Elimination of scale and luminance distortions in thermal imaging systems with a large field of view

When a thermal image is being recorded on photographic film that is continuously moving past the screen of a CRT operating in single-line scanning mode, the elimination of scale distortions through the use of a nonlinear electron beam sweep leads to a constant ratio of the tangents of the viewing and deflection angles in the CRT and consequently to considerable film density nonuniformity. The density falloff can be eliminated by increasing the luminance toward the end of the line for a constant signal at the CRT input.