The response of photographic materials to electrons with particular reference to electron micrography

Abstract

SUMMARY The response of photographic emulsion layers to electron beam exposures is reviewed in simple terms, particularly for those energies used in conventional electron micrography. Emphasis is placed on the way many features of response are determined by the fact that a single electron serves to render several grains developable. In particular it is shown that the contrast is independent of emulsion/developer combination, the granularity is uniquely related to the speed, and the signal/noise ratio increases with exposure irrespective of the conditions leading to exposure increase. Demonstrations of these aspects are presented. Factors governing image spread are also outlined. The dependence of the minimum magnification for observation of details of a given size on this property is discussed.