METHODS AND SYSTEMS FOR MEASURING MICRODISIA USING A SINGLE-FREQUENCY INTERFERENCE METER WITH PERIODIC NON-LINEAR ERROR COMPENSATION UTILIZING GEOMETRICALLY NORMALIZED CROSS-DIFFERENTIAL DEMODULATION

Abstract

The invention relates to a method and system for measuring micro-displacement based on a single-frequency interferometer with periodic nonlinear error compensation using geometrically normalized cross-differential demodulation. The system comprises a laser source 1, an interferometric array creating a measurement and reference branch, an optical sensor 11, an even and odd harmonic signal pair extractor 14, a clean phase signal extractor 15, a signal processor 16, and a harmonic signal generator 17. The interferometric signal is converted into an electrical signal, extracted as an even and odd harmonic signal pair, and then geometrically normalized to compensate for the DC offset, amplitude deviation, and phase angle deviation. The normalized signal pair is demodulated by algebraic cross-differentials to create a clean phase, thereby determining the displacement and quantifying the periodic nonlinear error.

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