JP2007035176A - Optical recording medium and optical information recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium and optical information recording method by which hologram information can be accurately recorded at a prescribed position. <P>SOLUTION: The optical recording medium 1 is a medium of a shift multiple recording system provided with a hologram recording layer for recording an interference pattern between information light and reference light as information. The hologram recording layer and a tracking reflection layer are laminated in a control area 9, a test area 10 and a user area 11, and an address signal for accurately defining an irradiation position of the information light and the reference light is recorded beforehand on the tracking reflection layer. A recording condition is recorded beforehand as emboss pit information on the tracking reflection layer of the control area 9 by a medium manufacturer. The test area 10 is an area in which a reproduction output value is confirmed after performing multiple recording of a test signal on the hologram layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical recording medium and an optical information recording method, and in particular, irradiates an optical recording medium with two-dimensionally digitally modulated information light and a recording reference light, and interferes with an information recording layer of the optical recording medium. The present invention relates to an optical recording medium and an optical information recording method for recording information by the interference fringe pattern.

  Holographic recording, which records information on an optical recording medium using holography, superimposes information light with information and reference light inside the optical recording medium, and optical recording using the interference fringe pattern formed at that time as information. This is done by writing to the medium. When reproducing the recorded information, the information is reproduced by diffracting by the interference fringe pattern by irradiating the optical recording medium with the reference light.

  In this holographic recording, volume holography, particularly digital volume holography, has been developed in order to achieve an extremely high data density. Volume holography is a method of writing interference fringes three-dimensionally using the thickness direction of the optical recording medium, while digital volume holography is using the same optical recording medium and recording method as volume holography, The image information to be recorded is a recording method limited to a binary digital pattern. At the time of reproduction, the digital pattern information is read and decoded so that the original information is restored and displayed.

  An example of recording on an optical recording medium by volume holography is that the information light carrying information to be recorded and the recording reference light cause interference fringes in the thickness direction in the hologram recording layer of the optical recording medium. Information is recorded as a three-dimensional hologram by simultaneously irradiating from the transparent substrate side of the optical recording medium for a predetermined time and fixing the interference fringe pattern three-dimensionally in the hologram recording layer (for example, Patent Documents 1 and 2). 3 and Non-Patent Document 1).

  In holographic recording, as in a general optical recording apparatus, optical recording medium is irradiated with information light and recording reference light along a track while rotating the optical recording medium. Information is sequentially recorded as holograms at predetermined information recording positions in a plurality of information recording areas on the medium. In recording using such holography, it is desirable to use a practical semiconductor laser as a light source for information light and recording reference light, as in a general optical recording apparatus.

  Such volume holography is characterized in that the diffraction efficiency can be increased by increasing the thickness of the hologram recording layer of the optical recording medium, and the recording capacity can be dramatically increased by using multiple recording. Multiple recording is a method of irradiating information light and recording reference light for recording other information on an area in which information light and recording reference light have already been irradiated to record information. According to multiplex recording, a plurality of information can be recorded in the same irradiation area, and the data density is remarkably increased.

  In addition, when recording while rotating the optical recording medium, it is known that a shift multiplex recording system in which a part of the irradiation position on the optical recording medium is shifted and recorded while being recorded is effective as a multiplex recording system. . To explain this shift multiplex recording method, first, information light for recording the first information in the irradiation area a1 on an arbitrary track among the tracks on the optical recording medium indicated by the dotted line in FIG. The interference fringe pattern is recorded by irradiating the recording reference light.

  Next, as shown in FIG. 13B, the irradiation position is moved in the track tangential direction, and information light and recording reference for recording the next information in the irradiation area a2 partially overlapping with the irradiation area a1 are recorded. The interference fringe pattern is recorded by irradiating with light. In the same manner, recording is performed by shifting in the track tangential direction while overlapping a part of the irradiation position, and when the recording on the track that has started recording from the irradiation area a1 is full, the optical recording medium is then moved in the radial direction. Then, by repeating the recording on the adjacent track in the same manner as described above, as shown in FIG. 13C, the recording track starting at the irradiation area a1, the recording track starting at the irradiation area b1, and the recording starting at the irradiation area c1. A recording track starting from the track and the irradiation region d1 is sequentially formed, and information is holographically recorded.

  In this holographic recording, information light and reference light for recording are irradiated onto a hologram recording layer formed of a hologram recording material whose optical characteristics such as refractive index, dielectric constant, and reflectance change according to the intensity of the laser beam. This is done by fixing the interference fringe pattern. That is, a photochemical reaction is caused by the information light and the recording reference light in the hologram recording layer in the optical recording medium. For this reason, when the hologram recording layer is irradiated with information light and recording reference light to record information, the reaction product is consumed by the photochemical reaction and a product is generated. Therefore, the composition of the hologram recording layer in the irradiated region Changes before and after recording. As the composition of the hologram recording layer changes, the optimum intensity of the laser beam also changes.

  For this reason, as shown in FIG. 13, multiple recording records information by irradiating information light and recording reference light again to an area that has already been irradiated with information light and recording reference light. When a laser beam is used, the recording state of information becomes non-uniform depending on the multiplicity of the irradiated area (the number of times information is written on the irradiated area). Therefore, in multiple recording, it is preferable to change the intensity of the laser beam by adjusting the irradiation time and irradiation energy according to the composition of the irradiation region. The relationship between the composition change due to the laser beam irradiation and the optimum laser beam intensity in the composition can be obtained by experiments, but adjustment of the laser beam intensity requires complicated and complicated control. Met.

  In addition, depending on the material of the hologram recording layer, the reaction rate of the photochemical reaction is slow, so even when irradiated with information light and recording reference light, the interference fringe pattern is not fixed immediately, and it takes time to fix. There is a case. In such a hologram recording layer that requires time for fixing, irradiation with information light and recording reference light again before fixing affects the fixing of the interference fringe pattern in progress and has sufficient strength. This is the reason why the hologram cannot be recorded.

  In a general shift multiplex recording method, for example, the multiplicity in the circumferential direction (track tangential direction) of a disk-shaped optical recording medium for recording is m, and the number of rows in the radial direction (four rows in FIG. 13). In the case of n, in the multiplex recording in the circumferential direction, the overlapping degree of the irradiation area is different in the first m times, but the overlapping degree is the same in the subsequent irradiation area. I should have adjusted the strength. However, when moving to the next row in the radial direction, it is necessary to adjust the intensity of the laser beam again for the first m times, so that it is necessary to adjust the intensity of the laser beam m × n times. Further, in the conventional shift multiplex recording method, information cannot be continuously written to the hologram recording layer that requires time for fixing, and the writing time becomes long.

  Therefore, in order to address the above-described problem, Patent Document 1 discloses an optical information recording method that reduces the number of adjustments by collectively adjusting laser beams applied to the shift multiplex recording method in holographic recording. That is, in the conventional optical information recording method described in Patent Document 1, a plurality of first irradiation areas in the same state are irradiated with information light and recording reference light under a first condition to record a first information group. Then, the second information group is recorded by irradiating the plurality of second irradiation areas with the information light and the recording reference light under the second condition so as to overlap with the first irradiation area, and so on. This is a so-called surface multiplex recording system in which the operation is repeated, so that it is only necessary to adjust the irradiation condition m times in order to perform multiplex recording with a multiplicity of m, and the time until writing of the first information group is completed. Since the time for the photochemical reaction in each of the first irradiation regions can be set, continuous multiple recording can be performed.

