Tracking control for optical head - uses two sensors to monitor laser beam and control position

摘要

The output of a laser (1) is directed onto a beam splitter (2) that directs the output to a lens (4) for focussing onto the surface of a disc (5) with formed information tracks (T). The beam passes through an aperture plate (30) having sensors (31,32) formed at the edges. The sensors are semicircular and provide signals that are compared (40). The difference signal is used to control the signal generator (7) for the head controller (9) to adjust the position of the lens. ADVANTAGE - High stability.