| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical unit which precisely takes-out only light of a desired wavelength band when changing spectral transmittance characteristic of a desired wavelength region while causing the spectral transmittance characteristic of the other wavelength region to retain the invariable state. SOLUTION: An etalon-type optical element 16 has: a first spectral transmittance characteristic 28A, 28B in a first wavelength band 27; and a second spectral transmittance characteristic 31A, 31B in a second wavelength band 30 of the wavelength side shorter than the first wavelength band 27 with respect to the light made incident to the etalon-type optical element 16 in accordance with a thickness of air layer of the etalon-type optical element, wherein, when the thickness of air layer of the etalon-type optical element 16 is changed between 720 nm (first gap distance) and 520 nm (second gap distance), the first spectral transmittance characteristic 28A, 28B is changed and, on the other hand, the second spectral transmittance characteristic 31A, 31B is substantially invariable. COPYRIGHT: (C)2008,JPO&INPIT
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