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PhotocathodeIn a photomultiplier or Phototube, a photocathode is a negatively charged electrode coated with a photosensitive compound. When this is struck by light, electrons are emitted due to the photoelectric effect. Additional recommended knowledgeAlthough a plain metallic cathode will exhibit photoelectric properties, the specialized coating greatly increases the effect. A photocathode usually consists of alkali metals with very low work functions. The coating releases electrons much more readily than the underlying metal, allowing it to detect the low-energy photons in infrared radiation. The lens transmits the radiation from the object being viewed to a layer of coated glass. The photons strike the metal surface and transfer electrons to its rear side. The freed electrons are then collected to produce the final image. Photocathode materials
by DEBASISH ROUT References
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Photocathode". A list of authors is available in Wikipedia. |