  Further, Patent Document 2 discloses an optical recording medium in which servo areas for tracking servo and clock generation are discretely formed concentrically at predetermined intervals in the circumferential direction, and a hologram recording area is formed in a mirror area. Has been. Furthermore, in Patent Document 3, a hologram recording spot recorded on one track of the hologram recording area and a hologram recording spot recorded on a track adjacent to the hologram recording spot are recorded at different positions in the circumferential direction. Also, there is an optical information recording method in which recording is performed so that the pitch P between adjacent hologram recording spots is D / m, where D is the hologram recording spot diameter and m is the number of multiplexed hologram recording spots. It is disclosed.

JP 2005-32308 A JP 11-311938 A JP 2003-178456 A Horime et al., “A holographic medium close to take-off, realized 200 GB in 2006”, Nikkei Electronics, Nikkei BP, January 17, 2005, p. 105

  However, in the conventional optical information recording methods and optical recording media described in Patent Documents 1, 2, and 3, servo information is discrete and accurate position information and address information for each irradiation area cannot be obtained. It is difficult to accurately read the position of the hologram information to be recorded, and it is difficult to increase the recording density because the hologram information is recorded only in a portion where there is no servo information. Furthermore, in the conventional optical information recording method described in each of the above patent documents, it is not clear how to specify the optimum recording condition for each irradiation area to be multiplexed and recorded between a plurality of recording / reproducing apparatuses. Variations and compatibility are not considered.

  The present invention has been made in view of the above points, and an object thereof is to provide an optical recording medium and an optical information recording method capable of accurately recording hologram information at a predetermined position.

  Another object of the present invention is to provide an optical recording medium and an optical information recording method capable of improving the recording density of hologram recording information without restricting the hologram recording area.

  Furthermore, another object of the present invention is to provide an optical recording medium and an optical information recording method capable of uniformly recording holograms by reducing variations in the amount of reproduced light for each multiplicity, regardless of the recording order.

  In order to achieve the above object, according to the first invention, the irradiation area of the two-dimensionally digitally modulated information light having the first wavelength and the recording reference light is shifted while partially overlapping along the track. The shift multiple recording type optical recording medium includes a hologram recording layer that is sequentially irradiated and records an interference pattern between the information light and the recording reference light in the irradiation region of the information light and the recording reference light as information. Thus, a positioning signal and an address signal for assigning an address to each irradiation area and specifying the recording location accurately are recorded in advance on a tracking reflective layer that is different from the hologram recording layer in the depth direction. In this structure, the positioning signal and the address signal of the tracking reflective layer are reproduced by light having a second wavelength different from the first wavelength.

  In the present invention, the irradiation area of the information light and the recording reference light (that is, the hologram recording irradiation spot) on the shift multiplex recording optical recording medium can be accurately positioned based on the positioning signal, and The tracking reflection layer in which the positioning signal and the address signal are recorded and the hologram recording layer are separated in the depth direction of the optical recording medium, so that the recording position of the positioning signal and the address signal is not limited, Information hologram recording can be performed.

  In order to achieve the above object, according to the second aspect of the present invention, the irradiation area of the information light and the recording reference light is sequentially shifted so that the adjacent irradiation areas are in contact with each other along the track. After the irradiation area is shifted, the irradiation area is sequentially shifted so that a part of the irradiation area overlaps with the irradiation area one lap before the same track and the adjacent irradiation areas are in contact with each other. An optical recording medium in which the interference pattern between the information light and the recording reference light in the irradiation area is repeatedly recorded as information on the hologram recording layer by repeating a predetermined number of times, and indicates a number of times the irradiation area is superimposed per track. For each severity, the optimum light recording condition is recorded as embossed pit information on the tracking reflective layer in advance as medium manufacturing information.

  In general, the diffraction efficiency, which is an index of the amount of reproduced light, tends to gradually decrease as the number of times of irradiation of the information light and the recording reference light on the shift multiplex recording optical recording medium increases. In the invention, since the optimum light recording condition is recorded as emboss pit information in the tracking reflective layer as medium manufacturing information in advance for each multiplicity indicating the number of times of irradiation region superimposition per track, in the recording / reproducing apparatus, By reproducing the above light recording conditions, it is possible to easily obtain the optimum recording irradiation conditions.

In order to achieve the above object, according to a third aspect of the present invention, there is provided an irradiation area of information light and recording reference light having two-dimensionally digital modulation of the first wavelength, and an irradiation area adjacent to the track. Sequentially shifted so that they touch, and after shifting the irradiation area over one track, sequentially shifts so that a part of the same track overlaps the irradiation area one lap before and the adjacent irradiation area touches This is repeated for a predetermined number of times while shifting the irradiation area with respect to the same track, and the entire recording area is provided with a hologram recording layer that multiplex-records the interference pattern between the information light and the recording reference light in the irradiation area as information. An optical recording medium of a multiple recording method,
The recording area is pre-recorded in the tracking reflective layer having a depth different from that of the hologram recording layer as medium production information for each multiplicity indicating the number of times the irradiation area is superimposed per track. Based on the first area in which the final address and defect management information at the time of recording are automatically recorded on the hologram recording layer by the recording / reproducing apparatus, and the recording conditions reproduced from the first area in the recording / reproducing apparatus to be used A recorded test signal is multiplexed and recorded on the hologram recording layer, and a second area for obtaining optimum recording conditions based on an output value obtained by reproducing the recorded test signal, and a second area for multiplexing and recording user data on the hologram recording layer 3 regions.

  In the present invention, based on the recording condition reproduced from the first area, the recorded test signal is multiplexed and recorded on the hologram recording layer, and the optimum recording condition is obtained from the output value obtained by reproducing the recorded test signal. The second area is provided exclusively for the first area and the third area for multiplex recording of user data.

In order to achieve the above object, according to a fourth aspect of the present invention, there is provided an irradiation area of two-dimensionally digitally modulated information light having a first wavelength and recording reference light along a track on the optical recording medium. Shifting a part of the information light and the recording reference light in the irradiation area, and recording the interference pattern between the information light and the recording reference light as information on the hologram recording layer of the optical recording medium. In a multiple recording type optical information recording method,
First, an address is assigned to each irradiation area, and a positioning signal and an address signal for accurately specifying a recording location are recorded as emboss pit information on a tracking reflection layer that is different in the depth direction from the hologram recording layer. And positioning the irradiation area of the information light and the recording reference light based on the positioning signal obtained by reproducing from the tracking reflective layer with the light of the second wavelength different from the first wavelength, Information light in the irradiation region of the information light and the recording reference light is irradiated by sequentially irradiating the information light of the first wavelength and the recording reference light while sequentially shifting a part along the track on the optical recording medium. And a second step of recording the interference pattern of the recording reference light on the hologram recording layer of the optical recording medium as information.

  According to the present invention, the irradiation area (that is, the hologram recording irradiation spot) of the information light and the recording reference light on the shift multiplex recording optical recording medium can be accurately positioned based on the positioning signal.

