| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical device for an illuminator capable of reducing the unevenness of brightness on a plane without making the illuminator larger in size, and to provide the illuminator. SOLUTION: The optical device for the illuminator is constituted of two diffraction gratings and a reflection layer formed on either surface of parallel plates consisting of transparent resin. The two diffraction gratings have equal spatial frequency to diffract light made perpendicularly incident on the surface in a direction where the light is totally reflected in the parallel plates, one of them is a transmission type diffraction grating and the other is a surface relief type diffraction grating. Then, the reflection layer is formed on the outside of the surface relief type diffraction grating. The optical device for the illuminator constituted in such a way and the illuminator are provided. COPYRIGHT: (C)2005,JPO&NCIPI
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