Design of skewed fitting algorithm for off-axis integrated cavity output spectroscopy
Aims:This study aims to investigate the issue of skewed absorption spectra caused by fast laser scanning in off-axis integrated cavity output spectroscopy(OA-ICOS)and address the limitations of traditional linear fitting functions,which result in large fitting errors and low measurement accuracy.Methods:This paper presents a skewed fitting algorithm based on OA-ICOS to improve the measurement accuracy by fitting the skewed absorption spectra.The algorithm analyzes the causes of spectral skewness based on the principles of OA-ICOS and incorporates the skewed characteristics using the Voigt line shape function to obtain a fitting function with the skewness factor.Results:In the experiments,with laser scanning frequencies set at 50 Hz,150 Hz,and 300 Hz,the deviations of the absorption peak positions obtained by the Voigt fitting algorithm were 4 × 10-3 cm-1,4.8× 10-3 cm-1,and 6.2× 10-3 cm-1,respectively.However,using the skewed fitting algorithm,the deviations of the absorption peak positions were only around 2.4×10-3 cm-1,2.4× 10-3 cm-1,and 1.5×10-3 cm-1,respectively.Conclusions:This method can accurately fit the skewed absorption spectra signals under fast laser scanning frequencies,thereby improving the fitting accuracy.
integrated cavity output spectroscopy(ICOS)off-axis incidenceskewing effectspectral line skewnessfast laser scanning frequency
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