Frequency-domain Interference For Absolute Distance Measurement Using A Femtosecond Optical Frequency Comb

Length is always stepping along with the progress of human society. In 1971, the 14 th CGPM ruled length one of the seven basic physical quantities. As people's requirement of length measurement is increasing, definition of meter is also developing, relevantly. How to realize a higher measurement precision, a larger scale of measurement, and a more rapid measurement speed is particularly important. The emergence of femtosecond optical frequency comb(FOFC) provides breakthroughs for distance measurement technology. Frequency domain interference of FOFC has an important application in the field of laser absolute distance measurement technology. In this paper, a method of frequency domain peak-to-peak interval based on Fourier transform is proposed.The main works in this paper include the following several aspects:(1)Application and research situation of FOFC were studied. Illustrated the time domain and frequency domain characteristics of FOFC and analyzed the characteristics of FOFC.(2)Analyzed the principle of measurement system of frequency domain peak-to-peak interval and formula derivation. Analyzed the three critical indexes of the system, and pointed out that the system has an infinity measurement limit, theoretically. Set up the experimental system. Carried out the distance measurement experiments and gave experimental results.(3) Proposed an improved phase slope data processing method based on complex wavelet transform, and introduced the principle and advantages of this method. Analyzed the experimental data processing.(4) A comparison experiment using continuous-wave interferometer and classical Fourier analysis method was carried out. Continuous-wave interferometer has a high ranging accuracy and with its measurement data, we evaluated our experimental data. Studied the classical Fourier analysis method of data processing and found out that different window has different effects on the result. A numerical simulation of the simulation data and a data processing of experimental data from the spectrometer were proposed.(5) Analyzed the experiment data and error evaluation. Experiment results show that the results of frequency domain peak-to-peak interval method are better than that of phase slope data processing method, in generally. But when the measured distance is quite short, phase slope data processing method performs better.