| 摘要 |
PROBLEM TO BE SOLVED: To provide techniques to suppress light reflection or astigmatism in a polarization separating unit and to maintain high picture quality of an image in projection type image display techniques. SOLUTION: This polarization separating body to be used in the polarization separating unit is configured by disposing a polarization separating plane which separates polarized light by diffraction based on a grating structure, in contact with a light transmissive medium between prism materials. Further, the polarization separating plane is formed of a light reflective grating member arranged into a grating on a light transmissive substrate. The medium or the substrate used satisfies ä(n<SB>2</SB>-n<SB>1</SB>)/(n<SB>2</SB>+n<SB>1</SB>)}<SP>2</SP>≤0.003, wherein n<SB>1</SB>and n<SB>2</SB>are refractive indices of the medium and the substrate, respectively. COPYRIGHT: (C)2007,JPO&INPIT
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