Electronic Scanning System for Infrared Imaging

A new all electronic infrared imaging system has been designed and constructed. The infrared image of a given field of view is focussed onto a scanning tube which dissects the image; after passing through the scanning tube, the radiation is then refocussed onto a separate infrared detector. The tube face is a semiconducting window. An electron beam, striking the window, generates free carriers and reduces the transmission of the window locally. As the electron beam is swept across the scanning tube face, the moving opaque spot produces a video signal at the detector. Both the conditions for the operation of the device and the over-all sensitivity have been analyzed. It is found that the sensitivity and information rate of the system are limited only by the sensitivity and time constant of the detector employed.