Abstract: A repetitive spectrally selective shutter apparatus which has a filter assembly in the space between a set of optics and the resultant focal plane is disclosed. The filter assembly consists of a narrowband filter mounted at an angle between the faces of two juxtaposed wedge-shaped faceplates. When rotated, this apparatus provides repetitive open periods in the narrow spectral bandpass as a function of the speed at which the filter assembly is rotated.

Abstract: Infra red (IR) vidicon camera tube performance is improved by alternately switching the sensing layer voltage to one of two values in synchronism with the frame rate of an IR TV camera. In operation the sensing layer is switched to a high voltage for two frames and then switched to the normal voltage for one frame readout. Camera tube response is in real time, thereby eliminating need for change in scanning beam rate or subsequent data processing of recorded video data.

Abstract: The processing by an infrared television system of field of view radiant emission data such as spatial, radiometric and spectral information is facilitated by apparatus and operating methods that utilize a rotatable narrow band interference filter. The filter intercepts radiant emission from a selected scene at a 0.degree. angle of incidence and at other selected angles of incidence up to 45.degree.. Distinguishing between laser and graybody targets is accomplished by continuously rocking the filter between 0.degree. and 45.degree. at the television vidicon scanning rate or some harmonic thereof.