Focus tube

(Phys.) a vacuum tube for Rœntgen rays in which the cathode rays are focused upon the anticathode, for intensifying the effect.

See also: Focus

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
The monitors include Hitachi's PrecisionFocus technology, a 0.22mm horizontal dot pitch, a 0.16mm vertical dot pitch, an Advanced Elliptical Aperture, and a multi-step dynamic focus tube. The 3S series also includes a black matrix with an invar shadow mask, high contrast and an anti-static/anti-glare coating.