| 摘要 |
PURPOSE: A method for adjusting gratings is provided to remove an error generated in three laser beams disassembled in the gratings by rotating or moving the grating used in an optical pickup. CONSTITUTION: A beam emitted from a first laser diode(31) or a second laser diode(33) is dissembled into a main laser beam and two sub-laser beams by using a first grating(32a) or a second grating(32b). The disassembled beams pass through optical systems used in an optical pickup. A reflective beam reflected from an optical disk(50) is formed on a photo diode of a detector(39). The gratings are rotated or moved forward and backward following an optical axis to focus the main laser beam and the two sub-laser beams reflected from the optical disk to a center four-division photo diode, and upper and lower four-division photo diodes arranged on the detector. |
