| 摘要 |
PROBLEM TO BE SOLVED: To convert substantially whole energy of a light beam formed in a light source to required linear polarization and to minimize the light loss by constituting so that all points on a mirror cross an optical path of one beam in a reflection beam. SOLUTION: In a reflection type polarizing element 42a, the position of a light convergent element 41a on an optical axis is set so that beams in circularly polarized components reflected by the reflection type polarizing element 42a are made incident on respective points on the reflection surface of the mirror 43. The reflection type polarizing element 42a is formed on a position that when the focal distance of the light convergent element 41a on the optical axis is defined (f), the distance from the focus F of the light convergent element 41a is nearly f/2 or below, further concretely, the distance from the focus F is nearly f/4. Since the position and the size of the reflection type polarizing element 42a are decided in such a manner, the position of the mirror 43 is decided also to the position shifted from the focus F toward a light convergent member 41 by the distance of nearly 3f/4 on the axis parallel to the optical axis. Thus, all points on the mirror 43 cross the optical path of one beam in the reflection beam. |
