OPTICAL SYSTEM FOR GUIDING THE READ-OUT BEAM IN A MAGNETO-OPTICAL MEMORY

摘要

An optical system for guiding a read beam and a magneto-optical storage which utilizes a single beam splitter inserted in the beam path of a linearly polarized light beam directed onto a storage disk for splitting the reflected beam into a deflected beam path and onto photo detectors. This optical arrangement includes a polarizer and an astigmatic imaging system. One of the two photo detectors is a four-quadrant detector and the other of the two detectors can be split into two regions with each of these detectors being positioned in one of the two sub-beams. Data signals derived from the intensity differences between the sub-beams and control signals for both a focusing control and for tracking control are derived from the detectors. Preferably, the photo detectors and the integrated circuits are part of an integrated circuit which also includes electrical circuits for the arrangements for obtaining the raw data, the tracking signal and the focusing signal.