| 摘要 |
An optical disc apparatus of the present invention in its broader aspects is configured to have a predetermined range of A/M<SUP>2</SUP>, which is determined by an area A of a light-receiving surface of a photodetector to receive a reflected laser beam reflected on first and second recording layers of an optical disc, and a lateral magnification M (ratio of a condenser lens focal length fc to an objective lens focal length fo) of a light-receiving system to pass a reflected laser beam.
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