| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device which can detect the focus state of an optical recording medium accurately even if a condensing lens is moved by a tracking operation and, further, even if the diffraction angle of a feedback beam is changed by the wavelength fluctuation of a light source and an optical recording medium driving device equipped with the optical pickup device. SOLUTION: A transmitting hologram device 4 has a quadrant hologram surface 40 which is divided into four regions 4a, 4b, 4c and 4d whose areas are same by imaginery dividing lines 4L and 4M perpendicular to each other. Before a tracking phase is adjusted, the dividing line 4L has an angle θ from the track direction of an optical disc and the dividing line 4M has an angle θfrom the radial direction of the optical disc. After the tracking phase is adjusted, the direction of the dividing line 4L agrees with the track direction of the optical disc and the direction of the dividing line 4M agrees with the radial direction of the optical disc. At the time of a tracking operation, a condensing lens is moved in the radial direction of the optical disc. |
