A method for displacement measurement based on reciprocal interferometry with spectrum analysis techniques

摘要

A nanometer range displacement measurement system is presented where a reciprocal interferometer is employed whose configuration is similar to Michelson interferometer. Although the reciprocal interferometer is very simple and insensitive to environmental perturbations, we concluded that the spectrum analysis techniques could also be used to process the interference fringes and increase the measurement precision of reciprocal interferometry. Fast-Fourier transform and filter are used to eliminate the noises in fringes. The reconstructed fringes are very clear, which location can be measured accurately. Theoretical analysis is presented. Experimentally, the displacement of a nanopositioner-driven target was measured by using a reciprocal interferometer, a CCD camera, picture card and computer. The system has demonstrated a minimum resolution is 1.5 nm when the number of sample point is 512.