Prototype photon counting system, c 1980s.
© Science Museum / Science & Society Picture Library
This prototype was developed by Profesor Alex Boksenberg (former Director of the Royal Greenwich Observatory) and was used on the 200-inch Hale Telescope at Mount Palomar. It was constructed by the Department of Physics and Astronomy at University College, London, and is an extremely sensitive camera that can virtually detect a single photon. A notable example of this type of detector is to be found in the faint object camera on the Hubble Space Telescope.