Infrared imaging system with simultaneously variable field of view and

Abstract

An infrared imaging system including a fixed magnification telescope, a two-axis variable angle scanner, a plurality of differently-sized infrared detectors positioned in the focal plane of the scanner, a selector to choose an output signal provided by one of the detectors, and a raster scan display. A single detector is associated with a particular desired field of view, with the size of the detector chosen to provide the desired resolution. To decrease the field of view encompassed by the imaging system, and thereby magnify the scene presented on the display, a smaller scan angle and a smaller detector are simultaneously selected. A gain and bandwidth normalization circuit is optionally used to normalize the electrical signals output by the various detectors. This arrangement allows reducing the field of view with a simultaneous change in the instantaneous field of view, so that resolution of a picture in the display accordingly increases. An object in focus in the display also remains in focus when th field of view is changed, so that the observer does not lose track of objects which must be followed closely. The system is small, mechanically simple, lightweight, and rugged, and can be packaged in a housing having approximately the same size and weight as a set of optical field binoculars.