| 摘要 |
<p>PURPOSE:To make reflected light from a light collecting reflector into a parallel light beam by a mirror and to improve the utilization efficiency the emitted light of a light source arranged at the focus of the light collecting reflector by arranging a cylindrical mirror in a shape of a frustum of a circular cone on the downstream side of the light source. CONSTITUTION:A cylindrical mirror 10 in the shape of the frustum of the circular cone is provided on the optically downstream side of a metal halide lamp 1 and the light converging reflector 7 consisting of a parabolic mirror and an optical element such as a polarization beam splitter 6 is arranged on the downstream side of them. The mirror 10 is arranged so that its comic surface having the vertex positioned on an optical axis passing the focus of the reflector 7, namely, so that the center axis is aligned with the optical axis. In this case, the mirror 10 is reduced in diameter in the light emission direction. Consequently, the reflected light from the light collecting reflector 7 is further reflected by the mirror 10 to become an effective light beam. Further, even light which is angled too much to the optical axis in the primary reflection of the reflector 7 becomes close to parallel light in the secondary reflection based upon the angle of an external mirror surface 10b.</p> |
