| 摘要 |
PURPOSE:To prevent the generation of offset based upon autofocusing (AF) and autotracking (AT) control and the generation of a change in the waveform of an AF error signal by providing an optical head with a means for changing the distribution of light intensity in the minimum effective beam out of parallel beams while checking it from the external. CONSTITUTION:When parallel beams projected from a collimeter lens 2 are made incident upon a parallel plane 11, the angle of the plane 11 from the beams is adjusted so that the intensity distribution of beams projected from an aperture 3 determining the minimum effective beam is made symmetrical about the optical axis. In order to check the intensity distribution of the beams projected from the aperture 3, monitor information obtained from an aperture 51 formed on an optical head body is outputted to a waveform monitor as the information of the angular adjustment of the plane 11. The symmetry property of the beams obtained by the angular adjustment of the plane 11 with the ordinary optical axis can be maintained also in a photodetector 10. Consequently, the AF and AT offset to be generated by the optical head can be removed and the waveform change of the AF error signal can be also suppressed. |
