| 摘要 |
PROBLEM TO BE SOLVED: To obtain a method and device of wavelength measurement capable of measuring the wavelength of coherent light source in wide range by using a reference light. SOLUTION: By using an interference optical system 1 generating an interference pattern by splitting an input light flux in two, giving a specific light path length difference to the obtained two light fluxes and multiplexing them, the reference light from the coherent reference light source 2 with a known wavelengthλ1 is input in the interference optical system 1 and simultaneously the inspecting light from a coherent inspection light source 3 with a known wavelengthλ2 is input in the interference optical system 1 through a different light path. By giving variation of the same quantity to each of the reference light and the inspecting light path length differences in the interference optical system 1, light receiving signals individually obtained for the reference light and the inspecting light are modulated. As the degree of the modulation of the light receiving signals individually obtained for the reference light and the inspecting light are dependent on the wavelengthsλ1 andλ2, the modulation degree of each light receiving signal is detected and compared and the wavelengthλ2 of the inspecting light is calculated from the ratio of them and the wavelength $1 of the reference light.
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