rotated around the optical axis, and the light transmitted through the λ / 2 plate 15 is transmitted through the PBS 16 as only the P-polarized light component. That is, only the reference light that is S-polarized light is irradiated to the interference fringes formed in the recording area of the recording layer 103 of the hologram memory medium 1.

  The light diffracted by the recording layer 103 is reflected by the reflective film layer 102 of the hologram memory medium 1, enters the OL 19, is converted into a parallel light beam, and is then converted into P-polarized light by the λ / 2 plate 18. The converted P-polarized light passes through the SLM 17 and the PBS 16 and is condensed on the two-dimensional photodetection array 33 by the condenser lens 32 to reproduce the two-dimensional data.

  However, at the time of signal reproduction, the SLM 17 needs to be in the entire region transmission state or be out of the optical path. Further, the λ / 2 plate 18 needs to rotate the optical axis at 45 degrees with respect to the S-polarized light.

  In this embodiment, after recording the interference fringes 38-1, the optical unit 22 can be moved by a predetermined amount, and the recording / reproducing operation can be continued successively. Since the optical unit 22 is built in the optical pickup 3, the optical unit 22 can be moved by a predetermined amount by controlling the feed motor 4. Therefore, highly accurate positioning control can be realized with respect to the object light and the reference light without using a special control mechanism.

Next, a method for controlling object light will be described with reference to FIG.
The light emitted from the semiconductor laser 11 and transmitted through the PBS 16 is reflected by the deflecting prisms (DP) 23, 24, and 25, and then transmitted through the PBS 26 to be circularly polarized by the λ / 4 plate 27 and incident on the OL 28. To do. The light condensed by the OL 28 enters the servo information area of the hologram memory medium 1.

  The servo information area is provided with concave or convex positioning information. The light reflected by the reflective film layer 102 is again made substantially parallel light by the OL 28, passes through the λ / 4 plate 27, and becomes S-polarized light. The S-polarized light is reflected by the PBS 26, collected by the condenser lens 29, given astigmatism by the cylindrical lens 30, and enters the servo light receiving element 31.

  The method of detecting the position of the detection light is an astigmatism method in the direction perpendicular to the surface of the hologram memory medium 1 (focusing direction), which is common in optical disks, and orthogonal to the concave or convex portions in the surface of the hologram memory medium 1. A push-pull method or the like can be used for the direction of tracking (tracking direction). The position in the direction of the concave or convex portion (track direction) can be detected by providing address information in the concave or convex portion.

  Further, the hologram memory medium 1 shown in the present embodiment includes a cover layer 100, substrates 101 and 104, a reflective film layer 102, and a recording layer 103, as shown in FIG. A concave portion or a convex portion is formed in advance on the substrate 101, a reflective film layer 102 and a recording layer 103 are laminated thereon, and a substrate 104 is disposed thereon.

  The width A of the concave portion or convex portion is about 0.1 to 2 (μm) although it depends on the optical system. Further, the interval B between the concave portions or the convex portions is about 0.1 to 10 (μm). The interval B is set to be approximately equal to the value of the divisor of the shift amount of the shift multiplex recording in the direction (X direction) orthogonal to the groove direction of the convex portion or the concave portion. The outer shape of the recording medium may be a disk type or a card type.

  Assuming that the hologram memory medium 1 is a portable medium, the thickness direction (focusing direction) and the in-plane direction (tracking direction) of the object light 50 and the reference light 51 irradiated to the recording layer 103 between recording devices that perform recording and reproduction. The position is not fixed. Further, when the hologram memory medium 1 is rotated (moved) for recording / reproduction even in the same recording apparatus, the thickness direction (focusing) of the object light 50 and the reference light 51 irradiated on the recording layer 103 due to surface deflection and eccentricity. Direction) and the in-plane direction position (tracking direction) will be shifted.

  The shift between the object beam 50 and the reference beam 51 is controlled by moving the OL 28 in the focusing direction or in the track orthogonal direction based on the focusing control signal and the track control signal (output of the light receiving element 31). The object beam 50 and the reference beam 51 can be irradiated to a desired position by controlling the movement of the actuator (not shown) configured to move the wavefront conversion unit 21 integrally in the focusing direction or the track orthogonal direction.

