JP3574054B2 - Holographic optical recording medium, recording device and reproducing device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a holographic optical recording medium. , Recording device and It relates to a playback device.
[0002]
[Prior art]
Conventionally, as volume holographic recording methods, research and development on methods such as angle multiplex recording, wavelength multiplex recording, and shift multiplex recording have been performed. Here, “holographic recording” means recording information in the form of a hologram. In any recording method, at the time of recording, object light and reference light interfere with each other in an optical recording medium, and interference fringes are recorded as a hologram. By irradiating the optical recording medium with reference light at the same conditions as during recording when reproducing the wavefront of light (however, usually, the information recorded on the hologram is used during reproduction by using a lower-power reference light than during recording). It is restored and played.
[0003]
[Problems to be solved by the invention]
In conventional holographic recording / reproducing (writing information by holographic recording and reading information by reproducing a wavefront from a hologram), a commutative optical recording medium (different recording) Equipment and There is no example in which an optical recording medium that can be used in a reproducing apparatus is used. The reason is that the accuracy of the wavefront reproduction conditions is strict, and the S / N ratio is reduced only by the occurrence of an error in the incident angle or the position of the reference light on the optical recording medium, making it difficult to reproduce the original information. There was something.
[0004]
In order to overcome the above-mentioned problems, it is conceivable to make the recording layer of the optical recording medium thin to reduce the selectivity of reproduction and to give a margin to the optical recording medium itself. There is a problem that the multiplicity of multiplex recording, which is a characteristic, is reduced and high-density recording cannot be performed.
[0005]
As described above, in the above-described conventional optical recording medium, if it is to be handled as a replaceable optical recording medium, a problem such as positioning occurs, and high-density data cannot be recorded and reproduced. Further, in order to secure a margin, a thin-film recording layer having a small volume is required, and a sufficient recording density (for example, 200 GB / CD) cannot be achieved.
[0006]
The present invention has been made in view of the above problems, and a problem to be solved by the present invention is to provide a holographic optical recording medium capable of irradiating a highly accurate reference light and an object light. And Information recording using the holographic optical recording medium And Record to play Equipment and A playback device is provided.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides, as described in claim 1,
In a holographic optical recording medium having a substrate provided with a marker whose position can be detected by light and a hologram recording layer provided on the substrate, the marker is provided with the hologram recording layer of the substrate. The marker and the hologram recording layer are provided on the surface on the side opposite to the side, so that the marker and the hologram recording layer are arranged apart from each other by a distance according to the thickness of the substrate. Construct a holographic optical recording medium.
[0008]
Further, the present invention provides, as described in claim 2,
A holographic optical recording medium having two substrates and a hologram recording layer sandwiched between the two substrates, wherein at least one of the substrates is provided with a marker capable of detecting a position by light. The marker is provided on the surface of the substrate opposite to the side on which the hologram recording layer is provided, so that the marker and the hologram recording layer are separated by a distance corresponding to the thickness of the substrate. Is located A holographic optical recording medium characterized by the above features.
[0009]
Further, the present invention provides, as described in claim 3,
The said marker is a circular recessed part, a circular convex part, a groove | channel, or a linear convex part, The Claim of Claim 1 or 2 characterized by the above-mentioned. Construct a holographic optical recording medium.
[0010]
Further, the present invention provides, as set forth in claim 4,
A means for recording a hologram on the holographic recording layer of the holographic optical recording medium according to any one of claims 1 to 3, and positioning of the object light at the time of hologram recording is performed by position detection using the marker light. A recording device including a servo mechanism, wherein the object light at the time of recording the hologram and the light used for detecting the position of the marker pass through the same condenser lens to focus on the marker, and the object A recording apparatus, wherein light and light used for the position detection are not focused on the hologram recording layer. Is composed.
[0012]
Further, the present invention provides 5 As described in
Claim To four The recording apparatus according to claim 1, wherein the object light and the reference light at the time of recording the hologram are configured to be incident on the hologram recording layer while being opposed to each other across the hologram recording layer.
[0013]
Further, the present invention provides 6 As described in
A means for reproducing a wavefront from a hologram recorded on the holographic recording layer of the holographic optical recording medium according to claim 1, and positioning the reference light at the time of reproducing the wavefront with the marker. In a reproducing apparatus provided with a servo mechanism that performs position detection by light, a reference beam at the time of wavefront reproduction and light used for position detection of the marker pass through the same condenser lens to focus on the marker. Wherein the reference light at the time of the wavefront reproduction and the light used for the position detection are not focused on the hologram recording layer.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. Recording of a hologram on a hologram recording layer is simply called recording, and reproduction of a wavefront from a hologram is simply called reproduction.
