METHOD OF DETERMINING MEAN SQUARE DEVIATION OF OPTICAL SURFACE ROUGHNESS Russian patent published in 2024 - IPC G01B11/30 

FIELD: optical instrument making.

SUBSTANCE: invention relates to optical-electronic systems for controlling the quality of optical surfaces, and can be used to study roughness parameters of high-precision optical surfaces. Method provides for approximation of recorded indicatrix of scattered radiation ARS(Θ_d,Θ_n) by points, which are assigned based on the results of recording the indicatrix itself ARS(Θ_d,Θ_n), based on a given value of the minimum spatial frequency of the inhomogeneities ν_min, as well as based on the calculated values of PSD(ν) and the maximum frequency ν_max. Optical surface is illuminated with a narrow radiation beam at wavelength λ at angle of incidence Θ_n, indicatrix ARS(Θ_d,Θ_n) is recorded, scattered radiation spectral density function PSD(ν) is determined from the expression. Determining the effective value of the root-mean-square deviation of the roughness of the optical surface δ_eff² within the specified limits of the spatial frequency of the inhomogeneities from ν₁ to ν₂ by the expression. Value of the maximum frequency ν_max is additionally determined from the expression. Function ARS(Θ_d,Θ_n) is approximated in the range of scattering angles from Θ_dmin to 90° by expression. Function of spectral density PSD_apr(ν) is determined from the expression and the value of the root-mean-square deviation of the roughness of the optical surface is determined in the specified range from ν_min to ν_max from the expression.

EFFECT: wider frequency range of measuring the effective value of the root-mean-square deviation of the roughness of the optical surface in the region of high spatial frequencies of surface inhomogeneities, which in turn makes it possible to control surfaces with extremely small values.

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