A monolithic confocal laser coupler for an optical pick-up

We propose a novel optical pick-up using a confocal laser coupler for an op tical disk player. The laser coupler consists of a glass window and a monol ithic optical element which includes a laser diode, 8 photodiodes, and a py ramid-shaped prism mirror positioned near the confocal plane which acts as a knife edge and a photo-coupler. The focusing-error signal is detected usi ng the confocal knife edge (CKE) method and the tracking-error signal is de tected using the CKE push-pull method. The jitter of Compact Disc (CD) read out was 6.7 ns at a line velocity of 1.2 mis, and the DC offsets of the tra cking-error signal were sppressed to less than 1/3 for a radial lens displa cement of +/-400 mu m compared to the conventional push-pull method.