Radiation detecting apparatus for detecting a brief radiation signal

Claim 1

Radiation detecting apparatus for detecting a brief radiation signal in the presence of background radiation, which includes a plurality of radiation-sensitive devices arranged in a two-coordinate array and each operable to cause the storage of an elecrtric charge proportional to the radiant energy incident upon it, a like plurality of storage elements each associated with a separate radiation-sensitive device, a transfer arrangement operable to transfer repetitively any stored charge to its associated storage element to store a radiation image frame, register means having a number of storage locations equal to the number of radiation-sensitive devices and arranged in a similar two-coordinate array, a shift arrangement operable to shift repetitively the radiation image frame stored in the storage elements into the register means in a series of parallel bit streams defined by one of said two coordinates and simultaneously to shift out of the register means for preceding radiation image frame, detector means operable to compare the contents of corresponding bit positions in each bit stream shifted into and out of the register means simultaneously, so as to detect changes in the radiation incident upon the array and to deliver an output signal when such a change is detected, a sampling circuit responsive to the output of the detector means associated with each separate bit stream and comprising a threshold circuit operable to deliver a signal only when the output of the detector means applied thereto exceeds a threshold level and a control circuit actuated by an output from the threshold circuit to cause instantaneous samples to be taken of the outputs of the detector means associated with each bit stream, and output means responsive to the sampled outputs to define the position in the radiation image frame of each bit position producing an output from the detector means.