0 a pen-shaped device used for reading bar codes
1 a pen-shaped object that uses beams of light to read bar codes (= small rectangular patterns of printed lines that store data) or that you use to touch a computer screen in order to choose information:
The endocardial contour of an end-systolic and an end-diastolic frame was digitized with a light pen on an electronic drawing board.
The process is carried out by means of a light pen which reads a bar code which transmits information on to a magnetic tape.
A light pen detects a change of brightness of nearby screen pixels when scanned by cathode ray tube electron beam and communicates the timing of this event to the computer.
In that system, the user could draw using a light pen on a screen and manipulate graphic primitives such as arcs and lines.
Terminals provided data entry capability into mainframes as well as light pen pointing and selection before the mouse was in use.
The light pen itself had a small photoelectric cell in its tip.
The computer had a wide selection of ports, including one for a light pen.
The other system, still in use in 2004, is based on a magnetic card and a voting machine with a light pen.