  In order to achieve the above object, according to a fifth aspect of the present invention, the irradiation area of the information light and the recording reference light is sequentially shifted so that the adjacent irradiation areas are in contact with each other along the track. After the irradiation area is shifted, the irradiation area is sequentially shifted so that a part of the irradiation area overlaps with the irradiation area one lap before the same track and the adjacent irradiation areas are in contact with each other. An optical information recording method that repeats a predetermined number of times while shifting and multiplex-records an interference pattern between the information light and the recording reference light in the irradiation region as information on the hologram recording layer, and indicates a number of times the irradiation region is superimposed per track. For each severity, the optimum light recording condition is the medium manufacturing information as embossed pit information in the tracking reflective layer, and the third step recorded in advance before the second step recording. Characterized in that it comprises a flop.

  In order to achieve the above object, according to a sixth aspect of the present invention, there is provided an optimum light recording condition for each of a plurality of multiplicity levels recorded as embossed pit information in the tracking reflective layer according to the third step of the fifth aspect of the invention. Is only the optimum light recording condition for each of a plurality of representative multiplicity determined in advance among the predetermined number of multiplicity, and the optimum light recording condition for non-recorded multiplicity is recorded. The reproduction apparatus is characterized in that it is obtained by calculation from the optimum light recording conditions for each of a plurality of representative multiplicity levels reproduced from the tracking reflective layer. In the present invention, for all multiplicity, the optimum light recording condition for each multiplicity is not recorded, but only the optimum light recording condition for each typical multiplicity is recorded, and other multiplicity is recorded. Since the optimum light recording condition is obtained by calculation in the recording / reproducing apparatus, a relatively large user data recording area of the optical recording medium can be secured.

In order to achieve the above object, according to a seventh aspect of the present invention, the irradiation area of the two-dimensionally digitally modulated information light having the first wavelength and the recording reference light is adjacent along the track of the optical recording medium. After sequentially shifting the irradiation area to be in contact with each other and shifting the irradiation area over the entire track, a part of the same irradiation track is overlapped with the previous irradiation area and adjacent irradiation areas are in contact with each other. Is shifted a predetermined number of times while shifting the irradiation area with respect to the same track, and the interference pattern between the information light and the recording reference light in the irradiation area is recorded as information on the hologram recording layer of the optical recording medium. A multiple recording optical information recording method,
In the optical recording medium, for each multiplicity indicating the number of times the irradiation area is overlapped per track, an optimum light recording condition is recorded as medium manufacturing information with a different depth than the hologram recording layer in the first recording area. Holographic recording in a second recording area different from the first recording area based on the recording conditions pre-recorded in the reflective layer for reproduction and reproduced from the tracking reflective layer in the first recording area of the optical recording medium A first step of multiplexing and recording a test signal on the layer, and a second step of obtaining data of optimum recording conditions based on the reproduction output value of the test signal recorded on the hologram recording layer in the second recording area And a third step of recording data of the optimum recording condition obtained in the second step on the hologram recording layer in the first recording area.

  In the present invention, in the recording / reproducing apparatus, based on the recording condition reproduced from the tracking reflective layer in the first recording area, the test signal is multiplexed and reproduced, and based on the reproduction output value of the test signal, Since the optimum recording condition data is obtained and recorded in the hologram recording layer in the first recording area, the optimum recording condition data suitable for each recording / reproducing apparatus is stored in the hologram recording layer in the first recording area. After that, data of optimum recording conditions suitable for the recording / reproducing apparatus can be obtained immediately from the hologram recording layer in the first recording area without performing test recording and reproduction.

  According to the present invention, in holographic recording in which an interference pattern between a two-dimensionally modulated information beam and a recording reference beam is recorded as information on a hologram recording layer, each irradiation area is recorded in advance on an optical recording medium. By reproducing the positioning signal, the exact position of the irradiation area can be detected, so that compatibility between a plurality of recording / reproducing devices and optical recording media can be ensured, and the positioning signal and address signal are recorded. Since the tracking reflection layer and the hologram recording layer are separated in the depth direction of the optical recording medium, hologram recording can be performed without being restricted by the recording position of the positioning signal and the address signal. Information can be recorded on a hologram with higher density than in the past.

  In addition, according to the present invention, the optical recording medium manufacturer records the information (recording conditions) on the optimum recording energy of the superimposed recording information on the optical recording medium in advance for each multiplicity, thereby recommending each multiplicity. Since the recording energy information can be given to the recording / reproducing apparatus, it is possible to reduce the variation in the reproduction light amount (diffraction efficiency) for each multiplicity and make it uniform regardless of the recording order.

  Furthermore, according to the present invention, the optical recording medium manufacturer can record the optimum recording energy information of the superimposed recording information for each recording / reproducing apparatus based on the information previously recorded on the optical recording medium for each multiplicity. By testing the optimum recording energy, variations in the laser output between the recording / reproducing apparatuses can be absorbed, and more accurate and uniform hologram recording can be performed.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of an embodiment of an optical recording medium according to the present invention, and FIG. 2 is a schematic sectional view of an example of the optical recording medium of FIG. As shown in FIG. 1, the optical recording medium 1 of the present embodiment has a circular planar shape, and as shown in FIG. 2, the optical recording medium 1 has a cover layer from the surface side toward the substrate side. 2, a hologram recording layer 3, an adhesive layer 4, a wavelength selective reflection layer 5, a smooth layer 6, and a tracking reflection layer 7, which are stacked on a disk-shaped substrate 8 in this order.

  The tracking reflective layer 7 has a structure in which a metal reflective film such as aluminum is formed by sputtering or the like on a servo emboss pit array formed in a spiral shape or a concentric shape when viewed from the plane. The smoothing layer 6 is a layer that transmits the wavelength of the servo laser beam of at least 60% or more, preferably 90% or more, and is formed on the tracking reflection layer 7 by spin-coating an ultraviolet curable resin or the like.

  The wavelength selective reflection layer 5 selectively reflects 80% or more of the wavelength (for example, 400 nm) of a laser beam used for holographic recording and reproduction, and selectively transmits at least 60 for the servo laser beam (for example, wavelength 650 nm). % Or more, preferably 80% or more, for example, a reflective layer having a wavelength selective characteristic typified by a dichroic mirror made by laminating two kinds of dielectrics having different refractive indexes, and sputtering on the smooth layer 6. Is formed. The adhesive layer 4 is a layer made of a transparent pressure-sensitive adhesive sheet that adheres the hologram recording layer 3 to the wavelength selective reflection layer 5.

  The hologram recording layer 3 is formed of a hologram recording material whose optical properties such as refractive index, dielectric constant, and reflectance change according to the intensity of the laser beam when irradiated with a laser beam for a predetermined time. For example, Photopolymers HRF-600 (product name) manufactured by Dupont is used. The cover layer 2 provided on the hologram recording layer 3 is a circular transparent layer, and has an appropriate thickness of, for example, 0.6 mm or less. The hologram recording layer 3 has an appropriate thickness of, for example, 5 μm or more.

