Research on rough surface heterodyne detection signal and scattered beat signal

Abstract

The application of optical heterodyne detection is very demanding, and the roughness of target surface will seriously affect the echo heterodyne detection. In the study of electromagnetic scattering of rough target, Kirchhoff approximation method (KA) is suitable for studying the situation of small rough surface fluctuation. Through studying the laser scattering characteristics of target surface, it can be found that it plays an important role in the extraction of rough target characteristics, detection and acquisition of target echo data. Based on the experimental theory and electromagnetic scattering theory, this paper explores the influence and rule of rough surface on detection, verifies the correctness and feasibility of experimental theory by comparing and analyzing the results. It can be seen from the simulation results of heterodyne echo phase difference that the distortion in front of the detection return wave and the "decoherence" effect of intermediate frequency signal are mainly caused by the root mean square height and correlation length of rough surface. Simulation results based on the two theories show that, with the increase of roughness, the two signal values decrease sharply and then tend to zero; with the increase of correlation length, the two signal values increase first and then tend to be stable. The correctness and feasibility of heterodyne experiment theory are verified by comparing and analyzing the two simulation results.