METHOD FOR DETERMINING DEFORMATIONS OF WAVEFRONT OF LIGHT BEAM CAUSED BY WAVINESS OF SURFACES OF OPTICAL SYSTEM Russian patent published in 2019 - IPC G01M11/02 

FIELD: optics.

SUBSTANCE: invention relates to the field of optics and can be used to determine the deformations of the wave front of a light beam that has passed through an optical system, caused by the waviness of the surfaces of the optical system. In the inventive method, an incoherent homocentric light beam with a wavelength λ is directed to the optical system. Position of the plane P_max is determined, in which the peak intensity of the light beam in the image of the cross-section of the light beam passing the optical system and focused in the image space has a maximum value of I_max among the experimentally recorded peak intensities in the images of the cross sections of the light beam. Diameter D of the light beam in the plane P is measured, perpendicular to the axis of the light beam and in contact with the last surface of the optical system, and the distance L_max to it from the plane P_max. Intensity distribution I(u,v) of the light beam in the coordinates (u,v) of the plane P_pr is registered, function ψ(u,v)=ln[I(u,v)/I(u,v)_cl] is determined and decomposed in a two-dimensional trigonometric Fourier series, the sequence number μ_max of the highest harmonic of the Fourier series is found, the square of the amplitude of which is not less than 0.02 from the square of the maximum amplitude value in the spectrum of harmonics. Intensity distribution I_reg(ξ,η) of light beam in the coordinates of the plane P_reg is registered, the position of the planes P_pr and P_reg is chosen away from the plane P_max according to the introduced ratios, taking into account the values of λ, D, μ_max, L_max. Wavefront deformations of the light beam w(x,y) caused by the waviness of the surfaces of the optical system are determined from the equation connecting w(x,y) in the coordinates (x,y) of the plane P with the intensity distribution of the light beam in the plane P_reg, the intensity distribution of the light beam I(x,y) is used, expressed in the coordinates of the plane P by replacing the variables in the distribution I_reg(ξ,η): Equation is solved by a variational method under free boundary conditions, approximating w(x,y) by a trigonometric polynomial.

EFFECT: determination of wavefront deformations of the light beam caused by the waviness of the surfaces of the optical system, with high accuracy while greatly simplifying the measurement process and reducing its labor intensity.

1 cl, 5 dwg