[0018]
In the present invention, a marker for servo (in this case, positioning of reference light or object light) and addressing (in this case, selection of a hologram) is provided to the holographic optical recording medium. Thus, at the time of recording, the marker allows the appropriate reference light and object light to interfere with each other in the hologram recording layer with high accuracy, and the generated interference fringes can be recorded on the hologram recording layer. In, by tracing this marker, it is possible to accurately reproduce and reproduce recorded data.
[0019]
By using the above-described markers for servo and addressing on the holographic optical recording medium, the hologram is irradiated with the reference light with high accuracy during reproduction, and highly compatible recording and reproduction can be performed in different recording and reproduction systems. Such a holographic optical recording medium can be used as a replaceable optical recording medium. Furthermore, since addressing is possible using a marker (the position of a desired marker can be specified by, for example, the number of markers from a reference position), the location of desired data can be determined before performing hologram reproduction. Search is possible without performing hologram reproduction. Of course, a marker dedicated to addressing different from the above marker may be provided.
[0020]
【Example】
[Example 1]
FIG. 1 is a configuration diagram of an example of a holographic optical recording medium according to the present invention, and FIG. 2 is a diagram for recording information using the holographic optical recording medium. as well as To play It is both a recording device and a playback device A configuration diagram of the recording / reproducing apparatus is shown in FIG. 3, a principle explanatory diagram at the time of recording, and FIG. 4 is a principle explanatory diagram at the time of reproduction.
[0021]
FIG. 1A is a perspective view showing an entire holographic optical recording medium according to the present invention, and FIG. 1B is an enlarged sectional view of the optical recording medium. This holographic optical recording medium has a disk shape as shown in FIG. However, a holographic optical recording medium in the form of a card can also be used.
[0022]
As shown in FIG. 1B, this holographic optical recording medium is provided on a substrate 1 transparent to hologram recording light and servo light and on the substrate 1 (the lower surface in FIG. 1). Hologram recording layer 2 provided. On a surface of the substrate 1 opposite to the hologram recording layer 2, a marker 3 having a circular concave shape is provided. As shown in FIG. 1A, the markers 3 are arranged on a track 4 (a concentric circle having a slightly different radius or a spiral having a minute pitch) on the substrate 1. In this case, the marker 3 may be similar to a pit (recess having a length of 0.6 to 3 μm and a width of about 0.4 μm) of the optical disk. Furthermore, in addition to the circular concave portion, a circular convex portion arranged on the track 4, a groove along the track 4, or a linear convex portion (complementary to the groove) is used as the marker 3. be able to. In this case, the “circle” includes an oval.
[0023]
As the hologram recording layer 2, an organic film such as a resist or a photopolymer or an inorganic material film such as lithium niobate or SBN (strontium barium niobate) can be used. When a recording layer that is particularly susceptible to deterioration is used, a passivation protective film is provided.
[0024]
FIG. 2 relates to the present invention. It is both a recording device and a playback device 1 shows an example of the configuration of a recording / reproducing device (transmission type). In the figure, 201 is a holographic optical recording medium according to the present invention, 202 is a servo laser as a servo light source, and 203 is a half mirror that reflects a servo return beam toward a position detector 206. Numeral 204 denotes a half mirror for combining the servo laser light with the object light 209 to enter the condenser lens 205. Reference numeral 205 denotes holographic optical recording by combining the servo laser light and the object light 209. A condensing lens for converging on a marker of the medium 201, receives a servo return beam, and, based on the light intensity distribution thereof, an incident position of the servo laser light on the holographic optical recording medium 201, Is a position detector that obtains the relative positional relationship between the two and returns the positional information to the servo mechanism. Reference numeral 207 denotes a recording / reproducing laser (532 nm, 100 mW), 208 denotes a beam splitter that divides light from the recording / reproducing laser 207 into an object light 209 and a reference light 210, and 211 denotes an optical path of the object light 209 during reproduction. Reference numeral 212 denotes a beam expander that expands a beam so that the object light 209 is incident on the entire spatial light modulator 213. Reference numeral 213 denotes a spatial light modulator that operates according to input information. Reference numeral 214 denotes a reference light. An objective lens (condensing lens for reference light) 210 converges to a marker of the holographic optical recording medium 201, and a reproduction wavefront reconstructs an image pattern on the spatial light modulator 213 on an imaging surface of the CCD 216. 216 is a reproduction lens necessary to perform the operation, and 216 is a CCD for imaging the image pattern. Is a mirror for changing the direction of the reference light 210.
