A fast and accurate gas concentration measurement method by fitting the main peak of the ab-sorption spectrum harmonic signal is proposed for the first time to significantly improve the speed and accuracy of gas concentration measurement by laser wavelength modulation spectroscopy (WMS ). In the proposed method,only the main peak of the absorption spectrum harmonic signal is scanned to obtain the peak value of the harmonic signal (WMS-2f/1f). This can greatly improve the scan speed due to the reduction of absorption spectrum scan range. Higher accuracy measurement can be achieved via fitting the main peak of the absorption spectrum harmonic signal (WMS-2f/1f)by a polynomial. The methods for choosing a suitable polynomial's degree and the influence of fitting data length on measurement result are discussed in this paper. The experi-mental results of carbon dioxide concentration measurement under different conditions validate the effectiveness of the proposed method.%为了提高激光波长调制光谱法(WMS)测量气体浓度的速度和准确度,首次提出了一种通过对吸收光谱谐波信号的主峰进行拟合的气体浓度测量方法.在该方法中,只扫描吸收光谱谐波信号的主峰部分来获得谐波信号(WMS-2f/1f)的峰值点.因为缩减了吸收光谱的扫描范围,所以扫描速度得到了提高.通过对吸收光谱谐波信号(WMS-2f/1f)的主峰部分进行多项式拟合,进一步提高了测量精度.详细讨论了多项式阶数的确认方法,以及拟合数据长度对测量结果的影响.通过测量不同情况下的二氧化碳浓度验证了该方法的有效性.
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