Abstract: A hologram recording apparatus (100) includes a record angle change device (19) capable of relatively changing the record angle of a hologram recording medium (200) relative to signal light (L3) and reference light (L2); and a control device (18). The control device sets a record angle for recording a specific angle record plane as a standard record angle among a plurality of angle record planes on the hologram recording medium. Furthermore, the control device controls the record angle change device so as to change and fix the record angle after then by a predetermined angle from the set standard record angle.

Abstract: A hologram apparatus includes a light beam interfering section for allowing reference and signal light beams to interfere to form a hologram recording region; a reproducing section for allowing the reference light beam to be incident on the recording region and generating a reproduced light; an image sensor for detecting a hologram-reproduced image; a distortion determining section for detecting the distortion-detecting data from the hologram-reproduced image to determine a distortion of the hologram-reproduced image; a distortion corrector for correcting a distortion of the hologram-reproduced image; and a controller for correcting the distortion in accordance with a determined distortion.

Abstract: A spatial light modulator, in which light modulation elements are arranged in a same plane. In the spatial light modulator, a plurality of the light modulation elements are arranged such that there are at least two periods of periodic structure corresponding to an arrangement of the light modulation elements in an arbitrary direction in the plane where the light modulation elements are arranged.

Abstract: A recording apparatus includes a pulse oscillation laser (11), a half mirror (12) for splitting the pulse oscillation light of the laser into a signal light (2) and a reference light (3), an optical shutter (13) disposed in the optical path of the signal light, a beam expander (14) for converting the signal light into a light beam of a predetermined diameter, a spatial modulator (15) for modulating the recording data into two-dimensional image information, a Fourier Transform lens (16) for introducing the signal light modulated by the spatial modulator onto a recording medium (1), mirrors (17, 18) for introducing the reference light onto the recording medium with a predetermined angle, a system control unit (21), a laser driver (22), a system controller (23), a recording medium drive mechanism (24), a modulator driver (25), a data input unit (26a), and a data processing unit (27).

Abstract: A holographic recording and reproducing apparatus comprises: a pickup for moving an objective lens that focuses a coherent light beam along a recording track on a holographic recording medium and for detecting reflected light from the recording track to perform focus- and tracking-servo control; a relative velocity determination unit for determining a relative velocity of a converging position of the objective lens with respect to the holographic recording medium; a driving unit for changing a relative position of the objective lens with respect to an optical path of the coherent light beam so as to make the relative velocity fall within a predetermined range at least during a predetermined period; and a control unit for performing recording or reproduction for a recording layer during the predetermined period. The holographic recording medium includes a plurality of markers used for positioning an optical interference pattern of the coherent light beam.

Abstract: A method for holographic recording and reproducing includes a recording process and a reproducing process. In the recording process, a coherent reference beam is spatially modulated in accordance with information to be recorded to generate a signal beam, and the signal beam is converged. The converged signal beam enters and passes through a recording medium made of a photosensitive material. A diffraction grating area according to a light interference pattern is created in a portion where a 0th-order beam and a diffraction beam of the signal beam interfere with each other inside the recording medium. In the reproducing process, a reproduced wave corresponding to the signal beam is generated by illuminating the diffraction grating area with the reference beam.

Abstract: A hologram record apparatus (100) includes a parameter set device (19), a move device (20), and a control device (18). The parameter set device (19) modifies parameters for multiple recordings such as a record angle and a focal depth in relation to at least one of signal light (L3) and reference light (L2) and can fix the parameters. The move device (20) relatively moves the focus position of the signal light and the reference light in the direction along the record surface of a hologram record medium. The control device (18) performs control so that the parameter for the last recording used for recording at the m-th focus position is used as the parameter for the first recording at the m+1-th focus position.

Abstract: A hologram record apparatus (100) includes a spatial light modulator (15) and a control device (18). The spatial light modulator (15) is arranged on an optical path of signal light (L1) and divided into a plurality of cell blocks (151) arranged in a matrix. Each of the cell blocks (151) is further divided into a plurality of cells (152) arranged in a matrix. The spatial light modulator (15) can perform modulation on the cell basis. The control device (18) controls the spatial light modulator so as to modulate the signal light according to a plurality of record information sets to be recorded on a hologram record medium (200). Pluralities of modulation units (153) existing in the same cell block are not made into identical patterns. Since a plurality of cell blocks having a large pitch as compared to the pixel pitch are simultaneously or successively turned on/off, it is possible to reduce the distance between the zeroth-order light and the higher-order light.

Abstract: A hologram recording and reproducing system having compatibility has: a supporting unit for freely attachably supporting a recording medium including a photosensitive material; a signal light-generating unit for projecting a coherent light beam modulated according to a predetermined data into a recording medium and generating a diffraction grating by providing a three-dimensional light interference pattern in the recording medium; a detector unit for detecting and photoelectrically converting a diffracted light from the diffraction grating; and a demodulating unit for demodulating a predetermined data from an output from the detector unit. The detector unit has an intermediate data-generating unit for generating an intermediate data, and the demodulating unit has a conversion table in which the intermediate data and the predetermined data are uniquely associated, and demodulates the predetermined data by performing a computation based on a correlation in the conversion table.

