Absolute distance measurement by spectrally resolved interferometry based on a femtosecond pulse laser

Abstract

A spectrally resolved interferometry ranging method based on the optical frequency comb of a femtosecond pulse laser was presented. The approach utilized a frequency stabilized Ti:sapphire femtosecond pulse laser to provide a phase-locked summation of discrete quasi-monochromatic light modes of consecutive frequencies, which is seen as an optical comb in the frequency domain. In this method all modes interference signals of the optical frequency comb obtained by the femtosecond light pulses traveling along different optical path between the reference and measurement arms were utilized to measure absolute distance. A Fabry-Perot Etalon was used to filter smaller frequency modes from the broad-bandwidth femtosecond laser pulse produced. The actual measured light spectrum of the femtosecond laser source was used as the input data, the whole process of the spectrally resolved interferometry ranging method was simulated through MATLAB. The simulation results indicate that the spectrally resolved interferometry ranging method could satisfy the demand of the small scale measurement with a nonambiguity range of 5.75 mm and an associated resolution of nanometer level.