A rapid method for measuring the figure of a radio telescope reflector

Abstract

The well-known Fourier Transform relationship between the complex illumination function and the diffraction pattern of an aperture has been applied to measurements of the reception patterns of dishes of the 5-km telescope; the results have provided contour maps showing the distribution of reflector surface errors with an accuracy of ~ 0.1 mm. By repeating the measurements at different zenith angles the structural deflections due to gravity were investigated.