摘要:
A hologram recording method for forming a light interference pattern in a hologram recording medium to record information thereon. The method includes a step of interfering with a reference beam a signal beam spatially modulated by an information pattern which carries the information to generate interfered beams. The method includes a step of executing a recording sequence a plurality of times, the recording sequence including steps of irradiating the interfered beams onto a recording surface of the hologram recording medium to form a group of a plurality of holograms each corresponding to the information pattern. The method includes a step of completing the recording sequence. Different modulation conditions are set for at least one of the signal beam and the reference beam in one recording sequence and the subsequent recording sequence immediately after the one recording sequence.
摘要:
A hologram recording medium is for recording or reproducing information with light irradiated thereto. The medium has a recording layer made of a photo-sensitive material, a reflective layer disposed on the opposite side of the recording layer from a light irradiated side, tracks formed on the reflective layer such that the tracks are spaced apart by a first pitch from each other to extend without intersection, and positioning marks formed on the reflective layer such that the positioning marks are spaced apart by a second pitch from each other in a direction in which the tracks extend. The second pitch is a function of the first pitch.
摘要:
A combination of an object lens designed to appropriately converge a light beam L3 on a recording surface of a Blu-ray Disc, and an optical element which gives a phase difference distribution to a light beam L2 but does not give a phase difference distribution to the light beam L3, is provided. Another combination of an object lens designed to appropriately converge the light beam L3 on a recording surface of another optical disc, and an optical element which gives a phase difference distribution to a light beam L1 but does not give a phase difference distribution to the light beam L3, is provided. By the two combinations, information is recorded or reproduced, with respect to four types of recording media, which is a CD, a DVD, the Blu-ray Disc, and said another optical disc.
摘要:
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.
摘要:
An optical pickup apparatus includes a light source that produces and emits light beams on an optical recording medium having a plurality of recording layers; a plurality of switchable objective lenses varied in design value of a cover layer thickness; a wavefront aberration correcting unit that corrects wavefront aberration occurring when the light beams are gathered in a predetermined range from the design value of the cover layer thickness of one of the objective lenses; a detecting unit that detects a light beam reflected from the optical recording medium; and a controlling unit that controls switching of the objective lenses in accordance with the cover layer thickness of a selected one of the recording layers and that controls the wavefront aberration correcting unit.
摘要:
A liquid-crystal lens includes a hologram liquid-crystal element having a liquid crystal which provides a light beam transmitting therethrough with a phase change so as to have a wavefront of a blaze-hologram shape; and a segment liquid-crystal element including a first electrode divided correspondingly to the blaze-hologram shape, a second electrode opposed to the first electrode and a liquid crystal for providing the transmitting light beam with a phase change by voltage application to the first and second electrodes, the segment liquid-crystal element being arranged coaxial to the hologram liquid-crystal element.
摘要:
An optical pickup includes: a light source, an object lens, and an aberration correction unit for correcting aberration by giving a phase difference to a light beam. The aberration correction unit corrects astigmatism caused by an optical system of the optical pickup.
摘要:
An LCD panel will rotate based on an external control signal by a prescribed angle such portion of light flux, that enters an objective lens, corresponding to a predetermined incident point and, at the same time, will change by a prescribed length an optical path of this portion of optical flux whose aberrations are in excess of a prescribed standard value. It is thus possible to compensate the wave-front aberrations due to the differences in the effective optical-path length and also to control the effective numerical aperture of the objective lens by utilizing linearly polarized light as the light to be emitted from the laser beam source. It is also possible to compensate the aberrations due the differences in the substrate thickness of the optical recording medium and those due to a tilt of the optical recording medium.