bolometer

bolometer (bol-LOM-i-ter) - n., a device for measuring faint electromagnetic radiation.


Works by measuring the change in electrical resistance caused by the changes in temperature in a black film. Invented in 1878 by American astronomer Samuel Langley. Name is coined from Greek root bolē, beam of light, from ballein, to throw + -meter. Here's a tiny one, used for measuring cosmic background microwave radiation.


Thanks, WikiMedia!

---L.