An electric eye is a photodetector used for detecting obstruction of a light beam. An example is the door safety system used on garage door openers that use a light transmitter and receiver at the bottom of the door to prevent closing if there is any obstruction in the way that breaks the light beam. The device does not provide an image; only presence of light is detectable. Visible light may be used, but infrared radiation conceals the operation of the device and typically is used in modern systems. Originally systems used lamps powered by direct current or the power line alternating current frequency, but modern photodetector systems use an infrared light-emitting diode modulated at a few kilohertz, which allows the detector to reject stray light and improves the range, sensitivity and security of the device.
Read more about Electric Eye: Examples
Famous quotes containing the words electric and/or eye:
“Flabby, bald, lobotomized,
he drifted in a sheepish calm,
where no agonizing reappraisal
jarred his concentration of the electric chair—
hanging like an oasis in his air
of lost connections. . . .”
—Robert Lowell (1917–1977)
“But the lightning which explodes and fashions planets, maker of planets and suns, is in him. On one side elemental order, sandstone and granite, rock-ledges, peat-bog, forest, sea and shore; and on the other part, thought, the spirit which composes and decomposes nature,—here they are, side by side, god and devil, mind and matter, king and conspirator, belt and spasm, riding peacefully together in the eye and brain of every man.”
—Ralph Waldo Emerson (1803–1882)