[0025]
At the time of recording, the beam light emitted from the recording / reproducing laser 207 is divided into an object beam 209 and a reference beam 210 by a beam splitter 208. The object light 209 is expanded by the beam expander 212, passes through the spatial light modulator 213, is condensed by the condenser lens 205, and is irradiated on the holographic optical recording medium 201. On the other hand, the reference beam 210 is split by the beam splitter 208, reflected by the mirror 217, and enters the holographic optical recording medium 201. At this time, the condensed object light 209 causes optical interference with the reference light 210 in the holographic recording layer of the holographic optical recording medium 201, and the data (image pattern) formed by the spatial light modulator 213 is formed. Are recorded as interference fringes. At this time, a Z-axis servo (automatic adjustment of the focal position, the Z-axis is parallel to the optical axis) is applied to the condenser lens 205, and the laser light emitted from the servo laser 202 is combined with the object light 209 by the half mirror 204. The light passes through the same optical path and enters the holographic optical recording medium 201 so that the marker is in focus. Further, tracking sampling servo (automatic radial position adjustment of the disk-shaped holographic optical recording medium 201) is always applied, and recording is performed with good reproducibility at a predetermined position even when the holographic optical recording medium 201 is eccentric. If the marker 3 is a circular recess as shown in FIG. 1, servo in the circumferential direction of the holographic optical recording medium 201 becomes possible, and the positional accuracy of recording and reproduction is further improved. When the marker 3 is different from that shown in FIG. 1 and has a groove shape along the track 4, for example, the rotation angle of the holographic optical recording medium 201 is precisely adjusted instead of the servo in the circumferential direction. Holographic recording may be performed by controlling the holographic optical recording medium 201 at a constant speed and performing hologram recording with light pulses at fixed time intervals.
[0026]
Note that a laser having a high coherency is used as the recording / reproducing laser 207, whereas a laser having a low coherency (short coherence distance) is used as the servo laser 202. In the case of FIG. 2, the object light 209 passing through the condenser lens 205 and the reference light 210 reflected by the mirror 217 and passing through the objective lens 214 are both focused spherical waves.
[0027]
In the recording / reproducing apparatus shown in FIG. 2, the object light 209 and the light for performing the servo pass through the same condenser lens 205. By using such a configuration, the number of lenses can be reduced, and the relative positional relationship between the hologram and the marker can be made more accurate. Similarly, the embodiment described later 2 As shown in FIG. 9, the number of lenses can be further reduced by passing the reference light 904 and the light for performing the servo through the same condenser lens 906.
[0028]
During reproduction, the object light 209 is blocked by the shutter 211, and only the reference light 210 enters the holographic optical recording medium 201. When the reference beam 210 is incident on the hologram recorded on the hologram recording layer of the holographic optical recording medium 201, the focused spherical wave of the object beam 209 at the time of recording becomes a divergent spherical wave (toward the direction opposite to the direction at the time of recording). Will be played. The reproduced wavefront passes through the reproducing lens 215 and forms data (formed as an image pattern) formed by the spatial light modulator 213 during recording as a real image on the imaging surface of the CCD 216. The formed real image is converted into an electric signal by the CCD 216, and the signal is subjected to digital processing to reproduce the recorded data.
[0029]
FIG. 3 is a view for explaining the principle during hologram recording in the present invention. In the figure, 301, 302, and 303 are a holographic optical recording medium substrate, a hologram recording layer, and a marker, 304 is reference light, 305 is object light that has passed through a spatial light modulator 306, Reference numeral 306 denotes a spatial light modulator for generating an image pattern carrying input information, reference numeral 307 denotes an objective lens for condensing the reference light 304 toward the hologram recording layer 302, and reference numeral 308 denotes an object light 305 for converting the object light 305 to the hologram recording layer 302. A focusing lens 309 is a recording area in the hologram recording layer 302 where a hologram is formed.
