Т.А. Lezhnina, V.V. Rozhentsov

Critical flicker fusion frequency (CFFF), at which there is a subjective sensation of light flicker fusion and the visual system perceives the source of radiant continuously, is due to the inertia of the visual system. The model of CFFF as a lowpass filter (LPF) with a variable cutoff frequency that displays low-frequency random process is considered. Visual system perceives the light flicker at frequencies lower then CFFF and does not accept them, that is feeling the flickering light source is illuminated continuously at frequencies higher then CFFF. The value of CFFF interpreted as the cutoff frequency of LPF. To represent the experimental data obtained in a series of CFFF measurements, used piecewise-linear approximation of the filter amplitude-frequency characteristic (AFC). If the present CFFF value obtained by probationer through a series of measurements in the form of variational series, the terms of this model the smallest value FCFFFmin is interpreted as an upper cutoff frequency of LPF passband, below which light flicker are seen and the greatest value of FCFFFmax - as an upper cutoff frequency of LPF stopband, above which flicker merge. In the transition band between the cutoff frequency is the actual CFFF value. When approximating the AFC LPF Butterworth and Chebyshev polynomials, which have the most simple analytical expressions, the slope of the frequency characteristics determined by the filter order n, which is a quantitative assessment of the variation range of CFFF values for a particular probationer at a given time. According to the results of experimental studies the approximation accuracy of the linear plot of the filter AFC recession according to the criterion of least sum of squared deviations by using Chebyshev polynomials is higher compared to the Butterworth polynomial.