phototube[fōt′ō to̵̅o̅b′, -tyo̵̅o̅b′]
phototube definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a vacuum tube designed to convert light energy into electrical energy by means of a photoemissive cathode
Origin: photo(electric) plush tube
phototube definition by American Heritage Dictionary
An electron tube with a photosensitive cathode.