electric eye

electric eye (plural electric eyes)

1. A sensor which measures the intensity of light, often used to start and stop electrical equipment (motorized doors, etc.).
   • 1928 February 10, “Span Atlantic by Electric Eye”, in Spokesman-Review, Spokane, USA, retrieved 14 November 2013, page 1:

     A man and woman sat before an electric eye in a London laboratory tonight and a group of people in a darkened room in this village outside New York watched them turn their heads move from side to side.

   • 1996 November 29, Richard Perez-Pena, “Rail Accident Stirs Debate About Sensors”, in New York Times, retrieved 14 November 2013:

     Another frequently cited possibility is a system of electric eyes reading beams of light that are aimed along tracks so that any displacement of the rails would disrupt the beam.

   • 2005 May 10, Gary Shapiro, “Botanical Garden Will Unveil Eight New Greenhouses”, in New York Sun, retrieved 14 November 2013:

     The doors have electric eyes: "If you're carrying large specimens or carts full of plants, the electric eye beam is broken and the door opens up."

• photocell, photoelectric cell

• “electric eye”, in OneLook Dictionary Search.