US Patent 7522834 Camera housing with self-cleaning view port

Apparatus for maintaining an unobstructed view for visual monitoring equipment comprises a housing to isolate the visual monitoring equipment from an external environment. An inlet to the housing is connectable to a source of gas under pressure for cooling and cleaning purposes. At least one outlet to the housing defines a view port to allow the visual monitoring equipment to acquire images external to the housing and to allow gas to exit the housing. The outlet constricts the flow of gas leaving the housing resulting in acceleration of the gas through the outlet to form an exit jet that maintains the outlet unobstructed by debris. The housing is simple in construction with few moving parts resulting in reliable and efficient operation.