| 摘要 |
PROBLEM TO BE SOLVED: To prevent a laser beam diaphragmed by an aperture diaphragm from being returned to a light source side and erroneously detected in an optical pickup device arranged with the aperture diaphragm on a recording medium side of an objective lens. SOLUTION: The aperture diaphragm 7 is stuck/fixed to the ring like and surface 63 of the recording medium side of the objective lens 6. Since reflection preventing surface treatment is applied to the lens side surface of the aperture diaphragm 7, it is eliminated that the laser beam diaphragmed by the aperture diaphragm 7 is reflected on the lens side surface, and is returned to a light source unit 4 through the objective lens 6, and is converged on a light receiving surface of a photodetector incorporated in the unit 4. Further, since a light transmission part 74 capable of irradiating the annular end surface 63 of the objective lens 6 with parallel light from the recording medium side is formed on the aperture diaphragm 7, the inclined angle of the objective lens can be adjusted based on the reflected beam on the annular end surface 63 without being disturbed by the aperture diaphragm 7. |
