| 摘要 |
PROBLEM TO BE SOLVED: To simplify and miniaturize a collimate optical system by constituting the collimate lens with a single lens and satisfying a specified condition. SOLUTION: This collimate lens system consists of a collimate lens 1, a beam splitter 2 for dividing light form a light source, a cover glass 3 of a semiconductor laser 4 and the semiconductor laser 4 from a parallel luminous flux emission side. A light beam outgoing from the semiconductor laser 4 transmits through the cover glass 3 and the beam splitter 2 to become parallel light by the collimate lens 1. The collimate lens 1 is a positive meniscus single lens and satisfies the equation, d/(2.NA.f)>=0.5. Where NA shows a lens numerical aperture, (d) shows the thickness of the lens and (f) shows the focal distance of the lens. Since the collimate lens 1 constituted in such a manner become a meniscus form, a distance from the semiconductor laser 4 to the collimate lens 1 is shortened and the miniaturization of an optical head device is attained. |
