| 摘要 |
PROBLEM TO BE SOLVED: To provide a new detection optical system which can detect information signals recorded on a disc as well as satisfactory tracking error signals with sufficiently suppressed focus error signals and offset signals by using a simple signal optical system and provide an optical head and an optical information reproducing device on which the detection optical systems are mounted. SOLUTION: A light beam is divided into 5 beams by a halving diffraction lattice 2 and, in addition to a main light spot for the detection of information signals recorded on a disc 7, 2 light spots for the detection of focus error signals and 2 light spots for the detection of the deviation signals of an object lens 6 are applied in defocused states. The disc reflection beams of the light spots are detected by a 12-division photodetector 9. The photoelectric transformation output signals of the 12-division photodetector are subjected to a predetermined operation process to detect the deviation signals of the object lens 6. The deviation signals of the object lens 6 are deducted from push-pull signals detected by the main light spot to reduce offsets included in the push-pull signals, so that satisfactory tracking error signals can be obtained. |
