An accurate algorithm for calibration-free wavelength modulation spectroscopy based on even-order harmonics

TL;DR

This paper introduces a precise, calibration-free wavelength modulation spectroscopy algorithm utilizing even-order harmonics, based on an improved Voigt function model, achieving rapid measurements and broad applicability with high accuracy.

Contribution

The paper presents a novel, analytically derived algorithm that enhances wavelength modulation spectroscopy accuracy and speed without the need for calibration, based on an advanced line-shape model.

Findings

Achieves gas temperature measurement with less than 2.4% relative error.

Enables measurement speeds down to milliseconds.

Demonstrates broad applicability across different line-shape broadening conditions.

Abstract

This paper proposes an accurate algorithm to implement calibration-free wavelength modulation spectroscopy based on even-order harmonics. The proposed algorithm, analytically deduced from a much more accurate Voigt function model, enabling not only speedy measurement down to milliseconds, but also a general suitability for various degrees of line-shape broadening. The proposed method is validated by condition-controlled experiment, indicating calculation of gas temperature with the relative error less than 2.4% in the experiments.