[0030]
The object light 305 carrying information through the spatial light modulator 306 is condensed by the condensing lens 308 and focused on the position of the marker 303 on the back surface of the substrate 301. At this time, as described with reference to FIG. 2, the Z-axis servo is applied to the condenser lens 308, and during recording, the object light 305 is always focused on the position of the marker 303, and warps or undulates on the holographic optical recording medium. Recording can be performed with good reproducibility even if there is
[0031]
FIG. 4 is a view for explaining the principle during holographic reproduction according to the present invention. In the figure, 401, 402, and 403 are a holographic optical recording medium substrate, a hologram recording layer, and a marker, 404 is a servo laser that is a servo light source, and 405 is a servo return beam. Reference numeral 406 denotes a half mirror that reflects the light toward the position detector 408. Reference numeral 406 denotes a condensing lens 407 that combines the laser light for servo with the object light during recording (indicated by a broken line in the drawing and is blocked during reproduction). Reference numeral 407 denotes a half mirror for allowing the laser beam to enter, 407 denotes a condensing lens for converging the laser beam for servo to the marker 403 of the holographic optical recording medium, and 408 receives a return beam for servo, and Calculates the incident position of the servo laser light on the holographic optical recording medium, and feeds back the position information to the servo mechanism. A position detector. Reference numeral 409 denotes a recording area where a hologram is formed in the hologram recording layer 402, reference numeral 410 denotes reference light for reproduction, and reference numeral 411 denotes a condenser lens for condensing the reference light 410 toward the hologram recording layer 402. Reference numeral 412 denotes a reproduction lens for forming a reproduction wavefront on the CCD imaging surface as a reproduction image 413 (real image).
[0032]
The return beam is received by the position detector 408 while the light of the servo laser 404 is focused on the marker by the condenser lens 407 via the half mirrors 405 and 406, and the output of the position detector 408 is used as a feedback signal. The hologram recorded in the recording area 409 of the hologram recording layer 402 by the servo mechanism is placed at the same position as when recording, and the recording area 409 is irradiated with the reference light 410. This reference light 410 is diffracted in the recording area 409 to generate a reproduction wavefront. The reproduced wavefront forms a reproduced image 413 (real image) on the CCD imaging surface through a reproducing lens 412 provided on the back surface of the substrate 401. The recorded data is restored and reproduced by digitally converting the reproduced image 413.
[0033]
FIG. 5 shows a flow of the above data recording process, and FIG. 6 shows a flow of the data reproducing process.
[0034]
In the data recording process, as shown in FIG. 5, first, digital data handled by a computer is encoded as a digital image pattern. This digital pattern is light-modulated as an image image by a spatial light modulator, interferes with a reference light in a holographic optical recording medium, and information is recorded as interference fringes. At this time, the position coordinates of the object light are servo-controlled.
[0035]
In the data reproduction process, as shown in FIG. 6, a marker position where hologram recording has been performed on the optical recording medium is detected, and the recording position is irradiated with reference light. As a result, the reproduction light diffracted from the holographic optical recording medium is subjected to inverse Fourier transform through a lens, and an image pattern is formed on a CCD imaging surface and reproduced as image information. This image is decoded, and the digital data recorded on the holographic optical recording medium is reproduced. Note that a servo is applied to the irradiation position of the reference light.
[0036]
As described above, holographic recording and reproduction can be performed with good reproducibility by forming servo markers on the back surface of the substrate by implementing the present invention.
[ Reference example ]
FIG. To e Of optical recording media reference FIG. 2 shows a configuration diagram of an example. Book reference In the example, as shown in FIG. 7, a servo marker 703 can be seen from the substrate 701 side at the interface between the substrate 701 and the hologram recording layer 702 which is transparent to hologram recording light and servo light. For example, it is provided as a local concave portion, and as a convex portion when viewed from the hologram recording layer 702 side.
[0037]
FIG. 7 shows a configuration diagram of another example of the holographic optical recording medium according to the present invention. In this embodiment, as shown in FIG. 7, a servo marker 703 is provided at the interface between the substrate 701 and the hologram recording layer 702 which is transparent to the hologram recording light and the servo light. When viewed from the hologram recording layer 702 side, it is provided as a local concave portion.
Using the holographic optical recording medium shown in FIG. 7 and the recording / reproducing apparatus in the first embodiment, the holographic recording / reproducing can be performed with good reproducibility by accurately aligning the servo marker 703 with the light irradiation position during recording / reproducing. It was possible. In contrast to the first embodiment, the light for recording / reproducing is incident from the substrate 701 side for recording / reproducing, and the light is incident from the hologram recording layer 702 side for recording / reproducing similarly to the first embodiment. And the same level of recording / reproduction was possible.
