Multi-mode Coherent Detection Ghost Imaging Lidar and Vibration-Mode Imaging

TL;DR

This work addresses phase-resolved lidar imaging in environments with multi-mode reflections by marrying ghost imaging with coherent detection in a bucket-detector CD-GI lidar. By coherently mixing reflected multi-mode fields with a single-mode LO at a bucket detector and exploiting field correlation, it decouples multi-mode contributions and enables reconstruction of both amplitude and phase, as well as spatial distributions of target vibration modes. The authors develop a theoretical framework and validate it experimentally, showing static target imaging, IF-energy behavior consistent with detector-area dependencies, and the ability to reconstruct micro-Doppler vibration modes and three-dimensional target information. The approach reduces the spatiotemporal bandwidth requirements compared with coherent focal-plane arrays and holds promise for applications in autonomous sensing, non-contact structural health monitoring, and precise vibration measurements, thanks to complex-reflectivity imaging and dynamic-mode localization achieved with a single detector.

Abstract

Coherent detection ghost imaging lidar (CD-GI lidar) integrates ghost imaging with coherent detection, thereby achieving enhanced anti-interference and phase-resolved imaging capability. Here, we propose a bucket-detector-based multi-mode coherent detection scheme for CD-GI lidar, where the reflected multi-mode light fields are coherently mixed with a single-mode local oscillator (LO) at the bucket detector photosensitive plane. The bucket-detector-based multi-mode CD-GI lidar system breaks the constraints of Siegman antenna theorem by utilizing field correlation to decouple the reflected multi-mode light fields and reconstructs the spatial distribution of targets' vibration modes. Theoretical analysis of the bucket-detector-based multi-mode CD-GI lidar system is presented in this work, and its feasibility is verified through a series of experiments.

Figures (7)

• Figure 1: Schematic of the bucket-detector-based multi-mode CD-GI lidar system.
• Figure 2: Experimental setup of the bucket-detector-based multi-mode CD-GI lidar system.
• Figure 3: The reconstructed image of amplitude and phase reconstructions for rough and smooth targets. (1.a) Amplitude and (1.b) phase images of the rough target, whose ground truth object is shown in (1.c). (2.a) Amplitude and (2.b) phase images of the smooth target, with the corresponding object shown in (2.c). The smooth target exhibits a clear deterministic phase distribution, whereas the rough target produces a spatially random phase. (2.d) One-dimensional phase profile extracted from the highlighted region in (2.b).
• Figure 4: IF signal energy and the total energy of all reconstructed pixels versus the receiving aperture variation range under different detector diameters (simulation and experiment). (1.a)-(1.c) Detector size: 300 $\mu$m, 200 $\mu$m, 100 $\mu$m. (2.a)-(2.b) Detector size: 300 $\mu$m, 200 $\mu$m.
• Figure 5: Experimental results of spatial vibration mode reconstruction of the vibrating target: (a) simplified schematic of one vibrating target setup; (b) vibration frequency of 1000 Hz; (c) vibration frequency of 2000 Hz.