OPTICAL INFORMATION PROCESSOR

摘要

PURPOSE:To prevent a track error signal from mixing with a focus error signal at the time when an optical head is placed on a line due to parallel movement of the center line of an optical disk by providing an image rotating element in the optical path from an objective lens to a photodetector in an optical head and providing a rotating means which rotates this image rotating element. CONSTITUTION:An optical head 31 is so driven and controlled that an objective lens 7 of the optical head 31 is moved on a line due to parallel movement of the center line of an optical disk 30. An image rotating element 32 is provided in the optical path from the objective lens 7 to photodetectors 12 and 14. A rotating means 33 rotates and controls the image rotating element 32 in such direction in accordance with the relative position of the optical head 31 to the optical disk 30 that rotation of diffracted images on photodetectors 12 and 14 is cancelled. Thus, the track error signal is prevented from being mixed with the focus error signal because rotation of diffracted images on photodetectors 12 and 14 of the optical head 31 moved on the line due to parallel movement of the disk center line is cancelled.