  At this time, when the amount of movement is large, in order to form an accurate image on the two-dimensional light detection array 33, it may be necessary to control the movement of the condenser lens 32 in the optical axis direction and the optical axis orthogonal direction. Further, the deviation between the object beam 50 and the reference beam 51 is controlled by moving the entire detection optical system 35 in the focusing direction or the track orthogonal direction based on the focusing control signal and the track control signal (output of the light receiving element 31). Alternatively, by moving and controlling the entire hologram recording / reproducing optical system 34 in the focusing direction or the direction perpendicular to the track, the object beam 50 and the reference beam 51 can be irradiated to desired positions. When the entire optical system is moved, the image on the two-dimensional photodetection array 33 is not shifted.

  In addition, the detection optical system in this embodiment has the same configuration as that of a conventional recording / reproducing optical system for an optical disc (DVD, CD, etc.). That is, in the recording apparatus and reproducing apparatus in the present embodiment, as shown in FIG. 8, recording and reproducing can be performed by inserting the recording surface of the optical disc 60 toward the detection light side of the optical system.

  At this time, by rotating the λ / 2 plates 13 and 15 around the optical axis so as to be all P-polarized light, all the light of the semiconductor laser 11 is guided to the detection optical system. When recording / reproducing an optical disc (DVD, CD, etc.), the hologram recording / reproducing optical system 34 and the detection optical system 35 may be controlled to move together, or the hologram recording / reproducing optical system 34 is fixed and the detecting optical system is fixed. Only 35 may be controlled to move.

  Next, a method for switching the wavelength of the detection light will be described with reference to FIG. Now, let the wavelength of the semiconductor laser 1 be about 400 nm, for example. The light emitted from the semiconductor laser 1 is reflected by the DP 24 and subsequently reflected by the dichroic prism 39. The light reflected by the dichroic prism 39 passes through the lens 40 for correcting chromatic aberration, passes through the PBS 41, is circularly polarized by the λ / 4 plate 42, and is condensed on the recording layer of the blue-compatible optical disc 60 by the OL 43. To do.

  The light reflected from the optical disk 60 is reflected by the PBS 41, condensed by the condenser lens 29, given astigmatism by the cylindrical lens 30, and enters the signal detection light receiving element 31. On the other hand, the light emitted from the light source 37 having a wavelength of 650 nm is converted into substantially parallel light by the lens 38, passes through the dichroic prism 39, and enters the PBS 41. Thereafter, the light enters the signal detection light receiving element 31 through the same optical path as that of 400 nm light.

  At this time, the optical disk 60 is a DVD disk. In the positioning control, the hologram recording / reproducing optical system 34 and the detecting optical system 36 may be controlled to move together, or the hologram recording / reproducing optical system 34 is fixed and only the detecting optical system 36 is controlled to move. Also good.

Therefore, according to the present embodiment, by switching the wavelength of the detection light of the hologram recording / reproducing optical system, it is possible to perform recording / reproducing of a plurality of types of optical discs. An optical system capable of reproduction can be realized.
In addition, the optical system of this embodiment can also perform hologram recording / reproduction of a hybrid disk in which a hologram memory medium and a thermal recording type optical disk or a read-only ROM type optical disk are integrated, and recording / reproduction of an optical disk.

Next, a method of recording / reproducing an optical disk with object light for hologram recording will be described with reference to FIG.
First, the λ / 2 plate 13 is rotated around the optical axis so that all of the light is P-polarized light and the PBS 14 is transmitted. Next, the λ / 2 plate 15 is rotated around the optical axis and the plane of polarization is tilted. The P-polarized light passes through the PBS 16 and is collected by the OL 28 on the lower surface of the double-sided optical disc 61. The reflected light enters the light receiving element 31, and generates an information reproduction signal, focus, and track error signal.

  The focus error detection method is, for example, the astigmatism method, and the track error detection method is, for example, the push-pull method. The S-polarized light is collected by the OL 19 on the upper surface of the double-sided optical disc 61, and the reflected light is incident on the two-dimensional light detection array 33 to generate an information reproduction signal, focus, and track error signal. The focus error detection method is, for example, a beam size method generally used for optical disks, and the track error detection method is, for example, a push-pull method.

