The Physics of Solid-State Light Amplifiers

An essential component of present light amplifying screens is a layer of inorganic, luminescent material. The ability of this layer to derive energy from an electric field to which it is subjected and convert this energy into visible light (i.e., electroluminescence) is fundamental to, but not alone sufficient for the realization of solid-state light amplification. What must be included is some means whereby the luminescent response to the field can be strongly controlled by incident radiation. In one case this has been obtained through the discovery of a phosphor film with the necessary properties, and in another by the utilization of a photoconducting material in contact with an electro-luminescent layer. In the latter case the photoconductor is the radiation-sensitive element, which serves to modify the potential across the luminescent component. The main characteristics of these light amplifying screens will be described, with particular emphasis on the interpretation of the phenomenon observed with the single phosphor film. The behavior, as it is relevant to their possible use in radiation detection will be discussed.