Abstract: A bright source protection circuit for an image intensifier tube modulates the voltage supplied to the tube's photocathode in response to current drawn by the photocathode such that the photocathode is pulsed on and off until the desired photocathode current is achieved.

Abstract: A device for shielding an image intensifier from electromagnetic interference which includes a hollow conductive mantle surrounding the image intensifier and over the end except for light input and output windows. It is adapted to be electrically connected to a ground reference potential for diverting electromagnetic interference to the ground reference potential, and in this capacity, functions as a Faraday cage. The mantle contains a conductive plate, preferably in the form of a sleeve, affixed within it. The conductive plate is insulated from the mantle by a layer of dielectric substance. The conductive plate is adapted to be electrically connected with an input lead for powering the image intensifier; the conductive member, the interposed dielectric substance and the mantle comprising a bypass capacitor for the input power lead.

Abstract: An image intensifier tube having an electromagnetic interference protection arrangement. The protection is accomplished by shielding the tube and filtering the power supply. Shielding is performed by means of a conductive metallic coating which surrounds the image intensifier tube housing. Filtering is accomplished by using capacitors to short the interference to ground.