OPTICAL HEAD DEVICE AND OPTICAL INFORMATION PROCESSOR

摘要

A laser beam (32) reflected by an information layer of a multilayer optical disc (26) is reflected and split by reflecting planes (31a', 31b, 31c, 31d), and enters a photodetector element (36) as laser beams (33, 34, 35). The laser beam (34) is collected to a light receiving region (38) for RF detection, and an RF signal is generated. The laser beams (33, 35) enter light receiving regions (37a, 37b) for focus detection, and a focus error signal is generated by an SSD method. A laser beam (65) reflected by an information layer adjacent to the information layer partially passes through the reflecting plane (31a'), is focused on a light receiving region (66) for tracking detection, and a tracking error signal is generated.