一种双光梳多外差大尺寸高精度绝对测距新方法的理论分析

摘要

Femtosecond optical frequency comb (FOFC) has been widely used in time-frequency technique and precision spectral mea-surement. The derivative technique for absolute distance measurement by FOFC, which has features of high-speed, large-scale and high-precision, has become a worldwide research hotspot and is promising to be directly applied in some precision ranging missions, such as large equipment manufacturing, satellites formation flying, laser radar and space gravitation measurement, etc. An innovative method for large-scale and high-precision absolute distance measurement based on multi-heterodyne of dual FOFCs, is proposed in this paper. This method combines the multi-heterodyne cross-correlation distance measurement of dual optical combs with the beat-frequency distance measurement based on repetition frequency of the comb, so that it achieves large-scale and high-precision absolute distance measurement without relying on the earlier judgment with time-of-flight measurement, scanning the repetition frequency or scanning the reference beam path. Based on the basic theory of FOFC and the ranging scheme, the theoretical model for large scale distance measurement chain based on dual FOFCs has been constructed;influence of the multi-heterodyne lowest spectral lines and the repetition frequency stability on the measurement results has been discussed, and lots of simulation calculations have been done. Simulation results show that the method has achieved measurement errors better than ±50 pm on the premise of not considering the phase demodulation accuracy, and the impact caused by the deviation of the lowest multi-heterodyne spectrum is figured out to be far below the ranging resolution of the multi-heterodyne measurement, which has verified that the proposed method may be used to realize large-scale and high-precision absolute distance measurement.%　　本文提出了一种双光梳多外差大尺寸高精度绝对测距的新方法,结合基于双光梳互相关的多外差距离测量和基于重复频率的梳间拍频距离测量,在不需要依靠脉冲飞行时间先验判断以及扫描重复频率或扫描参考光路的前提下实现km量程高精度绝对测距。文章在光梳基本原理和测距方案的基础上,建立了基于双光梳的大尺寸距离测量链理论模型,讨论了多外差最低谱线和光梳重复频率稳定度对测量结果的影响,并进行了大量仿真计算；仿真结果表明,在理想相位解调精度的前提下,该方法的测距误差优于±50 pm,且多外差最低谱线的频率偏差对测距造成的影响远低于多外差测量的测距分辨力,验证了该方法能够用于开展大尺寸高精度绝对测距研究。