OPTICAL PHASE MEASURING APPARATUS, OPTICAL PHASE MEASURING METHOD AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide an optical phase measuring apparatus for performing measurement using a phase shift amount of a measurement object even when there is limitation in phase setting accuracy of reference light.

SOLUTION: The optical phase measuring apparatus includes an optical interferometer composed of: a coherent light source 81; light branching means 82 for branching a light wave from the light source 81 into two light waves; phase modulation means 83a for phase-modulating a reference light wave 89 out of the branched light waves by a frequency ωm; photosynthesis means 97 for synthesizing a signal light wave transmitted or reflected through/by a measurement object 85 after being branched and the phase-modulated reference light wave 89; and light intensity measurement means 88 for measuring the intensity of synthesized interference light. The optical phase measuring apparatus further includes arithmetic means 95 which acquires the intensity of interference light over a fixed time, Fourier-transforms acquired time-sequential intensity signals, calculates light intensity values of at least two components out of frequency components corresponding to integer times of the phase modulation frequency ωm, identifies a modulation index m of the phase modulation means 83a, and calculates phase variation ϕ of the signal light waves by the measurement object 85 based on the modulation index m.

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