[Example 2 ]
FIG. 8 shows a configuration diagram of still another example of the holographic optical recording medium according to the present invention. In the present embodiment, as shown in FIG. 8, a hologram recording layer 802 is sandwiched between two substrates 801 which are transparent to hologram recording light and servo light, and Servo markers 803 are provided on the surface of each of the substrates 801 opposite to the hologram recording layer 802.
[0038]
FIG. 9 is a diagram for explaining the principle at the time of recording and FIG. 10 is a diagram for explaining the principle at the time of reproduction when the holographic optical recording medium shown in FIG. 8 is used.
[0039]
9, reference numerals 901, 902, and 903 are the same as the substrate 801, the hologram recording layer 802, and the marker 803 in FIG. 8, respectively. 904 is reference light, 905 is object light, 906 and 907 are condenser lenses, and 908 is a recording area in the hologram recording layer 902 where a hologram is formed.
[0040]
The reference light 904 and the object light 905 are focused on the markers 903 on the respective back surfaces (that is, on the surface of the substrate 901 opposite to the incident surface) by the respective condenser lenses 906 and 907. Servo is applied. Servo laser light is superimposed on the optical path of the reference light 904 and the object light 905, and when the two condenser lenses 906 and 907 are simultaneously focused, the reference light 904 and the object light 905 are stored in the hologram recording layer 902. Irradiation is performed, and interference fringes formed thereby are recorded in a recording area 908 of the hologram recording layer 902.
[0041]
10, 1001, 1002, and 1003 are the same as the substrate 801, the hologram recording layer 802, and the marker 803 in FIG. 8, respectively. Reference numeral 1004 denotes a servo laser which is a light source for servo, 1005 denotes a half mirror which reflects a return beam for servo toward the position detector 1009, and 1006 denotes an object beam for recording the servo laser beam at the time of recording. (Which is cut off at the time of reproduction) and a half mirror for entering the condenser lens 1008, 1007 and 1008 are condenser lenses, and 1009 receives a return beam for servo, and And a position detector that determines the position of the servo laser beam incident on the holographic optical recording medium and feeds back the position information to the servo mechanism. Reference numeral 1010 denotes a recording area in which a hologram is formed in the hologram recording layer 1002; reference numeral 1011 denotes reference light for reproduction; reference numeral 1012 denotes reproduction light generated when the reference light 1011 enters the recording area 1010; Reference numeral 1013 denotes a reproduced image formed on the CCD imaging surface.
[0042]
At the time of reproduction, the object light is not irradiated, but the two condensing lenses 1007 and 1008 facing each other with the servo laser light are servo-controlled so that the marker 1003 corresponding to each of them is focused. When the two condenser lenses 1007 and 1008 are simultaneously focused, the reference beam 1011 is diffracted in the recording area 1010 of the hologram recording layer 1002 and becomes a reproduction beam 1012. (Real image). The reproduced image 1013 is an image pattern, which is converted into an electric signal by the CCD, subjected to a decoding process, and output as reproduced digital data.
[0043]
As in the present embodiment, the reference beam 904 and the object beam 905 are incident on the hologram recording layer 902 so as to face each other with the hologram recording layer 902 interposed therebetween. If an optical system in which the two lenses 906 and 907 are positioned symmetrically with the hologram recording layer 902 as the plane of symmetry is used, the effect of lens distortion during recording is canceled during reproduction. However, it is necessary to use an expensive lens that is not severe and has no distortion, but a general-purpose optical lens having a conventional distortion can be used in the present invention.
[Example 3 ]
FIG. 11 shows an embodiment. 2 In the holographic optical recording medium similar to the above, three examples are shown in which the relative relationship between the thicknesses of the two substrates is different. In the figure, 1101 is a reference light side substrate, 1102 is an object light side substrate, 1103 is a hologram recording layer, 1104 is a marker, and 1105 is a recording area in the hologram recording layer 1103 where a hologram is formed. It is.
[0044]
11A shows a case where the reference light side substrate 1101 is thinner than the object light side substrate 1102, FIG. 11B shows a case where the reference light side substrate 1101 is thicker than the object light side substrate 1102, and FIG. ) Shows a case where the reference light side substrate 1101 and the object light side substrate 1102 have the same thickness.
