OPTICAL PICKUP

摘要

PROBLEM TO BE SOLVED: To provide an optical pickup necessary for an optical disk system capable of recording/reproducing and having high density and a high transfer rate by using a short wavelength light source of about several mW. SOLUTION: Blue light transmitted from a SHG blue laser 1 is converted into parallel light by means of a collimator lens 2. After transmitting through a polarizing beam splitter 3 and a quarter wavelength plate 4, the blue light beam made a parallel beam is introduced to an optical disk 6 by an objective lens 5. A signal light beam reflected on the optical disk 6 is bent by 90 deg. by the polarizing beam splitter 3, transmitted through a detecting lens 7 and a cylindrical lens 8 and introduced to a photodetector 9 composed of an avalanche photodiode (APD). The photodetector 9 has a quatripartite structure.