The research on absolute distance measurement based on large-bandwidth reverse-synchronous dynamic frequency scanning interference

Frequency scanning interferometry is an ideal absolute distance measurement method with high-precision, noncooperative target measurement capability and no blind spot in the measurement. By increasing the sweep bandwidth, high range resolution and accuracy can be achieved, and a higher signal-to-noise ratios of the measurement target can be obtained with the use of heterodyne interferometry technology. The Doppler frequency shift caused by environmental vibration and other factors will reduce the accuracy of the frequency scanned interferometry under realistic conditions. To eliminate the dynamic error caused by the Doppler frequency shift, this paper proposes a large-bandwidth reversesynchronous synchronous frequency scanning interferometry method based on two external cavity tunable lasers. In order to improve the precision of dynamic frequency scanning interferometry, a signal-mixing equal-frequency resampling method is proposed in this paper to simultaneously eliminate the non-linear of the two cavity tunable lasers.The method has been verified through the frequency scanning interferometry analysis of the vibration target and the moving target. This paper compares the accuracy of the proposed method in this paper and the existing method under different signal-to-noise ratios. The results show that the proposed method has higher measuring accuracy than the existing method when measuring the non-cooperative target. For the moving target, this paper proposes a method to complete real-time distance measurement of the target through extracting phase, and the method has been verified through the simulation of the moving target