| 摘要 |
PROBLEM TO BE SOLVED: To facilitate design of characteristics of an optical filter.SOLUTION: An etalon filter 300 includes a first substrate 20, a second substrate 30 facing the first substrate, a first optical film 40 provided to the first substrate, and a second optical film 50 provided to the second substrate to face the first optical film. A reflection characteristic L1 determined by the reflectivity of light of each wavelength in a reflection band in the first optical film 40 is different from a reflection characteristic L2 determined by the reflectivity of light of each wavelength in a reflection band in the second optical film 50. The optical film 40 can have a reflection characteristic where a first wavelength λ1 is a center wavelength, and the second optical film 50 can have a reflection characteristic where a second wavelength λ2 different from the first wavelength is a center wavelength. The optical films 40 and 50 are so designed that the relation of λ1<λ3<λ2 is established, where a center wavelength in a spectral band of the etalon filter 300 is λ3. |
