Phase Unwrapping and Frequency Points Subdivision of the Frequency Sweeping Interferometry Based Absolute Ranging System

Abstract

Frequency sweeping interferometry (FSI) based absolute distance ranging has high precision and no ranging blind area. It can be used to realize large-scale and non-cooperative target measurement. However, the nonlinear frequency modulation of the laser seriously affects the ranging accuracy. In this manuscript, a measurement method assisted by Hilbert Transform (HT) and Chirp-z Transform (CZT) is proposed, which can realize the phase unwrapping of the beat signal, the length reduction in the delay fiber of auxiliary optical path, and the improvement of the frequency resolution. The narrow-band frequency suitable for HT is further studied. In the experiment, the ranging resolution is 70 μm and the standard deviation is 12.6 μm within a distance of 4005 mm.

Enhancement of frequency scanning interferometry signal for non-cooperative target based on generative adversarial network

“…As a high-precision and low-cost absolute distance optical measurement method, frequency scanning interferometry (FSI) is widely used in absolute distance measurement [1][2][3][4][5][6][7][8], geometric accuracy monitoring of large machining centres [9], optical fibre non-destructive testing [10,11], optical coherence tomography [12,13], and light detection and ranging for autonomous driving, as well as other fields [14,15]. In FSI measurement, to obtain high-precision measurement results, a cooperative target mirror is typically used as the point to be measured.…”