  Further, as shown in FIG. 1, the optical recording medium 1 has a spiral (spiral) track 12 formed from the inner periphery to the outer periphery, and has a control region 9 and a test region 10 in the present embodiment. (The track 12 may be formed concentrically). That is, a control area 9 composed of a predetermined number of spiral (spiral) tracks 12 is arranged on the innermost circumference of the optical recording medium 1. In the tracking reflective layer (7 in FIG. 2) in the control area 9, the recording conditions such as the physical information of the optical recording medium 1 and the optimum recommended recording power for each recording multiplicity are recorded by the medium manufacturer (medium manufacturer). Thus, as the emboss pit information is recorded in advance alternately with the address information as shown in FIG. 10, continuous address information is maintained. In the hologram recording layer (3 in FIG. 2) in the control area 9, the last address recorded every time the user uses and the defect management information for the defect are automatically recorded by the recording / reproducing apparatus.

  Further, the optical recording medium 1 is provided with a test area 10 including a predetermined number of spiral (spiral) tracks 12 adjacent to the outer peripheral side of the control area 9. This test area 10 takes into account variations such as laser power for each recording / reproducing apparatus, and reproduces the test signal after multiplex recording on the hologram layer based on the recording conditions reproduced from the control area 9 in each recording / reproducing apparatus. This is the area for checking the output value. Note that the test signal itself is not a special signal and may be a signal with a known signal level.

  As shown in FIG. 3A, the hologram information that is multiplexed and recorded has a remarkable tendency that the diffraction efficiency, which is an index of the reproduction light quantity, gradually decreases as the number of times the irradiation area is superimposed increases. As shown in FIG. 3B, the optimum recording energy differs for each number of superimpositions. Therefore, as described above, the tracking reflective layer (7 in FIG. 2) in the control area 9 has recording conditions such as physical information of the optical recording medium 1 and optimum recommended recording power for each recording multiplicity. Is recorded in advance as embossed pit information by a person (medium manufacturer). This recording condition is a typical recording condition obtained by a medium manufacturer using a predetermined recording / reproducing apparatus.

  Therefore, in order to obtain a recording condition suitable for each recording / reproducing apparatus, based on the recording condition reproduced from the tracking reflective layer in the control area 9, the test signal in the test area 10 is recorded on the hologram recording layer. Then, the reproduction of the test signal and the measurement of the reproduction output value are performed, and the optimum recording condition is obtained. The tracking reflective layer (7 in FIG. 2) in the test area 10 is provided with an address or the like at an emboss pit for each irradiation pitch Wp at the time of hologram recording in a spiral shape equivalent to the user area 11 described later.

  Further, the optical recording medium 1 is provided with a user area 11 including a preset number of spiral (spiral) tracks 12 adjacent to the outer peripheral side of the test area 10. The tracking reflective layer (7 in FIG. 2) in the user area 11 is provided with an address or the like in an embossed pit for each irradiation pitch Wp at the time of hologram recording in a spiral shape. In addition, user information is recorded as multi-bit page data in one irradiation on the hologram recording layer (7 in FIG. 2) in the user area 11, and corresponds to substitute data for defect data such as scratches as necessary. It is also possible to create a spare area.

  Next, an optical information recording / reproducing apparatus to which the optical information recording method according to the present invention is applied will be described. FIG. 4 shows a schematic configuration diagram of an example of an optical information recording / reproducing apparatus to which the optical information recording method according to the present invention is applied. 1, the optical recording medium 1 having the structure described with reference to FIGS. 1 and 2 is attached to a spindle 15 at the center, and is rotated by a spindle motor 16 based on a motor drive signal from an actuator driver 24.

  The optical pickup unit 17 is an optical device that irradiates the optical recording medium 1 with two-dimensionally digitally modulated information light and recording reference light, and is movable in the radial direction of the optical recording medium 1 by a feed motor 18. It is configured. As will be described later, the actuator driver 24 is controlled based on the output signal of the servo circuit 23. As a result, the position of the objective lens in the optical pickup unit 17 is controlled, so that tracking control and focus control are possible. It is made into the composition.

  First, recording preparation will be described. For example, when the optical recording medium 1 is loaded in the apparatus, the optical pickup unit 17 first obtains a drive signal from the actuator driver 24 and is moved to the innermost peripheral region of the optical recording medium 1 by the feed motor 18. Thereafter, the actuator driver 24 performs a focusing operation on the tracking reflective layer 7 of the optical recording medium 1 by a method such as a general astigmatism method, and the focus is adjusted. The tracking operation is performed by such a method.

  Thereby, the optical pickup unit 17 irradiates the tracking reflection layer 7 in the control area 9 of the optical recording medium 1 with a laser beam, and the optical pickup unit 17 receives the reflected light of the irradiated laser beam and photoelectrically converts it. Thus, the physical data such as medium characteristics recorded by the medium manufacturer and the optimum recording energy data such as recommended recording power are read out by the emboss pits in the tracking reflective layer 7, and then the hologram recording layer in the control area 9 is also used. 3 is irradiated with a laser beam, and the optical pickup unit 17 receives and photoelectrically converts the reflected light of the irradiated laser beam, whereby the recording management recorded on the hologram recording layer 3 in the control area 9 by the recording / reproducing apparatus. Read information (defect management information) To collect the information of the medium 1.

  When the mounted optical recording medium 1 is the first optical recording medium mounted to the recording / reproducing apparatus, each of several types of multiplicity based on the information recorded in the control area 9 of the optical recording medium 1 next. Is repeated several times to confirm the optimum recording energy. Thereafter, the optimum recording condition in the recording / reproducing apparatus obtained by the recording energy based on the information is recorded on the hologram layer 3 in the control area 9 to complete the recording preparation.

  FIG. 5 shows a configuration diagram of an example of the optical pickup unit 17. As shown in the figure, the optical pickup unit 17 includes a light source 31 for generating a laser beam for information recording and reproduction, and a servo light source 40. As the light source 31 for generating a laser beam for information recording and the light source 40 for servo, a semiconductor laser is used in the same manner as a light source in a general recording apparatus that records information on a disk-shaped optical recording medium. When recording information on the hologram recording layer 3 of the optical recording medium 1, the information signal to be recorded output from the signal processing circuit 21 of FIG. 4 drives the light source 31 of FIG. 5 via the laser driver 22. .

  The holographic recording laser beam emitted from the light source 31 is collimated by a collimator lens 32 and then irradiated to a spatial light modulator (SLM) 33. In order to record in the SLM 33, for example, two-dimensional information such as a QR code and a reference light pattern are arranged on the outer periphery thereof. The SLM 33 may be a transmissive type, but here a reflective type is used. As a typical reflective SLM, for example, D-ILA (registered trademark) manufactured by Victor Company of Japan, which is a reflective liquid crystal element, can be cited. Information light and reference light of the same wavelength that are two-dimensionally digitally modulated by spatial light modulation in the SLM 33 are transmitted through a polarization beam splitter (PBS) 34 and incident on a dichroic beam splitter 37.

  On the other hand, a servo laser beam having a wavelength different from that of the information light and the reference light is emitted from the servo light source 40, converted into parallel light by the collimator lens 41, and then transmitted through the polarization beam splitter (PBS) 42. The light enters the dichroic beam splitter 37. Thereby, in the dichroic beam splitter 37, the information light and the reference light are wavelength-combined with the servo laser beam, converted into circularly polarized light by the quarter wavelength plate 38, and condensed by the objective lens 39. The optical recording medium 1 is irradiated. Of the light irradiated to the optical recording medium 1, the information light and the reference light are reflected by the wavelength selective reflection layer 5 of FIG. 2, and the hologram recording layer 3 shows an interference pattern between the information light and the reference light. Generated and recorded as information.

