Analysis of an innovative method for large-scale high-precision absolute distance measurement based on multi-heterodyne interference of dual optical frequency combs

Abstract

Femtosecond optical frequency comb (FOFC) has been widely used in time-frequency technique and precision spectral measurement. 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.