Asymmetric purge air system for cleaning a lens

Abstract From the Canadian patent

A purging air flow system for passing air over a lens to keep it clean and free from particulate contaminants and also for providing a positive flow of air away from the lens has baffles which cause a flow across, the lens that is not symmetrical to avoid a dead air or stagnation zone in the center of the lens . The air supply used for such purging is controlled adequately so the flow changes direction and particles are removed from the main flow of purge air by inertial separation prior to the time the air contacts the lens . Such air entrained particles might otherwise deposit on the lens . A flow control orifice also may provide a secondary flow to carry the particles separated from the …