OPTICAL ELEMENT, OPTICAL HEAD AND OPTICAL INFORMATION PROCESSOR

摘要

A light beam reflected off an information medium is split, by means of a diffraction optical system, into a first diffracted light and a second diffracted light which is not the complex conjugate wave of the first diffracted light at a specified energy distribution ratio. The first diffracted light is directed to a first photodetector (195) and used for reading out data information recorded on the information medium while the second diffracted light is directed to second and third photodetector (194, 195) and used for obtaining a servo error signal. Since the area of the first photodetector in an optical head can be decreased, a data signal can be reproduced at a high rate. Furthermore, the first photodetector is insusceptible to stray light and S/N ratio is enhanced because the number of head amplifiers required for data signal detection is decreased.