摘要:
A recording technique for performing data recording onto a hologram recording medium in accordance with information on phases by performing spatial light phase modulation as spatial light modulation corresponding to recording data, and a reproducing technique for reproducing recorded data by properly reading information on phases recorded as described above are suggested. A signal beam having a phase modulation pattern provided thereto corresponding to recording data and a reference beam having a specific phase modulation pattern provided thereto are applied to the hologram recording medium. Thus, recording data can be recorded onto the hologram recording medium in accordance with information on phases. In addition, at the time of reproduction, a reference beam and a DC beam having the entire phase whose phase difference with respect to a reference phase within the reference beam is π/2 are applied to the hologram recording medium. By providing a phase difference based on π/2 as described above, the phase of a reproduction beam obtained from the hologram recording medium in accordance with application of the reference beam and the phase of the DC beam can be set to be the same. Thus, the DC beam can be added as a component of an amplitude of "1" to the reproduction beam. By reading the reproduction beam to which the DC beam is added as described above, recorded information on phases can be correctly read, and recorded data can be reproduced in accordance with the phase information.
摘要:
A method for reproducing signals in an optically recording medium of the type in which recording pits are erased or embossed by the temperature rise of the medium caused through projecting a light beam for reading out signals, or of the type in which the reflection factors of recording pits are changed by the temperature rise of the medium caused through projecting a light beam. The variation of the substantial size of the reproducing region because of the change of the temperature of the medium is prevented. For this prevention, for example, a temperature sensor (20) for sensing the temperature of a magnetooptical disc (11) is provided. By controlling the laser power and the external magnetic field according to the temperature sensed by this temperature sensor (20), the substantial size of the reproducing region is kept constant always.
摘要:
A method for reproducing signals in an optically recording medium of the type in which recording pits are erased or embossed by the temperature rise of the medium caused through projecting a light beam for reading out signals, or of the type in which the reflection factors of recording pits are changed by the temperature rise of the medium caused through projecting a light beam. The change of the substantial size of a reproducing region because of the change of the linear velocity of the medium is prevented. For this prevention, for example, a sensing means (17) for sensing the position of the reproducing region in a radial direction of the magneto-optical disc (11) during the rotation of the disc (11) at a constant speed is provided. By controlling the laser power and the external magnetic field according to the output of the sensing means (17), the substantial size of the reproducing region is so controlled as to be constant always independently of the linear velocity in each reproducing position.
摘要:
L'invention concerne un procédé et un appareil pour l'enregistrement d'informations. Selon ledit procédé, un faisceau laser de faible cohérence et de haute puissance émis par un laser à semi-conducteur (21), présentant une grande surface de rayonnement, vient éclairer la piste son (25b) d'un film cinématographique (25) après avoir subi la modulation effectuée par un modulateur de lumière (23) en fonction de l'effet électro-optique. Le modulateur de lumière (23) se trouve à une profondeur de foyer du faisceau laser qui a son point focal situé entre le modulateur de lumière (23) et une lentille de formation d'image (24). Grâce à l'emploi du faisceau laser, le temps nécessaire pour enregistrer les données vocales peut être raccourci, tandis que le bruit speckle peut être évité et la formation de l'image améliorée par le réglage du point focal du faisceau laser décrit ci-dessus. En outre, étant donné que le faisceau laser est une lumière de faible cohérence, il n'est pas nécessaire d'avoir une plaque de polarisation, ce qui permet de réduire le nombre de composants, donc de simplifier la construction d'un tel appareil et d'abaisser ses coûts de production.
摘要:
A method for reproducing signals in an optically recording medium of the type in which recording pits are erased or embossed by the temperature rise of the medium caused through projecting a light beam for reading out signals, or of the type in which the reflection factors of recording pits are changed by the temperature rise of the medium caused through projecting a light beam. The variation of the substantial size of the reproducing region because of the change of the temperature of the medium is prevented. For this prevention, for example, a temperature sensor (20) for sensing the temperature of a magnetooptical disc (11) is provided. By controlling the laser power and the external magnetic field according to the temperature sensed by this temperature sensor (20), the substantial size of the reproducing region is kept constant always.
摘要:
An optical system is provided including a light source configured to emit a light; and a polarizing splitting multiplexing device including a first prism configured to split the light into two polarized light beams having different optical path lengths, and a second prism configured to combine the two polarized light beams. The first prism includes a first reflective surface and a first polarization splitting surface facing the first reflective surface, and the second prism includes a second reflective surface and a second polarization splitting surface facing the second reflective surface.
摘要:
An optical pickup device for reading data signals recorded in an optical recording medium such as a magnetooptical disk. A light beam emitted from a source of light is split by a light-splitting element into two light beams which are linearly polarized to meet at right angles with each other and which propagate in different directions. Then, a converter element changes the phase between the oscillation components of each light beam with respect to two orthogonal axes in a plane perpendicular to the beam path. This enables two differently polarized beams to overlap on the recording medium. Thus, the effective area of irradiation is made smaller than the actual beam spot size to provide high resolution.