Conventional wavelength modulation spectroscopy(WMS)is vulnerable to the influence of low-frequency noise.Accuracy of the method highly depends on the performance of the costly lock-in amplifier.In this article,we rep...Conventional wavelength modulation spectroscopy(WMS)is vulnerable to the influence of low-frequency noise.Accuracy of the method highly depends on the performance of the costly lock-in amplifier.In this article,we report a new and effective method for reconstructing second-harmonic signals through WMS based on fast Fourier transform(FFT).This method is less disturbed by low-frequency noise because it does not use a low-frequency ramp wave.Formulation and detection procedures were presented.The discrete second-harmonic waveform can be obtained by continuously changing the DC signal and FFT analysis in this method.Second-harmonic waveforms acquired by the two means are generally consistent.The experimental study validates the obtained gas concentration from 5% to 30%,showing a good linear relationship by the proposed method.The maximum relative error on concentration extraction is 2.87%;as for conventional WMS,this value is 4.50%.The developed measurement method may have potential in computed tomography.展开更多
基金supported in part by the National Natural Science Foundation of China(Nos.61411130312 and 61308053)Guangdong Provincial Key Laboratory of Semiconductor Micro Display(No.2020B121202003)Foshan Science and Technology Bureau。
文摘Conventional wavelength modulation spectroscopy(WMS)is vulnerable to the influence of low-frequency noise.Accuracy of the method highly depends on the performance of the costly lock-in amplifier.In this article,we report a new and effective method for reconstructing second-harmonic signals through WMS based on fast Fourier transform(FFT).This method is less disturbed by low-frequency noise because it does not use a low-frequency ramp wave.Formulation and detection procedures were presented.The discrete second-harmonic waveform can be obtained by continuously changing the DC signal and FFT analysis in this method.Second-harmonic waveforms acquired by the two means are generally consistent.The experimental study validates the obtained gas concentration from 5% to 30%,showing a good linear relationship by the proposed method.The maximum relative error on concentration extraction is 2.87%;as for conventional WMS,this value is 4.50%.The developed measurement method may have potential in computed tomography.
