Patent ID: 8077573

Claim:
An optical disk apparatus for recording and/or reproducing information in and/or from a plurality of types of optical disks, comprising: an acquisition unit configured to acquire a predetermined type of signal from reflected light obtained by radiating a predetermined type of laser on an optical disk; a comparator configured to perform a comparison of the waveform of the signal acquired by the acquisition unit with a comparative waveform of the signal, each comparative waveform obtained by radiating a predetermined type of laser on a predetermined type of optical disk, and each comparative waveform being stored in a memory before use in a comparison; and an identification unit configured to identify the type of the optical disk based on the result of at least one comparison performed by the comparator, the identification unit using at least one coincidence degree value; wherein each coincidence degree value is based on a difference between a time function of the waveform of the signal acquired by the acquisition unit, and a time function of a comparative waveform used in the at least one comparison.