05235581 is referenced by 82 patents and cites 5 patents.

An optical disc apparatus for recording, reproducing or erasing an information signal by converging a light flux onto a recording layer through a transparent substrate. The apparatus includes one or a plurality of optical heads having a plurality of objective lenses whose aberrations have respectively been corrected for a plurality of disc substrates of different thicknesses, a cartridge for enclosing the optical disc, a discrimination hole which is formed on the cartridge, and a sensor for detecting the opening/closing state of the discrimination hole and for generating a discrimination signal. In accordance with the result of the discrimination as to the thickness of the loaded optical disc, the objective lens, in which the occurrence of the aberration is smallest, is used, so that the information signal can preferably be recorded, reproduced or erased onto/from the optical discs having different substrate thicknesses. Instead of an optical head having objective lenses, an optical head having a waveguide and a plurality of converging grating couplers whose aberrations have respectively been corrected for a plurality of disc substrates of different thicknesses is provided to achieve the same object.

Title
Optical recording/reproducing apparatus for optical disks with various disk substrate thicknesses
Application Number
7/740629
Publication Number
5235581
Application Date
August 5, 1991
Publication Date
August 10, 1993
Inventor
Yasuhiro Gotoh
Kadoma
JP
Naoyasu Miyagawa
Suita
JP
Agent
Stevens Davis Miller & Mosher
Assignee
Matsushita Electric Industrial
JP
IPC
G11B 7/00
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