Plattenunterscheidungsverfahren und -vorrichtung

摘要

An optical disk apparatus comprises objective lenses (34,35) for converging on first or second type optical disks an optical beam corresponding to different numerical apertures. For discriminating a disk (10) the objective lens (34) having the greater numerical aperture is moved along its optical axis to search the disk, and the type of the disk is discriminated from the waveform of the signal detected during search.