Sony Corporation

Shuichi Igarashi

Yasuaki Nakane

Hiroshi Nakayama

Sakuya Tamada

Junichi Iwai

Atsushi Takeuchi

Senri Miyaoka

Mikio Yoshida

Susumu Sakamoto

Teruo Chiba

An optical disc having, as a recording layer, a first Sb--Se based thin film, a Bi--Te based thin film and a second Sb--Se based thin film, deposited in this order on a disc substrate, and a thin Al film deposited on the recording layer, is disclosed. Each of the first Sb--Se thin film and the second Sb--Se thin film has a composition such that Se accounts for not less than 70 atm % of the composition. The film thicknesses of the first Sb--Se based thin film and the second Sb--Se based thin film are set to not larger than 30 nm and to 15 to 25 nm, respectively, with the reflectance of the recording layer with respect to the laser beam with a wavelength of 680 nm being 10 to 25%. Alternatively, the first Sb--Se based thin film is of Sb.sub.2 Se.sub.3, the Bi--Te based thin film is of Bi.sub.2 Te.sub.3 and the second Sb--Se based thin film is of Sb.sub.2 Se.sub.3, and the film thickness of the second Sb--Se based thin film is set to 15 to 25 nm, so that the reflectance of the recording layer with respect to the laser beam with a wavelength of 680 nm will be 10 to 25%.

Optical disc

A magneto-optical disk having a four-layer structure formed of a first protective dielectric layer, a recording magnetic layer, a second protective dielectric layer and a reflective metal layer is disclosed. The constraints for the film thicknesses of the various layers are determined not only from the optical and magneto-optical aspects, but from the aspect of the dynamic thermal response. The recording magnetic layer is a magnetic layer mainly formed of TbFeCo and having a film thickness of not less than 180 .ANG. and not more than 280 .ANG.. The first protective dielectric layer is a nitride film having a film thickness such that the product of its refractive index and the film thickness is not less than 0.2 and not more than 0.35 times the wavelength of the laser light employed. The second protective dielectric layer is a nitride film having a film thickness such that the product of its refractive index and the film thickness is not less than 0.1 and not more than 0.15 times the wavelength of the laser light employed. The the reflective metal layer is a metal layer having a film thickness of not less than 500 .ANG. and not more than 1000 .ANG., with the metal being electro-chemically less noble than the material of the recording magnetic layer and having a reflectivity at the boundary with the second protective dielectric material of not less than 70%.

Magneto-optical disk

A magnetic optical disc comprising a magnetic optical recording layer on a transparent substrate. The disc measures less than 80 millimeters in outer diameter and is capable of recording at least 130 megabytes of compressed digital signals. The extreme storage density of the disk is achieved by the suppression of double refraction characteristics near the center area of the disk, whereby the minimum diameter of the recording area can be made smaller. This allows a small-diameter magnetic optical disc to provide a recording area of sufficient storage capacity. In combination with a novel magnetic optical recording system, the disc may illustrative accommodate at least 60 minutes of the user's audio signals while measuring smaller than any other conventional discs of comparable storage capacity.

High density small-diameter magnetic optical disk

An image display apparatus having light beam sources for generating light beams, an optical modulator for modulating the light beams by image signals to be projected, a deflection device for deflecting the modulated light beams, the deflection device including a polygon mirror and an auxiliary reflection mirror provided near the polygon mirror such that the modulated light beams are reflected from the polygon mirror to said auxiliary reflection means and back toward the polygon mirror, a device for supplying the modulated light beams to the polygon mirror with predetermined angles relative to a rotational plane of the polygon mirror, such that the modulated light beams incident upon the polygon miror are reflected a plurality of times by the polygon mirror, and a projection device for projecting the modulated and deflected light beams from the deflection device on a screen or the like.

Image display apparatus with increased raster scan rate of laser beams

A laser beam deflection apparatus is comprised of a polygon mirror having a plurality of reflection surfaces, a laser beam incident on the reflection surfaces of the polygon mirror, and n number of reflection devices positioned in facing relation to the polygon mirror, and aligned in a rotational direction of the polygon mirror for reflecting the laser beam reflected from one of the reflection surfaces back towards the one of the reflection surfaces of the polygon mirror, whereby the laser beam is twice reflected by the one of the reflection surfaces and is deflected through a predetermined angle n times during each predetermined increment of rotation of the plurality of reflection surfaces of the polygon mirror.

Growing community of inventors

Miyagi, Japan

Shuichi Igarashi