| 摘要 |
PROBLEM TO BE SOLVED: To propose a focus controller which can be miniaturized. SOLUTION: Reflected light R1 is received at a respectively different extinction ratio through a photodetection surface 31A divided into an extinction whole photodetection area AR1, non photodetection areas AR2 and AR3, and whole photodetection areas AR4 and AR5. A light quantity signal A1a having an S-shaped curve for detecting the deviation of a focal point f1 with respect to the recording surface of a DVD 12 corresponding to a total photo detective light quantity obtained as the result, is outputted. Thus, compared with a conventional focus controller which outputs the light quantity signal by four sheets of photodetector for focus servo, this focus controller obtains the light quantity signal S1a by a single sheet of FS detector 31, thereby miniaturization is realized for the part. COPYRIGHT: (C)2004,JPO
|
