Abstract：A fast and accurate gas concentration measurement method by scanning the main peak of the wavelength modulation spectroscopy (WMS) absorbance spectrum was proposed for the first time to significantly improve the speed and accuracy of WMS measurement. In the proposed method, we only scan the main peak of the WMS absorption spectrum to obtain the peak value of the WMS-2f/1f spectral signal. This can greatly improve the scanning frequency. Higher accuracy detection of the peak of the WMS-2f/1f signal is achieved via fitting the main peak part of the WMS-2f/1f signal by a polynomial. The methods for choosing a suitable polynomial’s degree and the fitting length are discussed in this paper. The experimental results of CO2 measurement validated the proposed method.
