Abstract: An optical system for holographic storage includes a reference light path, a signal light path, a servo light path and a reproduction light path. The reference light path and the signal light path contain a first Fourier lens and a second Fourier lens for transmitting reference light and signal light carrying data information, and adjusting the incident position and angle of the reference light and the signal light on a storage medium. The optical system includes a reference light objective lens for converging the reference light, a third Fourier lens for performing Fourier transformation on a signal light field, and a fourth Fourier lens for performing Fourier transformation on a reproduced signal light field to read the data information. The first Fourier lens, the second Fourier lens, the third Fourier lens, the fourth Fourier lens and the reference light objective lens is respectively a Fresnel lens or a meta lens.

Abstract: An optical track format of a holographic storage optical disc includes a lead-in area, a data area and a lead-out area. The data area is provided with data holographic positioning marks for marking reading/writing position of data holograms on the optical track and start positioning marks for marking position on the optical track where data holograms start to be recorded. The start positioning marks may also contain address encoding information. Such optical track can be encoded by performing binary encoding by length of the optical track between two consecutive notches, or performing binary encoding by high and low levels of a level signal.

Abstract: A transmission-type holographic optical storage medium includes a first substrate, a second substrate, a recording layer and a dichroic layer. The recording layer is used for recording a hologram with data information. One side of the second substrate facing the recording layer is engraved with a concave-convex structure for a servo light beam to position a recording/reading position and achieve a servo track locking function. The dichroic layer can reflect the servo light beam and transmit recording/reading light. The storage medium according to the present invention is less susceptible to influence of external environment and is more stable compared with a conventional reflection-type storage medium.

Abstract: A holographic storage optical system includes a storage medium, a recording unit, an imaging unit and a servo unit. The recording unit comprises a movable Fourier lens, by which the positions and irradiation angles of a signal light spot and a reference light spot are adjusted. The servo unit comprises a calibration lens for adjusting the positions of a servo light spot in the horizontal and vertical directions so that the servo light spot is located at an optimal position relative to signal light beam and reference light beam. The beam calibrating method comprises (1) before recording a data hologram, burning a calibration hologram at a calibration holographic positioning mark on an optical track of a storage medium; (2) before reproducing the data hologram, using the calibration hologram to optimize the signal-to-noise ratio of the hologram reproduced by adjusting the calibration lens and the Fourier lens.

Abstract: A multi-channel multiplexing method for a disc storage medium includes: S1) recording holograms at holographic positioning marks of the storage medium by a reference light beam and a signal light beam, S2) rotating the storage medium in a circumferential direction and repeatedly performing step S1 until the holograms have been recorded at all the holographic positioning marks on optical tracks, S3) translating the storage medium to switch an optical head to another optical track, S4) repeating steps S1-S3 until recording of one cross channel is completed, S5) changing a relative angle of the center of the storage medium with respect to the optical head, and repeating steps S1-S4 to complete recording of another cross channel, S6) repeating steps S1-S5 until recording of all cross channels is completed, and S7) reproducing the holograms at any channel or recording position of the storage medium by using the same beam of reference light.

Abstract: The invention discloses a holographic multiplex recording method, which combines technical advantages of angle multiplexing and shift multiplexing, and improves capacity and stability of a system. A medium contracts and expands due to environmental temperature fluctuations, which causes broken Bragg condition. However, the angle multiplexing has the advantages that the broken Bragg condition caused by contraction and expansion of the medium can be corrected by controlling an incident angle of a reference beam and an emitting wavelength of a laser, and the problem of a weak reproduction signal caused by the environmental temperature fluctuations is solved. On the other hand, the advantages of shift multiplex recording are that cross-write noise is not accumulated and that a multiplexing number can be improved by using a cross-shift multiplex method. According to the present invention, a large-capacity recording device with high stability is realized by combining the two technologies.

