Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Tatsuo Ito

Hiroaki Yamamoto

Teruhiro Shiono

Seiji Nishino

Yoshiaki Komma

Michihito Ueda

Kazuo Yokoyama

Hideki Hayashi

Masaki Suzuki

Toshiyuki Watanabe

Shinichi Mizuguchi

Shin-ichi Kadowaki

Sadao Mizuno

Tomotada Kamei

Eishin Mori

Shin-Ichi Kadowaki

An optical recording medium which is a multilayer optical recording medium including a plurality of recording layers and records or reproduces information by the irradiation of light having a wavelength of &#x3bb;0. At least one recording layer out of a plurality of recording layers includes a variable absorption film. The variable absorption film contains a material in which an electron energy has a band structure, and the absorption end of an absorption spectrum moves toward a longer wavelength side with a rise in temperature when light is absorbed by transition between electron bands, has a first absorptance to light having a wavelength of &#x3bb;0 when a film temperature is a first temperature (application environment temperature), and has a second absorptance higher than the first absorptance to light having a wavelength of &#x3bb;0 when a film temperature is a second temperature higher than the first temperature.

Optical recording medium, optical information processor, and optical recording/reproducing method

An object of the present invention is to acquire optimum recording characteristics of an optical recoding medium having multiple data layers, with respect to each of the multiple data layers without increasing learning time required for learning a relation between aberration amount and optimum recording compensation with respect to each of the multiple data layers. The present invention includes a wavefront converter which is driven in such a manner as to reduce the aberration amount detected by an aberration detector. An output controller holds learned data as to the relation between the driving amount of the wavefront converter and the output of a light source, and controls the output of the light source based on the driving amount of the wavefront converter and the learned data.

Optical head device, optical recording device, and optical recording method

Disclosed is an optical head, which comprises a semiconductor laser, a collimator lens for converting a beam emitted from the semiconductor laser light into parallel beam, a lens frame holding the collimator lens, a beam shaping prism for shaping the parallel beam passing through the collimator lens from an elliptic section into a circular section, an objective lens for converging the parallel beam passing through the beam shaping device on an optical recording medium formed with a track, and a photodetector for detecting a reflected light or transmitted light from an optical disk. The collimator lens is adhesively fixed to the lens frame at two positions opposed to one another along a radial direction corresponding to the minor axis direction of the cross section of the incoming parallel beam into the beam shaping prism. The optical head can suppress the displacement of detected-light spots in an photodetector caused by the displacement of an optical axis due to change in ambient temperature.

Optical head and optical recording medium drive

An optical head device includes: an optical element collecting light reflected from a reproduction information layer (a target information layer in an optical information recording medium) and light reflected from information layers adjacent to the reproduction information layer at different positions; a light receiving element obtaining a detection signal from the reflected light collected by this optical element; and arithmetic circuitry obtaining a reproduction signal from this detection signal. The light receiving element includes: a first light receiving portion detecting a first detection signal from light containing the light reflected from the reproduction information layer; a second light receiving portion detecting a second detection signal from light reflected from a first adjacent information layer located more distant from the condensing lens than the reproduction information layer; and a third light receiving portion detecting a third detection signal from light reflected from a second adjacent information layer located closer to the condensing lens than the reproduction information layer. The arithmetic circuitry uses constants K and L determined depending on spaces between the reproduction information layer and the adjacent information layers, so as to subtract the K-times second detection signal and the L-times third detection signal from the first detection signal.

Optical head device and optical information reproducing device

To provide a laser driving apparatus which is inexpensive and has high reliability in spite of using a plurality of light sources, since a multi-wavelength light source is required for treating different kinds of optical disks such as CD, DVD or the like. In a two-wavelength LD apparatus including: a semiconductor laser ; a semiconductor laser ; and a photo detector , optical outputs of the semiconductor lasers are controlled by APC circuits on the basis of respective voltage values of variable resistors connected in series to the photo detector . Alternatively, in the two-wavelength LD apparatus including: the semiconductor laser ; the semiconductor laser ; and the photo detector , the optical outputs of the semiconductor are controlled by the APC circuits on the basis of respective intermediate potentials of variable resistors connected in parallel with the photo detector

Laser drive device, optical head, and optical information processor

In a photodetector, the minimum size of the photodetection area for detecting a focus error signal from a light beam on the inner radius side of a hologram is made smaller than the minimum diameter of diffracted light beam spots ( ) for recording and reproduction, and when a CD is reproduced, a light beam close to the optical axis is made to significantly contribute to the focus error signal and the minimum size of the photodetection area for detecting the focus error signal from a light beam from the peripheral side of the hologram is made larger than the minimum diameter of diffracted light beam spots ( ) for recording and reproduction, whereby the focus error signal is made equal to the normal focus error signal when a DVD is reproduced, so that the focus offset variation caused when the base material thickness varies can be reduced.

Optical head device

In a photodetector, the minimum size of the photodetection area for detecting a focus error signal from a light beam on the inner radius side of a hologram is made smaller than the minimum diameter of diffracted light beam spots (,) for recording and reproduction, and when a CD is reproduced, a light beam close to the optical axis is made to significantly contribute to the focus error signal and the minimum size of the photodetection area for detecting the focus error signal from a light beam from the peripheral side of the hologram is made larger than the minimum diameter of diffracted light beam spots (,) for recording and reproduction, whereby the focus error signal is made equal to the normal focus error signal when a DVD is reproduced, so that the focus offset variation caused when the base material thickness varies can be reduced.

Optical head apparatus

Output efficiency control device, projection-type display apparatus,

The diffractive optical modulator of the invention includes: a plate having a portion functioning as a first electrode; a spacer layer formed on the plate; and a grating consisting of a plurality of beams having a portion functioning as a second electrode, both ends of the beams being supported on the spacer layer. In the diffractive optical modulator, by adjusting a voltage applied between the first electrode and the second electrode, a distance between the beams and the plate is varied, thereby controlling the diffraction efficiency. An insulating layer is further provided between the plate and the plurality of beams.

Diffractive optical modulator and method for producing the same,

A circular arc illumination apparatus includes a light source section for emitting rays, a condensing optical system for condensing the rays emitted by the light source section, a rotating mirror driven by a motor and reflecting the condensed rays from the condensing optical system, and a circular arc-shaped bending mirror for reflecting the rays reflected by the rotating mirror toward a mask so that the rays become incident on the mask. The apparatus effectively utilizes light emitted by the light source section, exposes an object uniformly, and is practical and economical for exposing a large substrate.

Circular arc illumination apparatus

A circular arc illumination apparatus includes a light source device, a condensing optical system for condensing rays emitted by the light source device, and a scanning optical system for transmitting the rays to an object to be scanned. The scanning optical system includes a driving device, a rotating mirror driven by the driving device, an angular velocity detecting device for detecting an angular velocity of the rotating mirror, a controller for controlling the driving device based on an angular velocity of the rotating mirror detected by the angular velocity detecting device so as to vary the angular velocity in one time scanning, and a circular arc-shaped bending mirror for reflecting scanning rays reflected by the rotating mirror to the object. The axis of the bending mirror is coincident with a rotary axis of the rotating mirror.

Growing community of inventors

Osaka, Japan

Tatsuo Ito