Analysis of the accuracy of the signal processing algorithm of the differential phase polarimeter

Abstract

The purpose of this work is to analyze the effect of the polarimeter signal processing algorithm on the results of measurements of the optical rotation angle of the polarization plane to improve the accuracy of measurements in differential polarimetry. Methods. The paper considers the methods of polarimetry used for the analysis of optically active substances, based on the methods of phase measurements used to calculate the optical rotation angle. The expediency of using the Fourier transform to calculate the phase difference of differential polarimeter signals is noted. To analyze the error of the algorithm, mathematical modeling of the measurement information processing for various signal parameters is applied. Results. The results of the study of the effect of the bit depth of the analog-to-digital converter, the number of samples over the period of the signal and the accumulation time on the accuracy of restoring the phase difference are presented. The influence of the ratio of signal amplitudes and the level of amplitude and phase noise caused by the imperfection of the measuring system has also been investigated. Conclusion. The obtained results make it possible to optimize the operating mode and improve the accuracy of the optical rotation angle measurements using a differential phase polarimeter based on the Fourier transform.

Keywords

• polarimetry
• optical rotation angle
• phase measurements
• harmonic signal analysis
• amplitude and phase noise
• fourier transform