| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a lighting optical system for a projection type display device capable of realizing various illuminance distribution corresponding to purposes of devices without lowering the utilizing efficiency of the light. SOLUTION: This lighting optical system has a light source lamp 1, a light mixing element 3 mixing the rays of light emitted from the light source lamp 1, a DMD (digital micromirror device) element 5 having a plurality of pixels, a transfer optical system 4 making the light-emitting end face 3a of the light mixing element 3 and a surface to be illuminated 5s of the DMD element 5 to be in an optically conjugate relation and a field lens 6 which is arranged in the front of the element 5. The focal length of the field lens 6 is changed so that illuminance distribution which is decided in accordance with the purpose of the lighting optical system can be obtained on the surface to be illuminated 5s.</p> |
