A Fourier-domain-based line shape recovery method used in direct absorption spectroscopy

Rui Liang; Fupeng Wang; Qingsheng Xue; Qiang Wang; Jinghua Wu; Yaopeng Cheng; Qian Li

doi:10.1016/j.saa.2022.121153

A Fourier-domain-based line shape recovery method used in direct absorption spectroscopy

Spectrochim Acta A Mol Biomol Spectrosc. 2022 Jul 5:275:121153. doi: 10.1016/j.saa.2022.121153. Epub 2022 Mar 14.

Authors

Rui Liang¹, Fupeng Wang², Qingsheng Xue¹, Qiang Wang³, Jinghua Wu¹, Yaopeng Cheng¹, Qian Li¹

Affiliations

¹ College of Information Science and Engineering, Ocean University of China, Qingdao, China.
² College of Information Science and Engineering, Ocean University of China, Qingdao, China; State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun, 130033, China. Electronic address: wfp@ouc.edu.cn.
³ State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun, 130033, China.

PMID: 35305360
DOI: 10.1016/j.saa.2022.121153

Abstract

A novel absorption line shape recovery method with self-calibration function and ultra-easy implementation was introduced to direct absorption spectroscopy (DAS) in this study. The self-calibration function empowered the DAS system with the immunity to the laser power fluctuations. The ultra-easy implementation was achieved in that the DAS system was substantially simplified with a single-path DAS rather than the traditional dual-path differential optical absorption spectroscopy (DOAS), and the absorption profile can be directly recovered by an analog or digital filter instead of complex fitting algorithm or sophisticated balance detection circuits. The reliability and self-calibration characteristic of the new method were validated using CH₄ transition at 1653.72 nm, where the line strength is 1.45×10^-21cm/molec. The Voigt fitting residual and signal to noise ratio were optimized in detail and compared with the DOAS.

Keywords: Direct absorption spectroscopy; Fourier domain; Line shape recovery; Self-calibration; Sinewave scanning.