| 摘要 |
An optical-pickup apparatus includes: a laser diode; an objective lens; a diffraction grating; a photodetector including main-beam-, first-sub-beam-, and second-sub-beam-light-receiving portions; a quarter-wave plate having either a second area allowing a reflected-laser beam to pass therethrough without polarization or a third area allowing the reflected beam to pass therethrough at a polarization angle different from that of the first area; and a polarizing member having a separate-light-amount ratio set therefor with respect to the reflected beams passing through the second or third area and an area excluding the second or third area from the first area, such that proportions of the reflected beams passing therethrough toward the photodetector are different, thereby decreasing an irradiation level when the first- and second-sub-beam-light-receiving portions are irradiated, as stray light, with the reflected beam reflected from either one, not subjected to a signal-reading operation, of the first- and second-signal-recording layers of an optical disc. |
