Pyroelectric camera tube systems

Claim 1

A pyroelectric camera tube system comprising a pyroelectric target for detecting by the pyroelectric effect thermal electromagnetic radiation incident thereon, means for repetitively scanning an ionic beam across a surface of said target, the product of the electrical resistance RT and the electrical capacitance CT of said target when scanned by said ionic beam being in the range from one-half of Tau F to 1,000 times Tau F, where Tau F is the average scanning period at which said means for scanning is capable of scanning said surface, the limits of said range being inclusive, a pick-up electrode in electrical contact with said target, said pickup electrode operating to produce an output signal corresponding to the quantity of pyroelectric charge developed at the part of said surface scanned by said electron beam, an electrical impedance having one end thereof electrically connected to said electrode, and a voltage source connected to the other end of said impedance, said voltage source providing a substantially steady electrical output voltage operative to leak, by conduction through said impedance and through said target to said scanned surface of said target, a quantity of charge of the opposite polarity to said ionic beam to form on said scanned surface a bias charge pedestal having a magnitude independent of said pyroelectric charge, said leaked charge acting as a quenching charge on said scanned surface capable of quenching in said average scanning period any excess charge left on said scanned surface from said ionic beam.