Abstract: According to a positioning method for a hologram in a disk-type holographic storage medium, a guide groove is formed in advance in the disk-type storage medium and is scribed with a positioning marker that includes index information, position information and crossing angle information. The positions of a positioning laser beam and a recording/reproducing laser beam are applied to the same medium position. When an optical head accesses a recording/reading position at a high speed, the shift multiplex recording/reading is performed starting from a marker position. A servo system controls the laser beams to move along the guide groove and ensures that a focused beam is focused on the medium. According to the method, the position and angular information can be quickly positioned in process of performing cross-shift multiplex recording/reading, the recording/reading speed of the system is improved, and random access is achieved.

Abstract: The invention relates to a positioning method and device for a hologram in a card-type holographic storage medium, which can be used for beam positioning of cross-shift multiplexing and belong to the technical field of optical holographic storage. A guide groove in a grid shape is engraved on a card-type storage medium, and is provided with positioning markers. Each marker includes position information and direction information, can control an optical head to move along the guide groove, and shift multiplexing/reproducing is performed when recognizing the positioning markers. Since the card-type medium is adopted, a 90-degree rotation can be executed three times, and a total of four times of shift multiplex recording is performed. Random access can be achieved even in a medium that is rotated and used by adopting the positioning method and device described in the present invention.

Abstract: The present invention discloses a reflective holographic storage method and device, in which a reflection layer is plated on a back side of a holographic storage medium, and a new reference light is formed by utilizing the reflection layer, so that a phase conjugate reproduction light of a hologram is obtained. According to the invention, a recording device and a reading device can be provided on the same side of a medium, thereby obtaining a more compact system, reducing design difficulty, improving system stability, and improving the SNR (signal-noise ratio) of reproduction light by the interference between reproduction light and a conjugate reproduction light.

Abstract: A holographic multiplexed recording method for increasing storage capacity is disclosed. In a holographic recording and reproducing device, the moving direction of a storage medium is not coplanar with the plane where the optical axes of signal light and reference light are located, or the relative moving direction of the storage medium and the signal light or the reference light is not coplanar with the plane where the optical axes of the signal light and the reference light are located. Through the method, a certain angle exists between the grating vector direction and the moving direction or the relative moving direction, so that the phenomenon that the grating vector directions are the same does not occur when the medium is subjected to multiplexed recording after being rotated or flipped. Not only is multiplexing number increased, but also crosstalk caused by the same grating vector direction is prevented.

Abstract: The present invention relates to a holographic data storage device with a single-arm structure, and belongs to the technical field of optical holographic storage. According to the device disclosed in the present invention, a part of a reference arm and a part of a signal arm are integrated together to form a single-arm structure, which can not only reduce the number of optical and mechanical elements, but also reduce the system volume and cost without degrading performance. In addition, a signal beam and a reference beam share the same relay lens, so that the impact of environmental interference on the two beams is equal, and the stability of the entire system is improved.

Abstract: The present invention relates to a holographic storage device and method for simultaneously recording and reading on two sides, and pertains to the technical field of optical holographic storage. The device and method disclosed in the present invention use a characteristic that orthogonal light would not interfere with each other and a Bragg selectivity characteristic for holographic storage, and use two optical heads to constitute two interference fields orthogonal in polarization directions on two sides of a same position of a holographic storage medium, so as to perform two-path simultaneous recording and reading on a hologram. The device and method provided in the present invention implement two-path parallel recording and reading of holographic storage, and combine shift multiplexing and circumferential rotation multiplexing, thereby improving the speed of an information data recording and reading process while increasing a capacity of the holographic storage.

Abstract: The present patent relates to a parallel reproducing holographic disk reading method and device, and belongs to the technical field of optical holographic storage. According to an angle-shift multiplexing method included in the present patent, multiplex recording is performed by simultaneously changing an incident angle of a reference light and moving a medium with a fixed angle change amount and a fixed shift amount. In this method, the reference light can be split for incidence, and then holograms in different units can be simultaneously reproduced. According to the method disclosed by the patent, a recorded hologram can be read and written in real time, and a recorded signal can be checked under a condition of satisfying a response time required by the medium.

