| 摘要 |
PROBLEM TO BE SOLVED: To provide a flame sensor whose wave sensitivity is controlled. SOLUTION: The flame sensor 20 comprises a filter device 22 constituted by arranging a plurality of filter means 11 and 12 in series with duplication in the progression direction of incidence light, and a photoreceiver 21. In the transmissivity spectrum of synthesized light by a plurality of filter means 11 and 12, the first transmissivity in a detection objective wavelength range is larger than the second transmissivity in a shield wavelength range in longer wavelength side than the detection objective wavelength range. Also, the first sensitivity value in the specific first wavelength in the detection objective wavelength range is in the shield wavelength range and is 10,000 times or more of the value in the second sensitivity in the second wavelength which is longer by 50 nm than the first wavelength.
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