A Differential Phase Detection Method for Tracking-Error Signals Using a Monolithic Confocal Laser Coupler

Abstract

We previously presented the differential phase detection method using a monolithic confocal laser coupler with a confocal knife edge structure (the CKE device), which we call the CKE Pit-Edge method and which is applied to an optical disk system in which the disk has a pit depth of λ/4n. In this paper, the experimental results using this new method are reported. The experimental results agree well with the calculated results. Thus, tracking-error signals, which are very stable in the face of radial lens displacement, can be obtained for an optical disk with any pit depth using the CKE Push-Pull method and the CKE Pit-Edge method.