Automatic Recording Absolute Length-Measuring System with Fast Optical-Comb Fiber Interferometer

Abstract

The optical frequency comb has a short pulse, broad spectra, many spectral lines, and high temporal coherency. In this paper, a new absolute length-measuring technique with a high resolution of 0.05 μm is developed by using the temporal-coherence interferometry of the optical comb. A new fiber Fabry-Perot etalon (etalon) of a free spectral range with a frequency of 15 GHz is developed to improve fine positioning in space, so a short translation stage of up to a 10 mm movement is realized for various ranges of length. Moreover, the interference fringe peak is automatically detected by developing a new analog electrical circuit. The ambiguity of the interference-fringe orders is determined by using the etalon at a frequency 14.9 GHz within a time of 1 second for various length ranges.