Absolute distance measurement based on spectral interferometer using the effect of the FSR of a Fabry-Perot etalon

摘要

A method for absolute distance measurement is developed here that uses a Fizeau-type spectroscopic interferometer with a Fabry-Perot etalon and a rotating diffraction grating. The integral multiple of the free spectral range (FSR) can be measured using a fiber-type etalon. When the range of length is greater than half of the FSR, the absolute distance can be determined with arbitrary ranges. Moreover, the limited position can be measured over a long distance. Instead of calibrating the wavelength, we use the Fabry-Perot etalon as a standard to determine the absolute position and calibrate the system. Two diffraction gratings increase the spectroscopic resolution to considerably extend the effective range of measurement. Experiments to test the proposed method indicate that it can be used to measure absolute distance with arbitrary ranges of length of up to 120 mm, with repeatability between 0.23 mu m (0.0272%) and 0.77 mu m (0.0619%), and can measure distances up to 1200 mm.