Zhurnal Radioelektroniki - Journal of Radio Electronics. eISSN 1684-1719. 2021. №11
ContentsFull text in Russian (pdf)
DOI: https://doi.org/10.30898/1684-1719.2021.11.6
UDC: 534.63, 535.33
Using modulation acousto-optic spectrometry to locate spectral features in over-lapping spectra
S. V. Boritko, S. I. Ivanov, A. V. Karandin
Scientific and Technological Centre of Unique Instrumentation of the Russian Academy of Sciences, 117342, Moscow, Butlerova str. 15
The paper was received 23 November 2021
Abstract. The spectrometer is not able to accurately determine the spectral position of the smaller maximum if it is located against the background of a powerful broad peak. The solution of the problem is known it is enough to differentiate the existing dependence, and the position of the smaller peak is determined with sufficient accuracy. Based on a quasi-collinear acousto-optic (AO) cell, a prototype spectrometer was created, which makes it possible to record both the spectrum of the optical signal and its derivative in real time. In the course of the work, a more detailed research of the work of the created model was carried out: the value of the phase shift was changed programmatically from zero to 360°, and the spatial modulation period - from zero to the length of the AO cell L. A neon lamp and all the data presented were used as a radiation source, were obtained for the same emission line. The maximum signal for the derivative corresponds to the phase values of 90° and 270°. In another series of experiments, the work of the model was investigated with a change in the modulation period (the phase shift is fixed, ψ=π/2). The maximum signal for the derivative corresponds to the values of the modulation period duration equal to L/2, half the length of the acousto-optic cell. The graphs of the results of "physical" and "mathematical" differentiation do not coincide. We assume that the differences are related to the shape of the instrumental function of the acousto-optical spectrometer. However, at the tops of the spectral peaks, in the regions of intersection of derivatives with a zero line, the results coincide, which makes it possible to use acousto-optic differentiation to reveal the "fine structure" of optical spectra, and in real time. Thus, as a result of the work carried out: a method was proposed for the precise determination of the position of spectral maxima in complex overlapping spectra in real time; an instrumental implementation of the proposed method was created, and it was shown that for the visible range (532 nm) the accuracy of determining the spectral position of the maxima is 0.2 nm.
Key words: spectrometer, spectral position, acousto-optic cell, neon lamp, acousto-optic differentiation, fine structure, overlapping spectra.
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For citation:
Boritko S.V., Ivanov S.I., Karandin A.V. Using modulation acousto-optic spectrometry to locate spectral features in overlapping spectra. Zhurnal Radioelektroniki [Journal of Radio Electronics]. 2021. №11. https://doi.org/10.30898/1684-1719.2021.11.6 (In Russian)