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.

The present disclosure is to provide a photopolymer composition including a polymer matrix or a precursor thereof including a reaction product of a reactive isocyanate compound having a hydrogen bonding functional group capable of forming multiple hydrogen bonds and at least one isocyanate group, and a polyol having at least two hydroxyl groups; a photoreactive monomer; and a photoinitiator, a hologram recording medium produced from the photopolymer composition, an optical element including the photopolymer composition and a holographic recording method using the photopolymer composition.

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.

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.

A method of performing a write operation in a holographic data storage system, in which schedule schedules at least one write operation across multiple non-contiguous write intervals, the write operation pertaining to a set of data to be stored in a region of a holographic recording medium. In each of the non-contiguous write intervals, the region of the holographic recording medium is exposed to an interference pattern caused by interference between a reference beam and an input beam carrying the set of data. The multiple non-contiguous write intervals have a total aggregate duration of sufficient length to cause a persistent state change in the exposed region, such that the set of data is recoverable from that region by the end of a final write interval of the multiple non-contiguous write intervals.

The purpose of the present invention is to provide a hologram reproducing apparatus and a hologram reproducing method, which are suitable for reproducing hologram. The purpose can be achieved by means of a hologram reproducing apparatus, which reproduces information signals by irradiating an optical information recording medium with reference light, and a hologram reproducing method for the hologram reproducing apparatus. The hologram reproducing apparatus is characterized in being provided with: a polarization conversion section, which converts polarization of diffracted light that is generated when the optical information recording medium is irradiated with the reference light; a light receiving section, which receives the diffracted light having the polarization thereof converted by means of the polarization conversion section; and a servo signal generating circuit section, which generates signals for moving the optical information recording medium or the polarization conversion section using the diffracted light received by means of the light receiving section.

An optical information recording/reproducing device which reproduces information from an optical information storage medium in which an interference pattern between a signal beam and a reference beam is recorded as page data includes a controller, a laser light source, a split part, an angle variable part, an optical part, a first light detector, and a second light detector, and the controller controls the angle variable part based on a control signal generated from a first signal detected by the first light detector and a second signal detected by the second light detector.

An optical information reproducing device which reproduces information from an optical information storage medium recording, as the information, a hologram which is an interference pattern between a signal beam and a reference beam, the hologram corresponding to an angle of the reference beam being a page, the device includes an image distortion learning unit which detects, based on a two-dimensional reproduction signal generated by reproducing the page, a marker which is a known pattern for detecting a position of two-dimensional data relating to the page, and learns a distortion amount which is the difference between a position of the detected marker and an ideal position, a detection unit which detects, based on the distortion amount, position information on the marker from the page, and an image distortion correction unit which corrects, based on the position information on the marker detected by the detection unit, an image distortion in the page.

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.

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.