An optical method for the correction of slant range distortion in high-altitude radar recordings is presented. The line image of the scan is converted into a circular disk by rotation about the zero slant range point and an appropriate line from this disk is selected. This method is strictly geometrical (not an approximation) and readily accomodates altitude changes.
The method employs a reflecting cone as an optical element. The laws of reflection and image formation for this element are formulated, including the light efficiency.
A simple method for testing the quality of the conical surface is also given.
LEO LEVI, "Accurate Method for Correction of Slant Range Distortion in High-Altitude Radars and a Contribution to the Optics of Reflecting Conical Surfaces," J. Opt. Soc. Am. 48, 680-680 (1958)