A light fixture has a light-transparent cover at substantially grade level and a photocontrol device with a self-flushing outer surface for preventing accumulation of opaque material thereon. The light fixture is adapted to be positioned within a recess in the graded environment and includes a housing...http://www.google.com/patents/US4907139?utm_source=gb-gplus-sharePatent US4907139 - Photocontrol device for grade mounted light fixture
