Experiments for studying the suitability of carbon films for IR optics exposed to soft X-rays are described. IR reflectors coated with amorphous hard carbon films are optically characterized before and after thermal cycling (from 100 K to 300 K) and before and after thermal exposure to flash X-rays.
Mark D. Alvey, Mark D. Alvey,
"Soft x-ray, optical, and thermal properties of hard carbon films", Proc. SPIE 1330, Optical Surfaces Resistant to Severe Environments, (1 January 1991); doi: 10.1117/12.47516; https://doi.org/10.1117/12.47516