[0045]
In any of the above cases, holographic recording and reproduction were possible with good reproducibility.
[Example 4 ]
FIG. 12 shows an embodiment. 2 In the holographic optical recording medium similar to the above, examples are shown in which the positions of the markers are variously different. In the figure, reference numeral 1201 denotes a first substrate, 1202 denotes a second substrate, 1203 denotes a hologram recording layer, 1204 denotes a marker, and 1205 denotes a recording area in the hologram recording layer 1203 where a hologram is formed. It is.
[0046]
12A shows a case where the marker 1204 of the first substrate 1201 and the marker 1204 of the second substrate 1202 face each other with the hologram recording layer 1203 interposed therebetween, and FIG. 12B shows the case of FIG. Shows a case where the marker 1204 of the first substrate 1201 and the marker 1204 of the second substrate 1202 are shifted (positionally) in the direction along the hologram recording layer 1203, and (c) shows the first substrate 1201. Indicates that the marker 1204 is located at the interface between the first substrate 1201 and the hologram recording layer 1203, and the marker 1204 of the second substrate 1202 is located on the surface opposite to the hologram recording layer 1203. FIG. (E) shows a case where the marker 1204 is on both sides of the first substrate 1201, and (f) shows a case where the marker 1204 is on both sides of the second substrate 1202. The marker 1204 of the substrate 1201 and the holographic recording layer 1203 located on the opposite side, the marker 1204 of the second substrate 1202 shows a case at the interface between the substrate 1202 and the hologram recording layer 1203. Note that in the cases (d) and (e), the first substrate 1201 and the second substrate 1202 (neither include a marker) may be omitted.
[0047]
In all cases shown in FIG. 12, the shift width of the marker 1204 (exemplified in FIG. 12B) is smaller than the pitch of the marker 1204 (the distance between adjacent markers), and the entire holographic optical recording medium is If the thickness is smaller than the thickness, holographic recording and reproduction can be performed with good reproducibility.
[0048]
As described above, holographic recording / reproduction is performed while operating a servo mechanism using a holographic optical recording medium having a hologram recording layer and markers for servo and addressing during hologram recording and wavefront reproduction. As a result, recording and reproduction with good reproduction became possible. Therefore, even if the holographic optical recording medium according to the present invention is used as a replaceable holographic optical recording medium, it is possible to sufficiently cancel the position error due to the individual difference of the recording / reproducing system. It has become possible to provide a replaceable holographic optical recording medium.
[0049]
As the servo mechanism in the present invention, a servo mechanism similar to the servo mechanism in an optical disk device that is widely put into practical use can be used. In addition, as the marker capable of detecting the position by light in the present invention, a minute region having a refractive index different from the surroundings, a minute region having a different reflectance from the surroundings, and the like can be used in addition to the minute unevenness described above.
[0050]
Recording according to the present invention Equipment and In the reproducing apparatus, the wavelength of light used for hologram recording and the wavelength of light used for servo may be different. In particular, if the light used for the servo does not expose the photosensitive material used for the hologram recording, there is no need to consider the influence of the light used for the servo on the photosensitive material at the time of recording, which is convenient. Due to the chromatic aberration of the lens, the correlation between the position where the light used for hologram recording is focused and the position where the light used for servo is focused is slightly changed by the wavelength difference from the correlation when the wavelengths are equal. As long as adjacent holograms do not overlap, no trouble occurs.
[0051]
【The invention's effect】
Holographic optical recording medium capable of irradiating highly accurate reference light and object light by implementing the present invention And Information recording using the holographic optical recording medium And Record to play Equipment and A playback device can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a holographic optical recording medium according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram of a recording / reproducing apparatus according to the first embodiment of the present invention.
FIG. 3 is a diagram illustrating the principle of hologram recording according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating the principle of hologram reproduction in Embodiment 1 of the present invention.
FIG. 5 is a diagram showing a flow of a data recording process in the first embodiment of the present invention.
FIG. 6 is a diagram showing a flow of a data reproducing process according to the first embodiment of the present invention.
FIG. 7 Reference example 1 is a configuration diagram of a holographic optical recording medium in FIG.
FIG. 8 shows an embodiment of the present invention. 2 1 is a configuration diagram of a holographic optical recording medium in FIG.
