Mitsubishi Denki Kabushiki Kaisha

Keizo Kono

Shinsuke Shikama

Teruo Fujita

Mitsushige Kondo

Natsuro Tsubouchi

Shiro Hine

Toshiaki Suhara

Mitsushige Kondou

Hiroshi Nishihara

An optical IC-type head assembly for recording and for reading information on an optical disc, comprising a substrate, a light guiding layer comprising a dielectric thin film formed monolithically on the substrate, a laser oscillator for injecting the laser beam into the light guiding layer, a grating coupler for converging the laser beam on the optical disc, and a photo detector for receiving the beam reflected by the optical disc and coming out of the grating coupler. In one embodiment the substrate is made of material having cleavability. One side surface of the light guiding layer receiving the laser beam is a break surface formed by cleaving the substrate along the cleavage plane. The photo detector is disposed at the break surface of the light guiding layer. The substrate is preferably made of single crystal material. In another embodiment, a beam splitter is disposed between the laser oscillator and the grating coupler for splitting the reflected beam coming out of the grating coupler into two symmetrical beams. Each split beam forms an acute angle with respect to the optical axis of the reflected beam. The acute angle is preferably less than 30 degrees. The beam splitter may converge each of the split beams at a photo detecting element disposed between the laser oscillator and the grating coupler.

Method of producing optical head assembly

Optical head assembly with efficient light source coupling surface and

An optical head assembly for recording information on an optical disc or for taking out information already recorded, the optical head assembly including a semiconductor substrate and a dielectric light conducting layer formed on the substrate, the light conducting layer being internally formed with optical elements for converging laser beam from a laser beam source onto the optical disc and directing the reflected beam from the optical disc surface toward a photo detector. Output signal from the photo detector is used for reading information and also for allowing the optical head assembly to trace a track on the optical disc.

Head assembly for optical disc

A focusing error detecting device used in a head assembly for recording information to a recording surface of an optical disc or reading out information already recorded, the focusing error detecting device including a diffraction grating for focusing light which has been introduced from a light source into a thin-film waveguide layer, onto the recording surface, and two light receiving diffraction gratings for conducting the light reflected by the recording surface again into the waveguide layer. The two light receiving diffraction gratings have optical characteristics which differ from each other, depending the position of a focused spot of the light focused on the recording surface by the focusing diffraction grating. Therefore, by comparing the intensity of light from one light receiving diffraction grating with that from the other light receiving diffraction grating, there can be seen a positional relationship between the focused spot and the recording surface.

Focusing error detecting device in head assembly for optical disc

Growing community of inventors

Kyoto, Japan

Keizo Kono