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Proceedings Paper

Brief history of photoemissive materials
Author(s): Alfred H. Sommer
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Paper Abstract

During the four decades from 1930 to 1970, seven photocathodes having useful sensitivity to visible light were developed. The first six have two features in common: First, they were all based on lucky observations, rather than on scientific principles. Second, despite a great deal of systematic research it is still not understood why these particular combinations of chemical elements have the observed properties. By contrast, a seventh type of photocathode, the so- called negative-electron-affinity (NEA) cathode materials were based on the principles of solid-state physics. The NEA cathodes have two advantages over the earlier materials in that they have higher photoelastic sensitivity and are better understood theoretically. However, they have the practical disadvantage that they involve single-crystal growth, whereas the earlier cathodes can all be produced by simple evaporation processes. As a result, they are used only in special applications.

Paper Details

Date Published: 15 October 1993
PDF: 16 pages
Proc. SPIE 2022, Photodetectors and Power Meters, (15 October 1993); doi: 10.1117/12.158564
Show Author Affiliations
Alfred H. Sommer, Consultant (United States)

Published in SPIE Proceedings Vol. 2022:
Photodetectors and Power Meters
Kenneth J. Kaufmann, Editor(s)

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