A 10-nm Spectral Resolution Hyperspectral LiDAR System Based on an Acousto-Optic Tunable Filter.

Yuwei Chen,Juha Hyyppä,Changhui Jiang,Chuanrong Li,Fanrong Meng,Wei Li,Eetu Puttonen,Lingli Tang,Ning Wang

doi:10.3390/s19071620

Abstract

Hyperspectral LiDAR (HSL) technology can obtain spectral and ranging information from targets by processing the recorded waveforms and measuring the time of flight (ToF). With the development of the supercontinuum laser (SCL), it is technically easier to develop an active hyperspectral LiDAR system that can simultaneously collect both spatial information and extensive spectral information from targets. Compared with traditional LiDAR technology, which can only obtain range and intensity information at the selected spectral wavelengths, HSL detection technology has demonstrated its potential and adaptability for various quantitative applications from its spectrally resolved waveforms. However, with most previous HSLs, the collected spectral information is discrete, and such information might be insufficient and restrict the further applicability of the HSLs. In this paper, a tunable HSL technology using an acousto-optic tunable filter (AOTF) as a spectroscopic device was proposed, designed, and tested to address this issue. Both the general range precision and the accuracy of the spectral measurement were evaluated. By tuning the spectroscopic device in the time dimension, the proposed AOTF-HSL could achieve backscattered echo with continuous coverage of the full spectrum of 500–1000 nm, which had the unique characteristics of a continuous spectrum in the visible and near infrared (VNIR) regions with 10 nm spectral resolution. Yellow and green leaves from four plants (aloe, dracaena, balata, and radermachera) were measured using the AOTF-HSL to assess its feasibility in agriculture application. The spectral profiles measured by a standard spectrometer (SVC© HR-1024) were used as a reference for evaluating the measurements of the AOTF-HSL. The difference between the spectral measurements collected from active and passive instruments was minor. The comparison results show that the AOTF-based consecutive and high spectral resolution HSL was effective for this application.

Highlights

The concept of hyperspectral LiDAR (HSL) emerged at the beginning of this century [1], combining the active hyperspectral imaging technique and LiDAR distance measuring technique into a single instrumental framework with fine spectral resolution
These researches supported the conclusion that fusion of the spatial information from active LiDAR and the spectral images from the passive imager presented better performance than the methods based on any single sensor [6,7,8]
This paper proposes, designs, and tests a tunable HSL technology based on an acousto-optic tunable filter (AOTF) device known as AOTF-HSL

Summary

Introduction

The concept of hyperspectral LiDAR (HSL) emerged at the beginning of this century [1], combining the active hyperspectral imaging technique and LiDAR distance measuring technique into a single instrumental framework with fine spectral resolution. Point clouds collected by active LiDAR fused with spectral images collected by passive imaging spectrometry have been extensively investigated for various research purposes, such as forest inventory, land classification, and mineral identification. These researches supported the conclusion that fusion of the spatial information from active LiDAR and the spectral images from the passive imager presented better performance than the methods based on any single sensor [6,7,8]. The Academy of Opto-Electronics (AOE), Chinese Academy of Sciences (CAS), proposed a scheme that combined the monochrome laser source based pushbroom-style LiDAR and the spectrometric imaging sensor by sharing an optical system to quickly generate 3D spectral images [9,10]

Methods

Results

Conclusion