Experiemental Study Of Interference Method Based On The Femtosecond Laser Frequency Comb Shift

The interference method of femtosecond laser comb is an important basis for optimizing precision measuring instruments and improving measuring accuracy.The interference method based on optical frequency comb not only realizes the unity of length,time and frequency,but also realizes high-tech precision measurement.As a revolutionary breakthrough in the field of laser precision measurement,optical frequency comb pushes the precision measurement technology to a new extreme.Its wide spectrum,high stability and other characteristics make it a powerful tool for precise metrology research,and has pioneering application prospects in time and frequency standard transfer,exoplanet exploration and so on.Therefore,the interference method based on femtosecond laser comb has become the mainstream research object in precision measurement,macro and micro aspects.In view of the important application prospects of femtosecond laser comb,this paper carries out experimental research on the offset,stability and measurement error of femtosecond laser comb.The main research contents are as follows:Chapter 1: The historical background,application and research significance of femtosecond laser comb are introduced.Chapter 2: The principle of femtosecond laser optical frequency comb and its propagation characteristics are analyzed,and the theoretical basis of the influence of dispersion medium in interferometer on its migration is also discussed.Chapter 3: The experimental basis of femtosecond laser comb and the optical frequency comb offset measured in the experiment are introduced.The relative offset frequency is 0.13-0.17 when the offset frequency is within 68-83 MHz.(The experimental basis of this paper is from the University of Siberia).Chapter 4: The influence of the dispersion medium of the interferometer on the optical frequency comb offset of femtosecond laser is simulated and analyzed.The research status in this field at home and abroad is introduced.Based on the related research,theoretical and simulation analysis is carried out.The results show that the statistical error of determining the optical frequency comb offset is 0.01,and the systematic error is 0.1.The basic factors causing statistical errors and systematic errors are the dispersion medium of the interferometer mirror,the curvature of comb wavefront and the alignment of the reflector,the recording of interference fringes,the non-parallel adjustment of the reflector,etc.Chapter 5: The measurement errors caused by comb-front curvature and diffraction divergence of femtosecond laser in absolute distance measurement by interferometry are mainly discussed.Based on the femtosecond laser Gauss beam model,the influence of comb front curvature and diffraction divergence on measurement accuracy is analyzed.The effects of wavefront curvature and diffraction divergence are analyzed by numerical simulation based on the experimental platform composed of femtosecond laser and F-P interferometer.The results show that the measurement error of the detector is the smallest when it is located at the focal point of the reference beam and the maximum curvature of the measured beam.When the measuring mirror moves in a certain range,the systematic error of the interferometer with special points in the above range is the largest,and the measurement error is the smallest.When the waist width of the beam is about 1 mm,the displacement of the interference fringes is the smallest,and the measurement error is the smallest.Chapter 6: Summary and Prospect of this paper.