  Further, the servo laser beam passes through the hologram recording layer 3 and the wavelength selective reflection layer 5 of FIG. 2 in order, enters the tracking reflective layer 7 and is reflected, and the reflected light is reflected by the wavelength selective reflection layer 5. Then, the light passes through the hologram recording layer 3 sequentially and enters the objective lens 39. The reflected light incident on the objective lens 39 in FIG. 5 is transmitted through the objective lens 39, converted from circularly polarized light to linearly polarized light by the quarter wavelength plate 38, reflected by the dichroic beam splitter 37, and further reflected by the PBS 42. It is received by the photodetector 43 and subjected to photoelectric conversion. The electrical signal output from the photodetector 43 is supplied to the focus error control unit 44, the tracking error control unit 45, and the address signal reproduction unit 46, and is converted into a focus error signal, a tracking error signal, and an address signal.

  The servo circuit 23 in FIG. 4 includes the focus error control unit 44 and the tracking error control unit 45 in FIG. 5, and output signals thereof are supplied to the actuator driver 24 to rotate the spindle motor 16 and the feed motor 18. The position of the objective lens 39 in the optical pickup unit 17 is variably controlled. 4 includes the photodetectors 35 and 43 shown in FIG. The address signal reproduced by the address signal reproducing unit 46 is supplied to the signal processing circuit 21 shown in FIG. The address signal reproducing unit 46 is not only an address signal indicated by an ID in FIG. 10A to be described later, but also a detection signal of the synchronization signal Sync, and a medium manufacture recorded in advance by the optical recording medium manufacturer instead of the ID. Information is also reproduced and input to the CPU 20 and the signal processing circuit 21 of FIG.

  Next, the optical path during reproduction will be described. A holographic reproducing laser having a constant light intensity is emitted from the light source 31 of FIG. 5, is converted into parallel light through the collimator lens 32, and is irradiated to the SLM 33 to which only reference light information is sent. The laser beam of the reference light that has been spatially modulated by the SLM 33 passes through the PBS 34 and enters the dichroic beam splitter 37, where it is wavelength-combined with the servo laser beam, and further passes through the quarter wavelength plate 38 and becomes circularly polarized light. After that, the light is condensed by the objective lens 39 and irradiated onto the optical recording medium 1. The reference light enters the hologram recording layer 3 and is reflected light having an intensity corresponding to the interference fringes of the hologram recording layer 3.

  The reflected light (returned light) passes through the objective lens 39 as a holographic laser beam and is converted into linearly polarized light having a phase difference of 90 degrees with respect to the incident light by the quarter wavelength plate 38, and then the dichroic beam splitter. 37, the wavelength of the reflected laser beam is separated from the reflected light of the servo laser beam, and the holographic laser beam passes through the dichroic beam splitter 37 and enters the PBS 34, where it is reflected and received by the photodetector 35 for photoelectric conversion. Is done. Like the photodetector 43, the photodetector 35 is composed of a CCD (charge coupled device), a C-MOS, or the like. The readout signal obtained by photoelectrically converting the holographic laser beam is converted into the signal shown in FIG. This is supplied to the processing circuit 21 and the CPU 20.

  Further, the servo laser beam is reflected by the dichroic beam splitter 37 and incident on the PBS 42, reflected there, received by the photodetector 43 and subjected to photoelectric conversion, and the obtained electrical signal is a focus error control unit 44. The tracking error control unit 45 and the address signal reproduction unit 46 are supplied. The signal processing circuit 21 in FIG. 4 reads the address information from the address signal reproduction unit 46 in FIG. 5, reads the exact position of the optical pickup unit 17 on the optical recording medium 1 based on this, and sends the address information to the CPU 20. send. The CPU 20 compares the address designated for recording or reproduction with the current reproduction address input from the signal processing circuit 21 and calculates the movement amount of the optical pickup unit 17.

  At the time of hologram recording, based on the address information sent from the CPU 20, the optical pickup unit 17 is moved to the designated address of the optical recording medium 1 using the feed motor 18 and the like using the actuator driver 24 and the servo circuit 23. Move to position. At this time, the CPU 20 confirms the position after the movement of the optical pickup unit 17 by an address signal from the emboss pit of the tracking reflective layer 7 of the optical recording medium 1 with the laser beam emitted from the servo light source 40. Two-dimensional information to be recorded is displayed on the SLM 33, and a laser beam for hologram recording with an optimum recording energy is emitted from the light source 31 through the laser driver 22 in accordance with the multiplicity confirmed in advance, and optical recording is performed through the optical system. Information is recorded on the hologram recording layer 3 of the medium 1.

  The information recording sequence starts from the recording for confirming the optimum recording energy based on the multiplicity, and after the optimum recording energy in the recording / reproducing apparatus is determined, the information is recorded in the control area 9 and the user area 11 of the optical recording medium 1 in FIG. Finally, recording information indicating which address is recorded from which address and at what multiplicity is converted from the CPU 20 into two-dimensional information and sent to the SLM 33 to be recorded as hologram information on the hologram recording layer 3 in the control area 9. Then, the recording operation ends.

  Next, at the time of hologram reproduction, based on the address information sent from the CPU 20 in FIG. 4, an optical pickup is used by using the feed motor 18 and the like using the actuator driver 24 and the servo circuit 23 as in the case of hologram recording. The unit 17 is moved to the designated address position of the optical recording medium 1 and the optical pickup unit 17 is moved to reflect the tracking reflection of the optical recording medium 1 by the laser beam emitted from the servo light source 40 by the CPU 20. This is confirmed by an address signal from the emboss pit of layer 7.

  After that, the CPU 20 emits the same laser beam as the hologram recording from the light source 31 as a reproducing laser beam with a lower output of 1/10 or less than that at the time of recording. This reproduction laser beam passes through an optical system equivalent to the recording laser beam at the time of hologram recording, but the information on the SLM 33 is only the reference light recorded on the hologram and no information light. As described above, during reproduction, reflected light corresponding to the interference fringes recorded on the hologram recording layer 3 of the optical recording medium 1 is transmitted to the PBS 34 via the objective lens 39, the quarter wavelength plate 38, and the dichroic beam splitter 37. The reflected light reflected by the incident light is converted by the photodetector 35 into two-dimensional information into an electric signal and sent to the signal processing circuit 21 in FIG.

  Next, the recording information and irradiation pattern of the optical recording medium according to the embodiment of the optical information recording method of the present invention will be described in more detail. In the present embodiment, for the hologram recording layer 3 of the optical recording medium 1 composed of a material whose fixing time is shorter than the recording time, information light and reference light are recorded in FIG. As indicated by 51-1, a spot having a diameter DSP of 500 μm is formed, and interference fringes are generated in the hologram recording layer 3 to perform recording, and subsequently, moved by 500 μm in the track tangential direction (circumferential direction). As indicated by 51-2 in FIG. 5A, a spot having a diameter DSP of 500 μm is formed and interference fringes are generated in the hologram recording layer 3 for recording. Record every 500 μm. Therefore, recording is performed so that adjacent spots are in contact with each other without being superimposed.

