[OPTICAL REVIEW Vol. 6, No. 4 (1999) 308-313]

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

Takeshi MIZUNO and Hironobu NARUI

Research Center, Sony Corporation, 2-1-1, Shinsakuragaoka, Hodogaya-ku, Yokohama, Kanagawa, 240-0036 Japan

(Received February 8, 1999; Accepted April 5, 1999)

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.

Key words : optical memories, optical pick-up, tracking-error signal detection, confocal optics, GaAs laser diode, GaAs photodiode