pho·to·e·lec·tric cell
noun/ˌfəʊtəʊɪˌlektrɪk ˈsel/
/ˌfəʊtəʊɪˌlektrɪk ˈsel/
(also photocell)
- an electric device that uses a stream of light. When the stream is broken it shows that somebody/something is present, and can be used to control alarms, machines, etc.
光电池；光电感应器；光电管