A system in operation from 2003 to 2012 which allowed the light entering the twin Keck
Telescopes to be passed through a system of adaptive
optics to correct for turbulence in the Earth's atmosphere, and combined
through optical interferometry. The result of this technology was be to create an instrument with the resolving power of a single mirror 85 meters
in diameter. The Keck Interferometer was used for a range of science programs, including studies of active galactic nuclei and the formation of stars and planets.