  When the above operation is repeated and recording for one round of the track is performed for each irradiation area indicated by a1, a2,..., Am in FIG. 7 (A), then, FIG. As shown in the figure, a spot 52-1 is formed at a position substantially overlapping with the spot 51-1 formed one track ahead by shifting the pitch Wp (for example, 10 μm) in the track tangential direction (circumferential direction) of the same track, Interference fringes due to information light and reference light are generated in the hologram recording layer 3 for recording, and thereafter, spiral tracks are recorded every 500 μm. That is, the first recording of the number of times of superposition is performed so that the irradiation spot of the information light and the reference light after one track is shifted by the pitch Wp with respect to the irradiation spot before one track.

  When the above operation is repeated and recording for one round of the track composed of each irradiation area indicated by a1 ′, a2 ′,..., Am ′ in FIG. In the (circumferential direction), a spot is formed that overlaps the spot 52-1 of FIG. 6B formed one track before by shifting by a pitch Wp (for example, 10 μm), and the information light and the reference light are used. Interference fringes are generated in the hologram recording layer 3 to perform hologram recording, and similarly, spots are formed on the spiral track every 500 μm and recording is performed for the second time.

  Thereafter, when this operation is repeated and the recording of a predetermined multiple recording number (N = DSP / Wp) is completed for one track, the radius of the optical recording medium with respect to the spot 51-1, as shown in FIG. Moving in the direction by Wp, a spot 61-1 that largely overlaps the spot 51-1 is formed, and multiplex recording on one track similar to the above is started again.

  As shown in FIG. 9 instead of FIG. 8, the spot 51-1 moves in the radial direction of the optical recording medium by the spot diameter DSP to form a spot 62-1 in contact with the spot 51-1. Then, multiple recording on one track similar to the above may be started again.

  Here, in the present embodiment, the positioning signal for determining the spot center position of the hologram irradiation spot such as the spots 51-1, 51-2, 52-1, 61-1, 62-1 is the above-mentioned. The optical recording medium 1 is characterized in that it is recorded in advance as an embossed pit row on the tracking reflective layer 7 in the control area 9, test area 10 and user area 11.

  FIG. 10A shows an embodiment of a signal format such as an address signal in the control area recorded on the tracking reflective layer 7 described above. As shown in FIG. 10 (A), the address signal and the like in the control area 9 are recorded with a length of 500 μm, which is the same as the diameter DSP of the hologram recording irradiation spot, and each sector has a hologram recording irradiation spot. The first signal part composed of the marker M, ID and the synchronization signal Sync, and the second signal part composed of the control data C and the synchronization signal Sync, each having a pitch Wp (= 10 μm) unit length, are alternately arranged. It has been configured.

  Here, the synchronization signal Sync is a positioning signal for determining the spot center position of the hologram irradiation spot. The ID is an address signal indicating address number information. The control data C indicates recording conditions such as the physical information of the optical recording medium 1 and the optimum recommended recording power for each recording multiplicity recorded in advance by measurement by a medium manufacturer (medium manufacturer). It is data.

  As an example of a pit row for performing specific tracking, as shown in FIG. 10B, a period of 1T = 0.133 μm, which is the same as that of a known DVD (Digital Versatile Disc), is basically used. (Where T is the period of the channel clock). The basic structure of the pit train is a combination of 3T signal to 11T signal that is a reference for clock generation, marker M arranged just before the ID portion where the address is written, and D8-16 modulation to maintain the clock signal 4 bytes of address signal part (ID), synchronization signal Sync for defining the actual recording spot center, and control data C.

  It is possible to add 1-byte ECC (error check code) to the 4 bytes of the address signal part ID in order to increase reliability. Even if a read error occurs, correction is made possible by providing, for example, continuity in the address assignment method in the track in one round. Note that it is desirable that the synchronization signal Sync and the signal of the marker M have a pattern that does not occur in the ID or control data C.

  FIG. 10C shows the change in the reflectance of FIG. 10B and the voltage of the address signal as a servo signal. Servo light is diffracted at the pit portion, the amount of reflection decreases, and the voltage level decreases. As shown in FIG. 10C, the amplitude of the 3T signal of the shortest mark is slightly reduced due to the MTF (Modulation Transfer Function), but it is set to a value that is not problematic for binarization. A clock signal is generated by being locked by a well-known phase-locked loop (PLL) circuit in the optical recording medium recording / reproducing apparatus. Also, information is decoded using the edge of the signal, and in this example, the falling edge center portion of 5T Sync is set to the spot center position of the hologram irradiation spot.

  FIG. 11A similarly shows an embodiment of a signal format such as an address signal of the user area 11 recorded on the tracking reflective layer 7. The address signal recorded on the tracking reflecting layer 7 in the user area 11 is recorded with a length of 500 μm, which is the same as the diameter DSP of the hologram recording irradiation spot, and each sector has a hologram recording irradiation spot pitch. The point of the length in units of Wp (= 10 μm) is the same as the address signal and the like recorded in the control area 9, but the control data C does not exist as shown in FIG. , An ID and a sync signal sync. A signal string such as an address signal of the user area 11 is shown in FIG. 11B, and a signal waveform is shown in FIG.

  In order to define the actual position of hologram recording, a synchronization signal Sync is arranged immediately after the ID signal so that the laser beam of the hologram recording is irradiated when the Sync falls or rises. When the diameter DSP of the hologram irradiation spot of the hologram recording is 500 μm, first, a sector is provided every 0.5 mm as a length that is not multiplexed in the circumferential direction. If the hologram irradiation spot pitch Wp is multiplexed every 10 μm, DSP / Wp = 50 pieces of information data are hologram-recorded in one sector.

  For this reason, in this embodiment, the synchronization signal Sync is input every 10 μm which is the hologram irradiation spot pitch Wp, and the jitter of the embossed pits is reduced to 8% or less, which is about the same level as DVD, by the tracking reflective layer 7. The hologram recording irradiation position can be controlled in the track circumferential direction with an accuracy of 01 μm or less.

  In the radial direction of the optical recording medium 1, it is desirable that the pitch of the embossed pit rows of the tracking reflective layer 7 is 1/10 or less of the irradiation pitch Wp at the time of hologram recording. For example, when the radial pitch is the same as the irradiation pitch Wp of 10 μm at the time of hologram recording in the circumferential direction, the tracking pitch of the tracking reflective layer 7 is 1 μm or less.

  The tracking reflective layer 7 in the control area 9 has a first signal in the format shown in FIG. 10A and the physical information of the optical recording medium and the hologram instead of the ID of the first signal. The second signal in which the medium manufacturing information previously obtained by the medium manufacturer such as the optimum laser beam irradiation condition for each number of times of the recording irradiation spot (irradiation area) is superimposed alternately with a predetermined sector period, for example. Are recorded as address signals. On the other hand, only the first signal of the format shown in FIG. 10A is continuously recorded as an address signal in the tracking reflective layer 7 in the test area 10 or the user area 11.

  Thus, in the present embodiment, the hologram recording irradiation spot for hologram recording is accurately determined from the reproduction position of the synchronization signal Sync in the address signal reproduced from the tracking reflection layer 7 of the optical recording medium 1 by the servo laser beam. Therefore, compatibility between a plurality of recording / reproducing apparatuses and the optical recording medium 1 can be ensured.

