title: Non-Contact Measurement of the Spectral Emissivity through Active/Passive Synergy of CO₂ Laser at 10.6 µm and 102F FTIR (Fourier Transform Infrared) Spectrometer.
abstract: In the inversion of land surface temperature (LST) from satellite data, obtaining the information on land surface emissivity is most challenging. How to solve both the emissivity and the LST from the underdetermined equations for thermal infrared radiation is a hot research topic related to quantitative thermal infrared remote sensing. The academic research and practical applications based on the temperature-emissivity retrieval algorithms show that directly measuring the emissivity of objects at a fixed thermal infrared waveband is an important way to close the underdetermined equations for thermal infrared radiation. Based on the prior research results of both the authors and others, this paper proposes a new approach of obtaining the spectral emissivity of the object at 8-14 µm with a single-band CO₂ laser at 10.6 µm and a 102F FTIR spectrometer. Through experiments, the spectral emissivity of several key samples, including aluminum plate, iron plate, copper plate, marble plate, rubber sheet, and paper board, at 8-14 µm is obtained, and the measured data are basically consistent with the hemispherical emissivity measurement by a Nicolet iS10 FTIR spectrometer for the same objects. For the rough surface of materials, such as marble and rusty iron, the RMSE of emissivity is below 0.05. The differences in the field of view angle and in the measuring direction between the Nicolet FTIR method and the method proposed in the paper, and the heterogeneity in the degree of oxidation, polishing and composition of the samples, are the main reasons for the differences of the emissivities between the two methods.
authors.affiliation: Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China. zhangrh@igsnrr.ac.cn.
authors.forename: Ren-Hua
authors.initials: RH
authors.lastname: Zhang
authors.affiliation: Department of Civil, Environmental and Geomatics Engineering, Florida Atlantic University, Boca Raton, FL 33431, USA. hongbo@ieee.org.
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Su
authors.affiliation: Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China. tianj.04b@igsnrr.ac.cn.
authors.forename: Jing
authors.initials: J
authors.lastname: Tian
authors.affiliation: Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China. misj.12b@igsnrr.ac.cn.|University of Chinese Academy of Sciences, Beijing 100049, China. misj.12b@igsnrr.ac.cn.
authors.forename: Su-Juan
authors.initials: SJ
authors.lastname: Mi
authors.affiliation: Key Laboratory of Agri-informatics, Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China. lizhaoliang@caas.cn.|ICube, UdS, CNRS, 300 Boulevard Sebastien Brant, CS 10413, Illkirch 67412, France. lizhaoliang@caas.cn.
authors.forename: Zhao-Liang
authors.initials: ZL
authors.lastname: Li
keywords: 10.6 µm single-band CO2 laser; active/passive synergistic measurement and inversion; temperature-emissivity retrieval