Reconstruction and fitting of second-harmonic signals by wavelength modulation spectroscopy method based on fast Fourier transform

Linquan Lai, Yue Chen, Kongtao Chen, Jiale Tang, Kaiwen Yin, Fuqiang Jia, Dun Qiao, Yuanlong Fan, Kang Li, Nigel Copner

Research output: Contribution to journalArticlepeer-review

19 Downloads (Pure)

Abstract

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.
Original languageEnglish
Article number093001
Number of pages5
JournalChinese Optics Letters
Volume20
Issue number9
DOIs
Publication statusPublished - 15 Jun 2022

Keywords

  • Fast Fourier Transform (FFT)
  • wavelength modulation spectroscopy
  • second-harmonic waveform

Fingerprint

Dive into the research topics of 'Reconstruction and fitting of second-harmonic signals by wavelength modulation spectroscopy method based on fast Fourier transform'. Together they form a unique fingerprint.

Cite this