Overall Non-Mechanical Spectrally Steered LiDAR Using Chirped Amplitude-Modulated Phase-Shift Method

Zheyuan Zhang,Sze Y Set,Takuma Shirahata,Shinji Yamashita,Chao Zhang

doi:10.1109/jlt.2021.3131027

Abstract

We propose and demonstrate an overall non-mechanical spectrally steered laser rangefinder using the dispersion-tuned swept laser (DTSL) and a passive diffractive element. The DTSL has no mechanical moving parts, making it possible to achieve an inertial-free high wavelength sweeping speed. The inherent intensity-modulation characteristic of the DTSL allows the modulation phase-shift method to be applied, similar to that used for an amplitude-modulated continuous-wave (AMCW) rangefinder. Since the pulse repetition rate of the DTSL is chirped, standard signal processing techniques for AMCW are not applicable. In this paper, we propose a novel chirped amplitude-modulated phase-shift (CAMPS) method with a signal processing technique to obtain the phase-shift information from a chirped amplitude-modulated signal. As a proof of concept, we demonstrated the CAMPS LiDAR with an axial ranging resolution of ~50 m at a scanning speed of 10 kHz.

Highlights

Laser detection and ranging (LiDAR) is a laser-based technology for distance measurement with the reflected light from the object under measurement [1], [2]
We propose a novel method called the chirped amplitude-modulated phase-shift (CAMPS) method, which allows the acquisition of distance information from the phase-shift measurement of the chirped amplitude-modulated signal from the dispersion-tuned swept laser (DTSL)
In the CAMPS methods, all the higherorder frequency components will be filtered out so that the pulse shape will not affect the performance of the system

Summary

Introduction

Laser detection and ranging (LiDAR) is a laser-based technology for distance measurement with the reflected light from the object under measurement [1], [2]. Most of the current LiDAR systems are based on optical elements driven by electromechanical devices, such as galvo scanners [12], polygon mirrors [13], Risley prisms [14], [15], or Microelectromechanical systems (MEMS) [16], [17]. These mechanical devices have limited steering speeds due to inertia, and are usually costly, bulky, Zheyuan Zhang, Takuma Shirahata, Shinji Yamashita, and Sze Y. Set are with Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8904, Tokyo, Japan

Methods

Results

Conclusion