| 摘要 |
PROBLEM TO BE SOLVED: To permit the generation of an excellently accurate tracking error signal without hindering the miniaturization of an optical signal read-out device by the simple constitution. SOLUTION: This optical signal read-out device 1 irradiates the signal recording surface 6a of an optical recording medium 6 with a light beam transmitted from a light emitting element and reads out a signal by detecting the reflected light beam from the signal recording surface by means of a light receiving element. In this case, the device is provided with main light receiving elements 13a, 13b for receiving a light beam from a main light emitting element 15 and a light beam transmitted from the main light emitting element, converged on the signal recording surface in the focused state and reflected thereupon; secondary light receiving elements 14a, 14b for receiving a light beam from a secondary light emitting element 16 and a light beam transmitted from the secondary light emitting element, converged on the signal recording surface in the focused state and reflected thereupon; and an objective lens 3 freely movable in the focusing and tracking directions and converging light beams from the respective light emitting elements on the signal recording surface; and the tracking error signal is generated from the arithmetic outputs between the output signals of respective light receiving elements. |