Abstract: A hologram apparatus includes a light beam interfering section for allowing reference and signal light beams to interfere to form a hologram recording region; a reproducing section for allowing the reference light beam to be incident on the recording region and generating a reproduced light; an image sensor for detecting a hologram-reproduced image; a distortion determining section for detecting the distortion-detecting data from the hologram-reproduced image to determine a distortion of the hologram-reproduced image; a distortion corrector for correcting a distortion of the hologram-reproduced image; and a controller for correcting the distortion in accordance with a determined distortion.

Abstract: A recording medium has a recording layer capable of be performed in recording or reproducing of information with light irradiation and carried with a substrate. The recording medium includes a guide layer having guide tracks each followed by a light beam spot focused from an objective lens through the recording layer, the guide tracks disposed at a first pitch. The recording medium includes a guide track transfer region provided on the guide layer and having at least one line of a track arranged in parallel between the guide tracks adjacent to each other in the extending direction of the guide track so as to be in a direction perpendicular to the guide track within a range shorter than that of the guide track.

Abstract: A hologram recording medium is a hologram recording medium which is irradiated with light for recording information therein or reproducing information therefrom. The hologram recording medium has a recording layer made of a photo-sensitive material capable of preserving an optical interference pattern, a reflective layer disposed on one side of the recording layer opposite to the side on which an light beam impinges, and a quarter wavelength plate interposed between the recording layer and the reflective layer.

Abstract: An optical pickup device includes a photodetector divided into four light-receiving elements by two dividing lines, an incident optical system for irradiating a light beam onto an optical recording medium, and a receiving optical system for guiding a return light from the optical recording medium to the photodetector, wherein the receiving optical system includes astigmatism generating means for generating astigmatism having an astigmatism axis at an angle of 45 degree with respect to the two dividing lines.

Abstract: An optical pickup device includes a photodetector divided into four light-receiving elements by two dividing lines, an incident optical system for irradiating a light beam onto an optical recording medium, and a receiving optical system for guiding a return light from the optical recording medium to the photodetector, wherein the receiving optical system includes astigmatism generating means for generating astigmatism having an astigmatism axis at an angle of 45 degree with respect to the two dividing lines.

Abstract: An optical pickup apparatus which can be designed compact while having a plurality of semiconductor lasers. The optical pickup apparatus, which reads recorded information from an optical recording medium, comprises an optical system including light intensity detection element having a quarter-split light receiving surface, two semiconductor lasers for emitting light beams of different wavelengths, an objective lens for directing each of the light beams onto an optical recording medium to form a light spot on a recording surface, and a holographic optical element located between the quarter-split light receiving surface and the objective lens, whereby the holographic optical element eliminates coma aberration and spherical aberration of light beams launched from the two semiconductor lasers and traveled through the recording surface and the objective lens, thereby generating a predetermined amount of astigmatism.

Abstract: An optical pickup apparatus which can be designed compact while having a plurality of semiconductor lasers.

Abstract: A thin layer having a plurality of pixels is secured to a surface of a transparent substrate. A light emitting layer is formed in each of the pixels of the thin layer. A direction changing devices is provided for changing a direction of a light beam emitted from the light emitting layer and for radiating the light beam passing through the transparent substrate.

Abstract: An optical pickup device includes at least four light-receiving-surface elements, at least two semiconductor lasers, and an optical system for irradiating a light beam onto an optical recording medium through an objective lens for forming a light spot onto an information recording surface thereof. The optical system guides the return light from the light spot to the four light-receiving-surface elements through the objective. The semiconductor lasers are mounted on a plurality of flat side surfaces of a single heat sink which do not exist on a common virtual plane.

Abstract: Disclosed is an optical pickup device which comprises a beam emitting system for supplying at least two independent light beams, a common light converging optical system for converging the light beams from the beam emitting system toward a recording medium, a first optical element for reflecting one of the light beams from the beam emitting system so as to guide the reflected light beam to the light converging optical system and for transmitting returning light beams from the recording medium therethrough without causing substantial aberration, a second optical element for causing astigmatic aberration to the returned light beams which pass through the first optical element, while transmitting the returning light beams therethrough, and a light receiving system for receiving the returning light beams which have passed through the second optical element.

Abstract: An optical pickup or an optical head capable of favorably irradiating a plurality of independent different light beams and receiving return light with a simple structure. The optical pickup is composed of a beam emitting unit for supplying at least two independent light beams, a common light converging optical system for converging the light beams from the beam emitting unit to a recording medium, an integrated prism for guiding each of the light beams from the beam emitting unit incident thereto to the light converging optical system and for providing return light from the recording medium incident thereto with astigmatism, and a light receiving element for receiving the return light provided with astigmatism by the prism.