A multi-function dental operating light source comprises a series of optical filters and flat reflectors mounted upon a turntable at spaced locations around the periphery, the turntable being rotatable about a fixed axis relative to a stationary tungsten halogen lamp having a parabolic reflector and...http://www.google.ca/patents/US4516195?utm_source=gb-gplus-sharePatent US4516195 - Multi-function dental operating light source