  The servo laser beam for reproducing the tracking reflective layer 7 and the laser beam of information light and reference light for performing hologram recording on the hologram recording layer 3 have different wavelengths, and the tracking reflective layer 7 and the hologram Since it is separated from the recording layer 3 in the depth direction of the optical recording medium 1, hologram recording can be performed without being restricted by the recording position of the address signal, and the information signal has a higher density hologram than before. Can be recorded.

  In the present embodiment, the laser beam irradiation area of the information beam and the reference beam for hologram recording on the hologram recording layer 3 of the optical recording medium 1 is partially or partially overlapped with the track tangential direction (circumferential). In the shift multiple recording method in the circumferential direction for recording while shifting in the direction), from the control layer 9 in which the information of the optimum recording energy is recorded in advance by the optical recording medium manufacturer for each multiplicity (number of superpositions) of the irradiation area Optimal recording energy is reproduced, and based on information on the optimum recording energy for each multiplexing ratio, regardless of the recording order, variation in reproduction light quantity (reproduction efficiency) can be reduced for each multiplicity, and hologram recording can be performed uniformly. .

  Furthermore, the optimum recording energy is reproduced from the control layer 9 in which the information of the optimum recording energy is recorded in advance by the optical recording medium manufacturer for each multiplicity of the irradiation area. Since the optimum recording energy can be tested using the test area 10 of the optical recording medium 1, the variation in the laser power of the recording laser beam between the recording and reproducing apparatuses is absorbed, and the hologram is more accurately and uniformly obtained. Can be recorded.

  Furthermore, when recording the laser beam irradiation area of the information beam and the reference beam while partially overlapping or shifting in the track tangential direction (circumferential direction) without overlapping, the number of times the irradiation area is superimposed on the same track (a large number of times) Information on the optimum recording energy corresponding to the severity) is recorded in the control area 9 of the optical recording medium 1, so that the hologram recording layer 3 is an optical recording medium composed of a material whose fixing time is shorter than the recording time. Based on the information of the optimum recording energy corresponding to the number of times of superimposition (multiplicity) of the irradiation areas reproduced from the control area 9, it is possible to cope with multiple recording in which the irradiation areas overlap.

  Thus, in the circumferential shift multiplex recording method of the present invention, the laser power for hologram recording is based on the information of the optimum recording energy corresponding to the number of times of superimposition (multiplicity) of the irradiation area reproduced from the control area 9. Since the optimum hologram recording corresponding to the number of times of irradiation (irradiation spot) superimposition (multiplicity) can be performed, it is possible to collectively adjust the intensity of the laser beam in accordance with the composition of the irradiation region and reduce the number of adjustments. Can be controlled easily.

  For example, if the multiplicity in the circumferential direction is m and the number of rows in the radial direction is n, the multiplicity in the radial direction is x (x ≦ n). Although adjustment was necessary, in the present invention, it is sufficient to adjust the intensity of the laser beam m × x times. Further, the time required to complete the writing of the information signal in one track of the optical recording medium 1 is the time for the photochemical reaction in each irradiation region indicated by a1, a2,..., Am in FIG. Therefore, in this embodiment, the multiple recording method can be executed continuously.

  Note that the optimum recording power of the irradiation spot (irradiation area) after the second track for the same track indicated by 52-1 in FIG. 6B and a1 ′ in FIG. 7B is one track before the track. The amount of reactant in the hologram recording layer 3 is determined by the ratio (multiplicity) of superimposing with the irradiation spots (irradiation regions) 51-1, a1, and the like. Therefore, strong irradiation intensity is required. That is, as shown in FIG. 3B, the optimum recording energy of the irradiation area per track circumference needs to be increased as the number of times the irradiation area is overlapped on the same track increases (as the multiplicity increases), Therefore, it is desirable that there is prior information on the optimum recording energy for the number of combinations of the multiplicity.

  However, as shown in FIG. 3B, since the multiplicity of five or more multiplexes tends to be linear to some extent, the test recording of the optimum recording energy in a plurality of multiplicity is not necessarily performed for all combinations of multiplicity. There is no need to do it. Therefore, the tracking reflection layer 7 in the control region 9 of the optical recording medium 1 according to the present embodiment has, for example, a superimposition number (multiplicity) of 0, 1, 2, 3, 4, 4, 5 times. The optimum recording energy for each of 10, 20 times,..., Maximum times is recorded, and the number of superimpositions (multiplicity) indicated by a dotted line I in FIG. Information is recorded, and the optimum recording energy of multiplicity other than the above can be obtained by calculation from the information of the inclination characteristics.

  The conventional optical information recording method described in Patent Document 1 is characterized in that the optical recording medium is divided into a plurality of zones and each information group is recorded in each zone. As is well known, recording is performed by dividing a disk-shaped recording medium into a plurality of zones. As is well known, the ZCAV (Zone Constant Angular Velocity) method in which the angular velocity is constant in each zone, or the linear velocity is constant in each zone. ZCLV (Zone Constant Linear Velocity) method is known, and the above-described conventional optical information recording method applies these ZCAV method and ZCLV method.

  However, when holographic recording is performed by the CAV method in which the recording medium is rotated at a constant angular velocity without being divided into ZCAV methods or zones, the irradiation area is determined as shown in FIG. 12, and the ZCAV method or the CAV method with a constant angular velocity is determined. However, it is difficult to optimize the recording energy because the linear velocity continuously changes depending on the radius of the optical recording medium. In the ZCLV method, the change in the rotation speed of the optical recording medium can be kept within a certain range, and the angular velocity and linear velocity of the optical recording medium can be made constant by dividing each zone. Therefore, the ZCLV method having a large number of zones is not desirable because the number of combinations of test recordings with optimum recording energy increases.

  Therefore, in the present invention, by adopting the CLV method over the entire surface of the optical recording medium, one type of recording linear velocity can be achieved, and recording is performed with the minimum combination of test recordings of optimum recording energy.

  Note that the present invention is not limited to the above embodiment, and the present invention includes a computer program executed by the CPU 20 shown in FIG. 4 and having the function of the signal processing circuit 21. The computer program may be recorded on a recording medium and taken into the computer from the recording medium, or distributed via a communication network and taken into the computer, and further stored in dedicated hardware. And may be incorporated in the computer.

