To provide a method for measuring the light in the condition that S/N ratio is high and that the influence of the heat to a light detecting unit is small.
In this method for measuring the light, the light to be detected, which is generated from a subject 2 to be checked in the high temperature condition side of a combustion chamber and which has a specified detecting wave length, is led to a light detecting unit 3 for measurement through a wave lenght selecting unit 10 for selectively transmitting the light. In this case, a selective reflecting mirror 7 for reflecting the light to be detected, which is generated from the subject 2 to be checked, to as wave length selecting unit side is deranged on an optical path extended from the subject 2 to be checked to the wave length selecting unit 10, and the light to be detected is led to the light detecting unit 3 for measurement.
HIRANO HIKARI
NISHIGAKI MASASHI
OKAMOTO HIDEKI
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