| 摘要 |
PURPOSE:To compensate mutually variation in angle of reflection with wavelength and hold an angle of projection constant, and also compensate a position shift with temperature by using plural prisms made of different materials, and composing a housing of plural members made of different materials. CONSTITUTION:A coupling lens 12 for collimating a beam from a semiconductor laser 11 into a parallel beam is composed of a combination lens formed by combining various kinds of convex lens and concave lens of different materials in order to eliminate chromatic abberation. A beam width conversion optical system 13 which converts an elliptic parallel beam from the coupling lens 12 into a parallel beam with a circular or pseudo-circular distribution consists of a compound prisms formed by coupling at least two kinds of prism made of a material differing in the wavelength dispersion of a refractive index. The housing 14 consists of the 1st cylinder 14A which supports the semiconductor lens 11 fixedly and the 2nd cylinder 14B which supports the compound prism 13 fixedly, and they are made of materials having different coefficients of thermal expansion. |