1 is a plan view of an embodiment of an optical recording medium of the present invention. It is a schematic sectional drawing of an example of the optical recording medium of FIG. FIG. 6 is a characteristic diagram showing an example of the relationship between the number of superpositions (multiplicity) and diffraction efficiency, and a characteristic diagram showing an example of the relationship between the number of superpositions (multiplicity) and the optimum recording energy. It is a schematic block diagram of an example of the optical information recording / reproducing apparatus to which the method of this invention is applied. It is a block diagram of an example of the optical pick-up unit in FIG. It is explanatory drawing of an example of the multiplex recording of the track direction of the hologram recording by the method of this invention. It is explanatory drawing of an example of the multiple recording of the medium radial direction of the hologram recording by this invention. It is explanatory drawing of an example of the multiplex recording of the radial direction of the hologram recording by the method of this invention. It is explanatory drawing of the other example of the multiplex recording of the radial direction of the hologram recording by the method of this invention. It is a figure explaining the format etc. of one Embodiment of the address signal etc. of the control area recorded by the method of this invention. It is a figure explaining the format etc. of one Embodiment of the user area address signal etc. which are recorded by the method of the present invention. It is explanatory drawing of the example of the multiplex recording of an example of the radial direction of the conventional optical information recording method. It is explanatory drawing of an example of the multiplex recording of the conventional optical information recording method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical recording medium 2 Cover layer 3 Hologram recording layer 4 Adhesive layer 5 Wavelength selective reflection layer 6 Smooth layer 7 Tracking reflection layer 8 Substrate 9 Control area 10 Test area 11 User area 12 Track 17 Optical pickup unit 20 Central processing unit (CPU) )
31 Light source for recording / reproduction 33 Spatial light modulator (SLM)
34, 42 Polarizing beam splitter (PBS)
35, 43 Photo detector 37 Dichroic beam splitter 38 1/4 wavelength plate 39 Objective lens 40 Light source for servo

Claims (7)

The irradiation area of the two-dimensionally digitally modulated information light and the recording reference light having the first wavelength is sequentially irradiated while being partially overlapped along the track, and the information light and the recording reference light are irradiated. An optical recording medium (1) of a shift multiplex recording system comprising a hologram recording layer (3) for recording as an information an interference pattern between the information light and the recording reference light in the irradiation area of
An address is assigned to each irradiation area, and a positioning signal and an address signal for accurately specifying a recording location are recorded in advance in the tracking reflection layer (7) different from the hologram recording layer in the depth direction, An optical recording medium having a structure in which a positioning signal and an address signal of the tracking reflective layer are reproduced by light having a second wavelength different from the first wavelength. The irradiation area of the information light and the recording reference light is sequentially shifted so that adjacent irradiation areas are in contact with each other along the track. It is repeated a predetermined number of times while shifting the irradiation area with respect to the same track, so that the irradiation area is partially overlapped with the irradiation area before the circumference and the adjacent irradiation areas are in contact with each other. An optical recording medium in which an interference pattern between information light and the recording reference light is multiplexed and recorded on the hologram recording layer as information,
An optimum light recording condition is recorded in advance as emboss pit information on the tracking reflective layer as medium manufacturing information for each multiplicity indicating the number of times the irradiation area is overlapped per track. Item 5. The optical recording medium according to Item 1. The irradiation area of the two-dimensionally digitally modulated information beam having the first wavelength and the recording reference beam is sequentially shifted so that adjacent irradiation areas are in contact with each other along the track, and the irradiation is performed over the entire track. After the area is shifted, the irradiation area is sequentially shifted so that a part of the irradiation area one lap before the same track overlaps the adjacent irradiation area and the adjacent irradiation area is in contact with the same track. An optical recording medium of a shift multiplex recording system (1) which has a hologram recording layer that multiplex-records on the entire surface of the recording area by repeatedly recording the interference pattern between the information light and the recording reference light in the irradiation area as information. ) And
The recording area is
For each multiplicity indicating the number of times the irradiation area is overlapped per track, an optimal light recording condition is recorded in advance on the tracking reflective layer having a depth different from that of the hologram recording layer as medium manufacturing information, and A first area (9) in which a final address and defect management information at the time of recording by a recording / reproducing apparatus are automatically recorded on the hologram recording layer;
In the recording / reproducing apparatus to be used, a test signal recorded based on the recording condition reproduced from the first area is multiplex-recorded on the hologram recording layer, and an optimum recording condition is determined by an output value obtained by reproducing the recorded test signal. A second area (10) for seeking;
3. The optical recording medium according to claim 1, further comprising: a third area for recording user data on the hologram recording layer. The irradiation area of the two-dimensionally digitally modulated information light of the first wavelength and the recording reference light is sequentially irradiated while being partially shifted along the track on the optical recording medium (1), Optical information recording of a shift multiplex recording system in which an interference pattern between the information light and the recording reference light in the irradiation region of the information light and the recording reference light is recorded on the hologram recording layer (3) of the optical recording medium as information. In the method
An embossing pit information is provided on the tracking reflection layer (7), which is different in the depth direction from the hologram recording layer, by assigning an address to each irradiation area and accurately specifying a recording location and an address signal. A first step of recording as:
While positioning the irradiation area of the information light and the recording reference light based on the address signal obtained by reproducing from the tracking reflective layer with the light of the second wavelength different from the first wavelength, The information light and the recording reference light of the first wavelength are sequentially irradiated while being partially overlapped along the track on the optical recording medium, and the information light and the reference light for irradiation are irradiated. A second step of recording an interference pattern between the information light and the recording reference light as information on a hologram recording layer of the optical recording medium. The irradiation area of the information light and the recording reference light is sequentially shifted so that adjacent irradiation areas are in contact with each other along the track. It is repeated a predetermined number of times while shifting the irradiation area with respect to the same track, so that the irradiation area is partially overlapped with the irradiation area before the circumference and the adjacent irradiation areas are in contact with each other. An optical information recording method for performing multiple recording on the hologram recording layer as information on an interference pattern between information light and the recording reference light,
For each multiplicity indicating the number of times the irradiation area is overlapped per track, an optimum light recording condition is preliminarily recorded as medium manufacturing information as embossed pit information in the tracking reflective layer before recording in the second step. 5. The optical information recording method according to claim 4, further comprising a third step of recording.   The optimum light recording conditions for each of the plurality of multiplicityes recorded as the embossed pit information in the tracking reflective layer in the third step are a plurality of predetermined representatives of the predetermined multiplicity. For the optimum light recording conditions of each multiplicity of light, and for the optimum light recording conditions of non-recorded multiplicity, the plurality of representatives reproduced from the tracking reflective layer in the recording / reproducing apparatus 6. The optical information recording method according to claim 5, wherein the optical information recording method is calculated from the optimum light recording conditions of each multiplicity. The irradiation area of the two-dimensionally digitally modulated information beam having the first wavelength and the recording reference beam is sequentially shifted so that adjacent irradiation areas are in contact with each other along the track of the optical recording medium (1). After shifting the irradiation area over one track, the same track is sequentially shifted so that a part of the irradiation area is overlapped with the irradiation area one lap before and the adjacent irradiation area is in contact with the same track. Shift multiple recording is performed by recording the interference pattern between the information light and the recording reference light in the irradiation region as information on the hologram recording layer (3) of the optical recording medium while shifting the irradiation region with respect to Optical information recording method
In the optical recording medium, an optimum light recording condition is set as the medium manufacturing information for each multiplicity indicating the number of times the irradiation area is overlapped per track, as a medium manufacturing information, deeper than the hologram recording layer in the first recording area. It is recorded in advance on the reflective layer (7) for tracking different in thickness,
Based on the recording conditions reproduced from the tracking reflective layer in the first recording area of the optical recording medium, a test signal is applied to the hologram recording layer in a second recording area different from the first recording area. A first step of multiple recording,
A second step of obtaining data of optimum recording conditions based on a reproduction output value of the test signal recorded on the hologram recording layer of the second recording area;
And a third step of recording the data of the optimum recording condition obtained in the second step on the hologram recording layer in the first recording area.

Images