High-precision speed imaging using photon heterodyne detection based on a real-time noise-filtering algorithm

In the actual application of imaging lidar, intensity imaging is difficult to achieve due to the complex environment and weak echo signals. At this time, we can use the vibration difference between the target and the background to image the target and obtain the contour and vibration characteristics of the target. Therefore, as an important means of vibration measurement, the photon-heterodyning imaging system has important value in obtaining the speed of the target. However, due to the impact of shot noise in heterodyne detection, the speed measurement precision of the photon-heterodyning imaging system will decrease. This paper proposes a post-processing algorithm by setting an optimal photon-counting threshold between adjacent pixels to improve the resolution of speed imaging. It can well distinguish between signal and shot noise and suppress shot noise well. The simulation results show that when the intensities of signal light and the local oscillator light are respectively N_S =3 ns^-1, N_L =25 ns^-1 and the selected optimal photon-counting threshold is 6, the speed measurement error is reduced from 6.43 m/s to 0.27 m/s, and the speed measurement precision is increased by 95.8%.