A wavelength calibration method for photoelastic-modulated Fourier transform spectrometers
ISSN: 0260-2288
Article publication date: 10 June 2022
Issue publication date: 30 June 2022
Abstract
Purpose
An interferogram is produced by modulating the difference between the extraordinary refractive index and the ordinary refractive index for photoelastic crystals in photoelastic-modulated Fourier transform spectrometers (PEM-FTs). Due to the influence of the refractive index dispersion characteristics on the maximum optical path difference of the interferogram, it is necessary to study wavelength calibration methods.
Design/methodology/approach
A wavelength calibration method for PEM-FTs was proposed based on the modulation principle of the photoelastic-modulated interferometer and the relationship between the maximum optical path difference and the refractive index difference. A 632.8 nm narrow-pulse laser was used as a reference source to measure the maximum optical path difference () of the interferogram, and the parameter was used to calculate the discrete frequency points in the frequency domain. To account for the influence of refractive index dispersion on the maximum optical path difference, the refractive index curve for the photoelastic crystal was used to adjust the discrete frequency coordinates.
Findings
The error in the reconstructed spectral frequency coordinates clearly decreased. The maximum relative error was 2.5%. A good solar absorption spectrum was obtained with a PEM-FT experimental platform and the wavelength calibration method.
Originality/value
The interferogram is produced by adjusting the difference between extraordinary refractive index and ordinary refractive index for the photoelastic crystal in the PEM-FTs. Given the wavelength dependence on the refractive indices, in view of the modulation principle of the photoelastic modulated interferometer, the relationship between the maximum optical path difference and the refractive index difference, the variation law of the refractive index of the photoelastic crystal and the process of spectral reconstruction is presented in this paper.
Keywords
Acknowledgements
Data availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.
This work was supported by the National Natural Science Foundation of China (NSFC) (Grant No. 61505180) and the Natural Science Foundation of Shanxi Province (Grant No. 201901D111163).
Citation
Zhang, M., Jing, N., Liu, Z., Li, C. and Zhang, N. (2022), "A wavelength calibration method for photoelastic-modulated Fourier transform spectrometers", Sensor Review, Vol. 42 No. 4, pp. 377-383. https://doi.org/10.1108/SR-08-2021-0253
Publisher
:Emerald Publishing Limited
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