Patent US 4,958,077

The present invention is concerned with displaying moving objects (targets) wherein two time-shifted object signatures are imaged on a detector. Target scanning is with a prismatic rotating wheel, the periphery of which has a plurality of adjacent, recessed, and oppositely reflecting triplet mirror surfaces which alternately reflect the two signatures onto the detector. The position coordinates of the objects are defined by taking the difference of the detector output signals of the two object signatures. The display is characterized in that the first signature scan is delayed by an intermediate storage so that it shall be simultaneously available with the second signature scan. After taking the difference of the signals of these signature scans, the uncanceled individual signals remaining in the storage are defined as the coordinates of the moving objects and appear as electronic outputs.