| 摘要 |
PURPOSE:To easily and exactly adjust a rotational position of a grating lens by detecting a phase of a variation signal of an optical intensity distribution generated by intersecting the respective information tracks of a main beam which is made incident on a photodetector, and a tracking error signal generating sub-beam. CONSTITUTION:Reflected light beams from one piece of main beam MB and two pieces of sub-beams SBe, SBf radiated to information tracks T1-T3 of an optical disk are detected by photodetectors A-F. In this case, the detectors A-D are four split elements to the main beam MB, and the detectors E, F are elements to the sub-beams SBe, SBf. Subsequently, at the time of detecting the direction of the beam by using these detectors, outputs of the detectors A-D are brought to a phase detection by a phase comparator 16 through an operation and current/voltage transducer 15, outputs of the detectors E, F are inputted to computing elements 11, 12 through current/voltage transducers 10, 13, respectively and a result of the detectors A-D, and a result of E and F are displayed on an indicator 17, and an indicator 14, respectively. |
