A Monolithic Confocal Laser Coupler For an Optical Pick-up

Abstract

We propose a novel optical pick-up using a confocal laser coupler for an optical disk player. The laser coupler consists of a glass window and a monolithic optical element which includes a laser diode, 8 photodiodes, and a pyramid-shaped prism mirror positioned near the confocal plane which acts as a knife edge and a photo-coupler. The focusing-error signal is detected using the confocal knife edge (CKE) method and the tracking-error signal is detected using the CKE push-pull method. The jitter of Compact Disc (CD) readout was 6.7 ns at a line velocity of 1.2 m/s, and the DC offsets of the tracking-error signal were sppressed to less than 1/3 for a radial lens displacement of ±400 µm compared to the conventional push-pull method.