Long-term change of transmission spectra of quartz glass contaminated with oleamide in vacuum.

The long-term changes in the transmission spectra of glass contaminated with oleamide were investigated under vacuum and atmospheric conditions. Oleamide as a contaminant material was deposited onto quartz glass substrates using a vacuum evaporation method. The transmission spectra of the glass contaminated with oleamide showed a decrease in transmittance in the ultraviolet region and transparency in the visible and near-infrared regions. During storage under vacuum, the transmittance in the visible and near-infrared regions decreased gradually over an extended period. This decrease was attributed to the formation of oleamide flakes several microns in size and the concomitant increase in light scattering. The formation of the flakes depended on the thickness of the oleamide, and flake formation was not observed in the case of a thin (0. 5 μ m) oleamide film. This flake formation is attributed to the evaporation of oleamide. The results suggest that the long-term degradation of optical data obtained from spacecraft in orbit should be checked on the ground. • Oleamide was deposited onto the glass in vacuum. • The transmittance of the contaminated glass decreased in the UV region. • The transmittance decreased gradually during storage under vacuum. • This behavior resulted from the formation of micron-sized flakes of oleamide. • This flake formation depended on the thickness of the oleamide. [ABSTRACT FROM AUTHOR]