photocathode

/ˌfoʊtoʊˈkæθoʊd/
noun
  1. A negatively charged electrode that releases electrons when light shines on it, used in devices like night-vision goggles and some light sensors.
    • Engineers improved the photocathode's efficiency by coating it with a special material.
    • The photocathode in the camera tube converts light into an electrical signal.
    • Night-vision devices rely on a sensitive photocathode to amplify dim light.