| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical device masking a whole device simple and small, capable of stably obtaining a tracking signal to optical recording media having a variety of pit depths and easily manufacturing the device by a semiconductor process. SOLUTION: This device comprises an irradiated part 2 forming a pit on its reflection surface, a semiconductor part 7 in which a semiconductor laser LD, a semiconductor structure 4 and a photodetector element PD are formed on the same semiconductor substrate 1 and a converging means 3 irradiating the irradiated part with a transmitted light beam LF from the semiconductor laser LD so that the beam is made to be coverged, and converging the reflected light bream LR. The semiconductor structure 4 has three reflection surfaces M1 , M2 , M3 , the photodetector element has a first detector element PDR receiving the returned light on the second reflection surface M2 and a second detector element PDL receiving the returned light on the third reflection surface M3 , a first detection signal in the first detector element and a second detecting signal in the second detector element are obtained from the diffracted light from one pit edge of a pit and a tracking error signal TE is obtained by calculating the first and second detecting signals. |
