An apparatus for mitigating contamination of an optical device comprises an open-topped, closed-sided, and closed-bottomed housing cup partially defining a protected volume to enclose the optical device. A housing cap encloses a top of the housing cup and partially defines the protected volume. The housing cap includes a top collar having an open central aperture. The top collar includes at least one drain channel extending longitudinally downward into a top collar top surface and extending across the top collar top surface laterally outward from the central aperture. A top cover laterally spans the central aperture of the top collar. An interface structure circumscribes the top cover to suspend the top cover downwardly into the housing cup from the top collar. The interface structure prevents direct contact between the top cover and the top collar.