An air purge system for an optical sensor is disclosed. The air purge system includes a two sided lens having an optical sensor positioned on the first side and a fluid stream on the second side. The air purge system further includes, a plenum having an inlet, an array of parallel channels and an outlet, whereby the array of parallel channels, is disposed between the inlet and the outlet. The outlet is positioned on the second side of the housing and may be adapted to direct a fluid stream substantially parallel to the second side of the lens.