| 摘要 |
PURPOSE:To increase the quantity of return light to a semiconductor laser positively and also to suppress variation in the quantity of return light to the semiconductor laser by aligning the center of the radius of curvature of the incidence surface closest to a light emission point of the semiconductor laser among incident surfaces of a collimator lens to the light emission point. CONSTITUTION:The incidence surface 13 of a lens 10 closest to the semiconductor laser 1 in the collimator lens 9 is made convex toward the light emission point 14, and the center of the radius r1 of curvature of the incidence surface 13 is aligned to the light emission part 14 of the semiconductor laser 1. Consequently, part of laser light emitted by the semiconductor laser 1 is reflected by the incidence surface 13 to travels back to the light emission point 14 of the semiconductor laser 1 according to the principle of light reflection, so the quantity of return laser light is increased positively. Further, part of laser light which is not utilized as effective luminous flux as to the remaining laser light emitted by the semiconductor laser 1 except the center part is reflected and returned to the light emission point 14 accurately. |
