Long-term repeatability improvement using beam intensity distribution for laser-induced breakdown spectroscopy

Jiacen Liu; Weiran Song; Weilun Gu; Zongyu Hou; Kaikai Kou; Zhe Wang

doi:10.1016/j.aca.2023.341004

Long-term repeatability improvement using beam intensity distribution for laser-induced breakdown spectroscopy

Anal Chim Acta. 2023 Apr 22:1251:341004. doi: 10.1016/j.aca.2023.341004. Epub 2023 Feb 22.

Authors

Jiacen Liu¹, Weiran Song¹, Weilun Gu¹, Zongyu Hou², Kaikai Kou¹, Zhe Wang³

Affiliations

¹ State Key Laboratory of Power System Operation and Control, International Joint Laboratory on Low Carbon Clean Energy Innovation, Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China.
² State Key Laboratory of Power System Operation and Control, International Joint Laboratory on Low Carbon Clean Energy Innovation, Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China; Shanxi Research Institute for Clean Energy, Tsinghua University, Shanxi, 030032, China.
³ State Key Laboratory of Power System Operation and Control, International Joint Laboratory on Low Carbon Clean Energy Innovation, Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China; Shanxi Research Institute for Clean Energy, Tsinghua University, Shanxi, 030032, China. Electronic address: zhewang@tsinghua.edu.cn.

PMID: 36925309
DOI: 10.1016/j.aca.2023.341004

Abstract

The relatively low measurement repeatability has long been considered as a major obstacle to the widespread use and commercialization of laser-induced breakdown spectroscopy (LIBS). Although many efforts have been made to improve the signal repeatability in the short term, how to improve the long-term signal repeatability is critical in practical applications and has rarely been studied. Moreover, the mechanisms behind the degradation of long-term repeatability are not fully revealed. This study proposes a new method to improve the long-term repeatability of LIBS measurement, which modifies the spectral intensity based on laser beam intensity distribution. It first pre-processes the beam intensity distribution profiles and spectral intensity. Then the relationship between the relative deviations of beam and spectral intensities is modelled using Partial Least Squares Regression (PLSR). The proposed method was tested on copper and silicon samples, and the spectra and laser beam intensity distribution were recorded for more than thirty days. Day-to-day variations in beam intensity distribution were observed. Such variations can lead to changes in spectral intensity, resulting in degraded signal repeatability. By modifying the spectral intensity, the long-term signal repeatability was improved. Specifically, in terms of day-mean spectral intensity, the valid correction rates were above 70% for both of copper silicon sample in most cases. Long-term RSD decreased from ∼13.5% to ∼4% for copper and decreased from ∼10.7% to 6.5% for silicon sample. These results indicate that the proposed method provides a viable method for improving the long-term repeatability of LIBS measurement.

Keywords: Beam intensity distribution; Beam profile; Laser-induced breakdown spectroscopy; Long-term repeatability; Signal correction.