| 摘要 |
PURPOSE:To simply inspect the conversion of a band pass filter (BPF) even on the manufacturing line, by radiating a continuous spectral light to the BPF, and photodetecting a passing light by plural photodetecting system whose spectral sensitivity characteristics are different from each other. CONSTITUTION:A light beam from a light source is at least a continuous spectral light in a wavelength area of a range in which it is predicted that a BPF 3 is converted, and its light emission spectral characteristic is flat. The light beam from this light source 1 is projected to the BPF 3 through a condenser lens 2a and a collimator lens 2b, and electric signals from photodetectors 4, 5 whose spectral sensitivity characteristics are different from each other are inputted to an operational amplifier 8 through pre-amplifiers 6, 7. In such a case, when it is assumed that the BPF 3 has the initial spectral transmission characteristic, outputs of the photodetectors 4, 5 are offset to each other so that the output of the operational amplifier 8 goes to '0'. Accordingly, from the output of the operational amplifier 8, whether the center wavelength of the spectral transmission characteristic of the BPF 3 is converted to along wavelength side or is converted to a short wavelength side can be decided.
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