A beam director may take the form of a siderostat, or a Coude' telescope of Alt-Az, Alt-Alt, or equatorial configuration.
DFM Engineering has built a Alt-Alt (altitude over altitude) beam director/Tracker (BD/T) with a 0.8 meter aperture and a Coude' optical system. DFM has also built Alt-Az (altitude over azimuth) beam director configurations. This system is located at the US Air Force Maui Optical Station and has been used for many experiments, including the Relay Mirror Experiment (RME).
Coeleostats: A coeleostat is typically a siderostat, but the word is poorly defined. The name may also be used to describe a beam director.