light pen

noun, Computers.
1.
a hand-held light-sensitive device used for pointing at characters or objects on a CRT in order to make or modify drawings or to indicate functions to be performed.
Also called light pencil.
Origin
1955-60
Examples from the web for light pen
  • Input devices that may be used include a number pad, light pen, and touch sensitive display.
  • Other less commonly used pointer devices are the track ball, light pen, and graphics tablet.
British Dictionary definitions for light pen

light pen

noun
1.
(computing)
  1. a rodlike device which, when applied to the screen of a cathode-ray tube, can detect the time of passage of the illuminated spot across that point thus enabling a computer to determine the position on the screen being pointed at
  2. a penlike device, used to read bar codes, that emits light and determines the intensity of that light as reflected from a small area of an adjacent surface
light pen in Technology

hardware
An early pointing device which the user pointed at a raster-scanned display screen. A photocell in the pen detected the flying spot of the raster scan. The position of the spot at that instant, obtained from the scanning electronics, was made available to software as (x, y) co-ordinates.
(2003-12-02)