''PD'' (powerful optical disk system) for Multimedia

The use of CD-ROM has become widespread. PC users have generally been satisfied with the performance CD-ROM's, however, there is also a demand for larger-capacity removable rewritable media for ''Multimedia'' applications. The ''PD'' system offers users an optical disk which is easily handled such as floppy disks presently in use. In addition, ''PD'' can also read CD-ROM at fourtimes of the speed using a single common slot for both CD-ROM and PD media. The PD system (name of the new optical disk system prososed by Matsushita Electric Industrial. Co., Ltd.) has good compatibility for pit and groove recording. We calculated the reflectivity, tracking error, and ROM modulation, and varied the groove depth and width to maximize performance. A signal was written on various pregroove depths, and the reproduced signal ratio was measured. We obtained good results by using a phase-change material with the PD optical disk.