| 摘要 |
PURPOSE:To reduce the noise generated in a light source by arranging a sensor so that the surface normal of the sensor is inclined to the direction of incidence of a light beam to the sensor. CONSTITUTION:Reflected parallel light beams 21 reflected on a mirror 15 are made incident on the center of a condenser lens 16 in parallel with the optical axis of the lens 16 and are condensed by the lens 16 and are made incident on a sensor 18. The sensor 18 is so arranged that its surface is inclined at an angle theta to a face vertical to the optical axis of the lens 16. Though a part of light beams incident on the sensor 18 is reflected, this reflected light beam 22 is not returned to the side of a semiconductor laser 11 because it goes in the direction inclined at an angle 2theta to incident light beams and is intercepted by a light shielding plate 20. Since the surface of the sensor 18 is a specular surface, there are hardly scattered components of the reflected light. Thus, the occurrence of the noise in the light source is suppressed to improve the precision of optical information recording and reproducing. |
