Enhancing real-time perception of quantum limited images from a doubly intensified SIT camera system

Abstract

By a combination of three separate enhancing procedures, the visual perception of quantum limited images from a sensitive low-light camera system has been improved with significantly less image lag than is obtained using digital averaging alone. The camera system employed consists of a dual microchannel plate image intensifier optically coupled to a silicon-intensified target vidicon. With this camera system a major portion of the background noise can be removed by passing the video signal through an adjustable video slice circuit which excludes low level signals and represents signals above the slice threshold with a uniform white value. In addition, real image information can be integrated on the vidicon target by reducing the vidicon beam current to induce image lag of up to 2 s duration. Finally, the remaining noise which is characterized by lack of lag can be easily removed by moderate digital averaging. The enhancement obtained by these techniques is continuously variable allowing the user to select an enhancement level appropriate for the image under study.