A hologram recording and playback device is provided with: a medium rotation unit which rotates a hologram recording medium around a predetermined rotational axis; a movement unit which is capable of moving the position of the medium rotation unit within a plane that is perpendicular to the rotational axis; an orthogonal incident angle modification unit which is capable of modifying an orthogonal incident angle; a medium rotation control unit which controls the medium rotation unit so as to rotate the hologram recording medium; an eccentricity compensation unit which performs positioning control of the movement unit; an orthogonal incident angle control unit which controls the orthogonal incident angle modification unit; and an orthogonal incident angle calculation unit which calculates the orthogonal incident angle.

A holographic light-emitting module includes a light source module and a light shape control module. The light source module is configured to provide a signal light beam and a reference light beam, in which polarizations of the signal light beam and the reference light beam are orthogonal. The light shape control module is configured to receive the signal light beam and the reference light beam propagated from the light source module, in which the signal light beam and the reference light beam are modulated and emitted by the light shape control module The reference light beam is surrounded by the signal light beam and located at a center of the signal light beam, and the signal light beam and the reference light beam are partially overlapped.

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.

An optical-information recording/reproducing apparatus of the present invention is capable of carrying out position detection of a reproduction image even if reproduction image data with incomplete alignment marks (markers) is obtained. A relative correlation value is calculated from a first correlation value retained by a first correlation-value retaining unit and a second correlation value retained by a second correlation-value retaining unit, and pass/fail of a position detection result of the marker is judged according to the relative correlation value. The pass/fail of the position detection result is judged by mutually comparing the detection positions of the markers judged as passes by the relative correlation-value judgement, the positions of the markers judged as fail by the relative correlation-value judgement or the mutual position judgement is complemented, and the position of two-dimensional data is detected based on the pass-judged markers and the complemented markers.

To provide an optical information recording and reproducing apparatus capable of correct positioning, in an optical information recording and reproducing apparatus which branches a light beam into reference light and signal light to cause interference and records an obtained interference fringe as a hologram on an optical information recording medium and reproduces the hologram recorded by applying the reference light onto the optical information recording medium, the apparatus has an image pickup element which detects reproduction light passing through an aperture 101 in reproduction light obtained by applying the reference light onto the optical information recording medium and generates a reproduction signal, photo detectors 104a, 104b, 104c, and 104d that are different from the image pickup element and detect reproduction light applied on a location on the periphery of the aperture 101, and a computing unit which computes a position error signal based on outputs from the photo detectors.

A method of fabricating an optical element includes providing a substrate of a transparent material in which is to be formed a plurality of birefringent nanostructures spaced apart; generating from the output of a source of femtosecond laser pulses a laser beam group comprising a plurality of focused seeding beams having a circular polarisation; directing the laser beam group onto the surface of the substrate at a first position and applying one or more femtosecond laser pulses from each beam to corresponding volumes in the substrate; repeatedly translating the laser beam group relative to the substrate parallel to the line of seeding beams; translating the laser beam group relative to the substrate and repeating the repeated translation and application of the femtosecond laser pulses; wherein the relative translation of the laser beam group and the substrate aligns the writing beam with successive corresponding volumes.

A method of writing voxels to a substrate using a laser writing system comprises forming a first voxel at a first position in a substrate using a first laser pulse; detecting light emitted or scattered by the substrate as a result of forming the first voxel; determining whether the detected light satisfies a predetermined constraint; and, when the detected light does not satisfy the predetermined constraint, adjusting an amplitude of a second laser pulse. Light emission or scattering from the substrate as a result of forming a voxel is related to the properties of the formed voxel. By monitoring such emission or scattering, it is made possible to compensate for variations in performance of the laser writing system. Also provided herein are a laser writing system and computer program product which implement the method.

When a simple magnification optical system is used in reproduction of a recording medium in which a large number of minute modified regions are three-dimensionally formed inside solid matter, contrast is insufficient and interlayer crosstalk is increased, and therefore, it is impossible to take a sufficient S/N ratio. Provided is a recording medium in which at least one layer is configured by a set of two adjacent sub-layers, and dots on a sub-layer correspond to a recording data 1 and dots on the other sub-layer correspond to 0. These data are played back.