Video-rate high-precision time-frequency multiplexed 3D coherent ranging

TL;DR

This paper introduces a high-speed 3D imaging system using FMCW LiDAR with a novel combination of beam steering and compressed analysis, achieving video-rate frame rates with high accuracy for dynamic objects.

Contribution

The work presents a new FMCW 3D imaging approach that combines grating-based beam steering and compressed time-frequency analysis for high-speed, high-precision surface imaging.

Findings

Achieves 7.6 MHz depth voxel rate for dense 3D imaging.

Demonstrates submillimeter localization accuracy.

Operates effectively over tens of centimeters range.

Abstract

Recently, there has been growing interest and effort in developing high-speed high-precision 3D imaging technologies for a wide range of industrial, automotive and biomedical applications. Optical frequency-modulated continuous wave (FMCW) light detection and ranging (LiDAR), which shares the same working principle as swept-source optical coherence tomography (SSOCT), is an emerging 3D surface imaging technology that offers higher sensitivity and resolution than conventional time-of-flight (ToF) ranging. Recently, with the development of high-performance swept sources with meter-scale instantaneous coherence lengths, the imaging range of both OCT and FMCW has been significantly improved. However, due to the limited bandwidth of current generation digitizers and the speed limitations of beam steering using mechanical scanners, long range OCT and FMCW typically suffer from a low 3D frame rate (<1Hz), which greatly restricts their applications in imaging dynamic or moving objects. In this work, we report a high-speed FMCW based 3D surface imaging system, combining a grating for beam steering with a compressed time-frequency analysis approach for depth retrieval. We thoroughly investigate the localization accuracy and precision of our system both theoretically and experimentally. Finally, we demonstrate 3D surface imaging results of multiple static and moving objects, including a flexing human hand. The demonstrated technique performs 3D surface imaging with submillimeter localization accuracy over a tens-of-centimeter imaging range with an overall depth voxel acquisition rate of 7.6 MHz, enabling densely sampled 3D surface imaging at video rate.