Abstract: An analog computer method provides modulation transfer functions (MTF) expressions or graphs for arbitrary shaped detectors in an arbitrary scan direction. Fraunhofer diffraction calculations or measurements given for specific shaped apertures are used for calculating detector MTFs of similarly shaped detectors. In an analog measuring device, an aperture in an opaque screen may be made the shape of a detector whose MTF is to be calculated. The aperture is flooded with laser light which produces a Fraunhofer irradiance pattern at an observing screen which is parallel with the opaque screen, for measuring the irradiance in the Fraunhofer plane at the observing screen. A sensor, which has a detector small compared with the diffraction pattern, is moved along the chosen thermal imager scan direction, in the Fraunhofer plane.

Abstract: An automatic responsivity compensator for correcting video output signals om a CCD multiplexer in a cryogenic dewar in IR imaging systems wherein the CCD multiplexer must operate with fixed gain inputs from a plurality of linear detector channels. The automatic responsivity compensator is comprised of a signal reference that is normalized with what the output voltage should be when looking at a fixed temperature source in the field of view of the detectors and which further provides a voltage reference for automatic gain adjustment for each detector channel to normalize and equalize the responsivity of the detectors. The automatic responsivity compensator may be either a feedback system as a direct gain control means of a controllable gain amplifier or may be a feedback system operating on the output from a constant gain amplifier wherein either feedback system equalizes the responsivity of the detectors.