Instruments and Systems: Monitoring, Control, and Diagnostics Annotation << Back Investigation of Phase Fluctuations of the Output Signal of the Phase Measurement System E.E. MAIOROV, S.V. KOLESNICHENKO, A.A. KONSTANTINOVA, A.C. MASHEK, E.A PISAREVA, G.A. TSYGANKOVA The paper a study of the phase fluctuations of the output signal of the phase measurement system is presented. Obtaining high-precision and reliable information about controlled objects of various shapes has always been an important task of optical instrumentation, so the work is relevant. The paper investigates the random phase modulation of the output signal when extracting data from an interferogram, which makes it possible to assess the effect of the speckle field on the measurement error and the range of variation in the height of the relief of the controlled shape of the object. Fluctuations in the phase of the output signal at the aperture of the reproducing wavefront with different diameters are obtained. The values of the standard deviation of the output signal phase from the average value when the interferogram moves at different diameters are determined experimentally. Keywords: fluctuation, phase, interferogram, light wave front, object shape, speckle field. DOI: 10.25791/pribor.9.2021.1287 Pp. 01-06.