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.

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.

Provided is a method of manufacturing an optical disk having at least a cover layer, a first information recording surface, a first intermediate layer, a second information recording surface, a second intermediate layer, and a third information recording surface in order from a surface irradiated with a light beam on at least one side, wherein a numerical aperture of an objective lens that converges the light beam on any of the recording surface of the optical disk when information recording or information reproduction of the optical disk is performed is 0.91, standard value dk of each thickness from the surface to the first to third information recording surfaces is set on the premise of standard refractive index no, where k is 1, 2, 3, and a target value of each actual thickness from the surface to the first to third information recording surfaces is determined by a product of conversion coefficient g(n) depending on refractive index n from the first to third information recording surfaces, and standard value dk.

Provided is a method of manufacturing an optical disk having at least a cover layer, a first information recording surface, a first intermediate layer, a second information recording surface, a second intermediate layer, and a third information recording surface in order from a surface irradiated with a light beam on at least one side, wherein a numerical aperture of an objective lens that converges the light beam on any of the recording surface of the optical disk when information recording or information reproduction of the optical disk is performed is 0.91, standard value dk of each thickness from the surface to the first to third information recording surfaces is set on the premise of standard refractive index no, where k is 1, 2, 3, and a target value of each actual thickness from the surface to the first to third information recording surfaces is determined by a product of conversion coefficient g(n) depending on refractive index n from the first to third information recording surfaces, and standard value dk.

An optical information processing device writes and reads information on an information recording medium having recording layers. The optical information processing device includes: first and second light sources; a light condensing element that condenses light from the first and second light sources on the medium; a first photodetector that receives light reflected by the medium after being emitted from the first light source and generates a first focusing error signal; a second photodetector that receives light reflected by the medium after being emitted from the second light source and generates a second focusing error signal; and a focusing control circuit that controls the light condensing element by using the first focusing error signal in such a manner that the light from the second light source is condensed on each of the recording layers. The second focusing error signal is used to add a correction to the focusing control circuit.

An optical information processing device writes and reads information on an information recording medium having recording layers. The optical information processing device includes: first and second light sources; a light condensing element that condenses light from the first and second light sources on the medium; a first photodetector that receives light reflected by the medium after being emitted from the first light source and generates a first focusing error signal; a second photodetector that receives light reflected by the medium after being emitted from the second light source and generates a second focusing error signal; and a focusing control circuit that controls the light condensing element by using the first focusing error signal in such a manner that the light from the second light source is condensed on each of the recording layers. The second focusing error signal is used to add a correction to the focusing control circuit.

An optical information processing device writes and reads information on an information recording medium having recording layers. The optical information processing device includes: first and second light sources; a light condensing element that condenses light from the first and second light sources on the medium; a first photodetector that receives light reflected by the medium after being emitted from the first light source and generates a first focusing error signal; a second photodetector that receives light reflected by the medium after being emitted from the second light source and generates a second focusing error signal; and a focusing control circuit that controls the light condensing element by using the first focusing error signal in such a manner that the light from the second light source is condensed on each of the recording layers. The second focusing error signal is used to add a correction to the focusing control circuit.

An optical information processing device writes and reads information on an information recording medium having recording layers. The optical information processing device includes: first and second light sources; a light condensing element that condenses light from the first and second light sources on the medium; a first photodetector that receives light reflected by the medium after being emitted from the first light source and generates a first focusing error signal; a second photodetector that receives light reflected by the medium after being emitted from the second light source and generates a second focusing error signal; and a focusing control circuit that controls the light condensing element by using the first focusing error signal in such a manner that the light from the second light source is condensed on each of the recording layers. The second focusing error signal is used to add a correction to the focusing control circuit.

Provided is a holographic data storage system characterized by including: a first polarizing beam splitter (PBS), wherein at least either of a first lens module and a second lens module transmits P-polarized light and reflects S-polarized light; a relay lens collecting light passing through the first PBS; a mirror reflecting the light collected through the relay lens back to the relay lens; and a quarter wave plate located between a second PBS beam splitter and the relay lens, converting transmitted linearly polarized light into circularly polarized light, and converting the circularly polarized light into linearly polarized light. By reducing the volume of the relay lens, it is possible to decrease the size of the holographic data storage system, and by decreasing the number of lenses, it is possible to lower manufacturing costs.