Interferometry of absolute distance at harmonic modulation of semiconductor laser with external optical feedback
Dobdin S.Yu., Dzhafarov A.V., Inkin M.G., Skripal A.V., Saratov National Research State University named after N.G. Chernyshevsky, Saratov, Russia
Abstract
The results of modeling a self-mixing laser as a laser probe for micro-displacement control are presented. A method for selecting the spectral harmonics of the low-frequency spectrum of self-mixing laser for measuring the absolute distance with harmonic modulation of the laser diode wavelength is proposed. The calculation was performed using the PyCharm IDE and Numpy and Matplotlib software modules. The accuracy of measurements was evaluated taking into account the accuracy of measuring the power of the self-mixing signal and the amplitudes of spectral harmonics on the installation at various deviations of the laser wavelength. It is shown that due to the ambiguity of the Bessel functions included in the algorithm, for reliable distance determination, it is necessary to restrict the selection of spectral components to the area of unambiguity, which is located at the end of the significant range of the spectrum. The error of determining the absolute distance from the deviation of the laser wavelength is investigated. It is found that when the distance to the reflector decreases, it is necessary to increase the value of the deviation of the laser radiation wavelength so that the set of measured harmonics is in the high frequency region. It is shown that in the deviation range from 0.1 nm to 1 nm at a distance of 50 to 100 mm, the measurement accuracy can reach units of microns. The promising application of self-mixing laser is determined by the task of developing laser probes for monitoring micro-displacements in a narrow range of measured distances.
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Speaker
Alexey Dzhafarov
SSU
Russia
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