an electron tube with a photosensitive cathode, used like a photocell.
Origin of phototube
Also called photoelectric tube.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a type of photocell in which radiation falling on a photocathode causes electrons to flow to an anode and thus produce an electric current
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012