  At this time, the SLM 17 is set in the entire region transmission state. The λ / 2 plate 18 is composed of four λ / 8 plates. When acting as a λ / 2 plate (at the time of hologram recording / reproduction), the four fast axes are made to coincide, and When acting as a / 4 plate (at the time of optical disc recording / reproduction), the fast axes of two of the four sheets are made to coincide with each other, and the remaining two fast axes are made orthogonal. The OLs 19 and 28 can perform focus and track control independently by their control signals. According to the present embodiment, information can be reproduced simultaneously on both sides of a double-sided type optical disc. Further, it is possible to appropriately perform recording or reproduction on both sides without turning the optical disc over.

As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the specific configuration is not limited to these embodiments, and includes design changes and the like within a scope not departing from the gist of the present invention. It is. For example, in the present embodiment, it has been described that the optical pickup is moved to record or reproduce information on the hologram memory medium. However, the present invention is not limited to this. For example, when the recording medium has a card shape, the optical pickup May be fixed and the movement of the hologram memory medium may be controlled.
In this embodiment, the thermal recording type or the ROM type is exemplified as the optical disc. However, the present invention is not limited to this, and other types of optical discs may be used.

It is a block diagram of the recording / reproducing apparatus in a present Example. It is a block diagram of the optical system in a present Example. It is a block diagram of the hologram memory medium in a present Example. It is a conceptual diagram of a shift multiplexing system. It is the figure which showed the wavefront conversion element in a present Example. It is a figure which shows the effect | action of the light at the time of using a hologram as a wavefront conversion element. It is a figure which shows the effect | action of the light at the time of using a hologram as a wavefront conversion element. It is a block diagram of the optical system at the time of using an optical disk. It is a block diagram of the optical system which converts the wavelength of detection light. It is a block diagram of the optical system in the case of recording / reproducing an optical disk with the object light for hologram recording.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hologram memory medium, 2 ... Spindle motor, 3 ... Optical pick-up, 4 ... Feed motor, 5 ... Signal processing IC, 6 ... CPU, 7 ... Driver IC, DESCRIPTION OF SYMBOLS 11 ... Semiconductor laser, 12, 38 ... Lens, 13, 15, 18 ... 1/2 wavelength plate, 14, 16, 26, 41 ... Polarizing beam splitter, 17 ... Spatial light modulation 19, 28, 43 ... objective lens, 29, 32 ... condensing lens, 21 ... wavefront conversion element, 22 ... optical unit, 23, 24, 25 ... polarizing prism (DP , 27, 42,..., 1/4 wavelength plate, 30, cylindrical lens, 31, light receiving element for servo, 33, two-dimensional light detection array, 37, light source, 39. ..Dichroic prism, 40 ... for correcting chromatic aberration Lens, 60 ... optical disk, 100, 104 ... substrate, 103 ... recording layer, 102 ... reflective layer

Claims (5)

Object light and reference light from the same direction on an optical recording medium having a hologram recording layer on one surface and a groove or address pit for detecting the recording / reproducing position during hologram recording / reproduction on the other surface A recording / reproducing apparatus that irradiates and records and reproduces a hologram, and irradiates the groove or address pit with detection light to detect the recording / reproducing position of the hologram,
A recording / reproducing apparatus for recording / reproducing information on / from an optical disc using the detection light.   The recording / reproducing apparatus according to claim 1, wherein the object light, the reference light, and the detection light are generated by the same light source.   3. The recording / reproducing apparatus according to claim 1, further comprising a wavelength variable unit that varies a wavelength of the detection light according to a type of the optical disk.   When the hologram is recorded and reproduced, the object light and reference light optical system and the detection light optical system are integrally moved and controlled, and when the information is recorded and reproduced on the optical disk, only the detection light optical system is used. The recording / reproducing apparatus according to claim 1, wherein movement control of the recording / reproducing apparatus is performed. Object light and reference light from the same direction on an optical recording medium having a hologram recording layer on one surface and a groove or address pit for detecting the recording / reproducing position during hologram recording / reproduction on the other surface A recording / reproducing apparatus that irradiates and records and reproduces a hologram, and irradiates the groove or address pit with detection light to detect the recording / reproducing position of the hologram,
A recording / reproducing apparatus for recording / reproducing information on / from an optical disc using the object light.

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