Exposure study on UV-induced degradation of PTFE and ceramic optical diffusers

Abstract

We report on a study of the ultraviolet (UV)-induced degradation on optical grade polytetrafluoroethylene (PTFE) and ceramic diffuser samples. Long-term UV exposure may significantly alter the reflectance and lead to an error in the calibration of optical instruments. A large integrating sphere was used to irradiate the samples for 334.7 days at an irradiance level of 194.9 <i>W</i>/<i>m</i>². Samples were qualified and measured for reflectance factor, bidirectional reflectance distribution function, and fluorescence, before and after the exposure, and at 12-week intervals during the exposure. This study revealed significant differences between the aging behavior of ceramic and PTFE samples.