OPTICAL DISK AND ITS READER AND PRODUCTION OF OPTICAL DISK

摘要

PURPOSE: To obtain an optical disk of a write enable type with which an improvement in recording capacity as compared with conventional disks is possible, a reader for reading out recording signals from this disk and a process for producing the optical disk. CONSTITUTION: Prepit information 4 including at least the address information of the optical disk write enable type having information recording tracks 2 and the guiding tracks 3 for guiding a light beam to these information recording tracks 2 is recorded in the guiding tracks 3 of the optical disk. The reader has a photodetecting means for receiving the reflected light of the light beam cast to the information recording tracks 2 of the optical disk by photodetectors bisected by a first bisecting line parallel with the radial direction of the optical disk and a prepit information extracting means for extracting the prepit information 4 of the guiding tracks 3 in accordance with the differential signals of the bisected photodetectors.