Abstract: A wiper assembly for cleaning optical surfaces. The structure comprises a pneumatically activated wiper element including a wiping member connected to a spring member disposed within a cylinder. The wiper element is actuated by air pressure generated by a pumping element. The wiping member is connected to an end of a piston rod which passes longitudinally through the cylinder. When activated, the wiping element moves across an optical surface to be cleansed, and at a conclusion of its return stroke, has removed during its simple return stroke, frost, hydrocarbons, entrained particulate material and moisture from the optical surface.

Abstract: A cycling chilled mirror hygrometer is described wherein the mirror employed comprises a sapphire substrate having deposited thereon alternating layers of titanium dioxide and silicon dioxide. The surfaces resulting from the described technology yield a ten fold enhancement over the "theoretically pure" optical surface characteristics achieved with the prior art gold mirrors. Additionally, these devices have provided ideal surface characteristics for 350 degree optical triangulation, thereby permitting greater primary sensor sensitivity at low humidity levels (below -40 Cdp) and the elimination of long term "optical reflective gain" variations due to aging characteristics as compared with the conventional gold mirrors having impurities.