FIG. 9 shows an embodiment of the present invention. 2 FIG. 4 is a diagram illustrating the principle of hologram recording in FIG.
FIG. 10 shows an embodiment of the present invention. 2 FIG. 4 is a diagram illustrating the principle of hologram reproduction in FIG.
FIG. 11 shows an embodiment of the present invention. 3 FIG. 4 is a diagram illustrating the principle of hologram recording and reproduction in FIG.
FIG. 12 shows an embodiment of the present invention. 4 FIG. 4 is a diagram illustrating the principle of hologram recording and reproduction in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Hologram recording layer, 3 ... Marker, 4 ... Track, 201 ... Holographic optical recording medium, 202 ... Servo laser, 203 ... Half mirror, 204 ... Half mirror, 205 ... Condensing lens, 206 ... Position detector, 207: recording / reproducing laser, 208: beam splitter, 209: object light, 210: reference light, 211: shutter, 212: beam expander, 213: spatial light modulator, 214: objective lens, 215 ... Reproduction lens, 216 CCD, 217 mirror, 301 substrate, 302 hologram recording layer, 303 marker, 304 reference light, 305 object light, 306 spatial light modulator, 307 objective lens, 308 Condensing lens, 309: recording area, 401: substrate, 402: hologram recording layer, 403: marker, 404: servo Laser, 405: half mirror, 406: half mirror, 407: condenser lens, 408: position detector, 409: recording area, 410: reference light, 411: objective lens, 412: reproduction lens, 413: reproduction image, 701: substrate, 702: hologram recording layer, 703: marker, 801: substrate, 802: hologram recording layer, 803: marker, 901: substrate, 902: hologram recording layer, 903: marker, 904: reference light, 905: object Light, 906: condenser lens, 907: condenser lens, 908: recording area, 1001: substrate, 1002: hologram recording layer, 1003: marker, 1004: laser for servo, 1005: half mirror, 1006: half mirror, 1007 ... Condenser lens, 1008 ... Condenser lens, 1009 ... Position detector, 1010 ... Recording area, 011: Reference light, 1012: Reproduced light, 1013: Reconstructed image, 1101: Reference light side substrate, 1102: Object light side substrate, 1103: Hologram recording layer, 1104: Marker, 1105: Recording area, 1201: First substrate Reference numeral 1202 denotes a second substrate, 1203 denotes a hologram recording layer, 1204 denotes a marker, and 1205 denotes a recording area.

Claims (6)

In a holographic optical recording medium having a substrate provided with a marker capable of position detection by light and a hologram recording layer provided on the substrate,
The marker is provided on the surface of the substrate opposite to the side on which the hologram recording layer is provided, so that the marker and the hologram recording layer are separated by a distance corresponding to the thickness of the substrate. A holographic optical recording medium comprising A holographic optical recording medium having two substrates and a hologram recording layer sandwiched between the two substrates,
At least one of the substrates is provided with a marker whose position can be detected by light,
The marker is provided on the surface of the substrate opposite to the side on which the hologram recording layer is provided, so that the marker and the hologram recording layer are separated by a distance corresponding to the thickness of the substrate. A holographic optical recording medium comprising The holographic optical recording medium according to claim 1, wherein the marker is a circular concave portion, a circular convex portion, a groove, or a linear convex portion. A means for recording a hologram on the hologram recording layer of the holographic optical recording medium according to any one of claims 1 to 3,
A recording device comprising: a servo mechanism that performs positioning of the object light during hologram recording by detecting the position of the marker light.
The object light at the time of the hologram recording and the light used for detecting the position of the marker have a configuration to focus on the marker through the same condensing lens,
A recording apparatus, wherein the object light and the light used for the position detection are not focused on the hologram recording layer. The recording device according to claim 4 ,
A recording apparatus, wherein the object light and the reference light at the time of recording the hologram are opposed to each other with the hologram recording layer interposed therebetween and are incident on the hologram recording layer. A means for reproducing a wavefront from a hologram recorded on the hologram recording layer of the holographic optical recording medium according to claim 1,
A servo mechanism that performs positioning of the reference light at the time of the wavefront reproduction by position detection using the light of the marker,
Reference light at the time of wavefront reproduction and light used to detect the position of the marker have a configuration in which the marker passes through the same condenser lens to focus on the marker,
A reproducing apparatus, wherein the reference light at the time of wavefront reproduction and the light used for the position detection are not focused on the hologram recording layer.

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