Abstract: The present invention relates to the technical field of holographic multiplexing storage, and in particular, to a multiplexing method for increasing storage capacity in a disc-type holographic storage medium. According to the method disclosed by the present invention, holograms with different grating vector directions can be overwritten and recorded in the same storage medium according to Bragg selection characteristics of volume holographic records, and the obtained holograms do not affect each other. According to the method disclosed by the present invention, on the premise of ensuring low crosstalk between data pages, the multiplexing number of shift multiplexing storage is increased by using a cross-shift multiplexing method, and the storage density is improved.

Abstract: The present patent relates to a parallel reproducing holographic disk reading method and device, and belongs to the technical field of optical holographic storage. According to an angle-shift multiplexing method included in the present patent, multiplex recording is performed by simultaneously changing an incident angle of a reference light and moving a medium with a fixed angle change amount and a fixed shift amount. In this method, the reference light can be split for incidence, and then holograms in different units can be simultaneously reproduced. According to the method disclosed by the patent, a recorded hologram can be read and written in real time, and a recorded signal can be checked under a condition of satisfying a response time required by the medium.

Abstract: The present invention relates to a method for accurately detecting and controlling a position of an optical head. According to the present invention, by utilizing the narrow shift selectivity of a spherical reference beam shift multiplexing technology, a control area that includes an x-direction position control unit and a y-direction position control unit and that is separated from a data area is formed in a storage medium. Like the data area, holograms of special patterns are recorded in the control area, when the data is read, information in the control area is read first, and the position of the optical head relative to the hologram in the data area can be detected in the x direction and the y direction respectively according to the information read by the hologram in the control area, so that reference light is controlled to the correct position shown by the address.

Abstract: The present invention relates to a holographic storage device and method for simultaneously recording and reading on two sides, and pertains to the technical field of optical holographic storage. The device and method disclosed in the present invention use a characteristic that orthogonal light would not interfere with each other and a Bragg selectivity characteristic for holographic storage, and use two optical heads to constitute two interference fields orthogonal in polarization directions on two sides of a same position of a holographic storage medium, so as to perform two-path simultaneous recording and reading on a hologram. The device and method provided in the present invention implement two-path parallel recording and reading of holographic storage, and combine shift multiplexing and circumferential rotation multiplexing, thereby improving the speed of an information data recording and reading process while increasing a capacity of the holographic storage.

Abstract: The invention relates to a positioning method and device for a hologram in a card-type holographic storage medium, which can be used for beam positioning of cross-shift multiplexing and belong to the technical field of optical holographic storage. A guide groove in a grid shape is engraved on a card-type storage medium, and is provided with positioning markers. Each marker includes position information and direction information, can control an optical head to move along the guide groove, and shift multiplexing/reproducing is performed when recognizing the positioning markers. Since the card-type medium is adopted, a 90-degree rotation can be executed three times, and a total of four times of shift multiplex recording is performed. Random access can be achieved even in a medium that is rotated and used by adopting the positioning method and device described in the present invention.

Abstract: The invention discloses a holographic multiplex recording method, which combines technical advantages of angle multiplexing and shift multiplexing, and improves capacity and stability of a system. A medium contracts and expands due to environmental temperature fluctuations, which causes broken Bragg condition. However, the angle multiplexing has the advantages that the broken Bragg condition caused by contraction and expansion of the medium can be corrected by controlling an incident angle of a reference beam and an emitting wavelength of a laser, and the problem of a weak reproduction signal caused by the environmental temperature fluctuations is solved. On the other hand, the advantages of shift multiplex recording are that cross-write noise is not accumulated and that a multiplexing number can be improved by using a cross-shift multiplex method. According to the present invention, a large-capacity recording device with high stability is realized by combining the two technologies.

Abstract: The present invention discloses a reflective holographic storage method and device, in which a reflection layer is plated on a back side of a holographic storage medium, and a new reference light is formed by utilizing the reflection layer, so that a phase conjugate reproduction light of a hologram is obtained. According to the invention, a recording device and a reading device can be provided on the same side of a medium, thereby obtaining a more compact system, reducing design difficulty, improving system stability, and improving the SNR (signal-noise ratio) of reproduction light by the interference between reproduction light and a conjugate reproduction light.