Radiation vulnerability of standard and radiation-hardened optical glasses at MGy dose: Towards the design of tolerant optical systems

International audienceFacing the need of cameras able to withstand high levels (MGy) of ionizing radiation and the limited set of radiation-hardened optical glasses available to manufacture the lenses of their optical systems (OS), we performed an evaluation of standard and radiation hardened glasses. One of our objectives was to understand if selecting only radiation hardened glasses is always the best choice to reduce OS radio-darkening that is the main radiation-induced macroscopic degradation. For this, we performed X-ray in situ measurements of the radiation-induced attenuation (RIA) up to 100 kGy(SiO2) for several Ce-doped glasses from SCHOTT. Their responses are compared to their Ce-free counterparts. Due to the strong intrinsic attenuation of radiation hardened glasses caused by the Ce-codoping at shorter wavelengths, we found nearly no advantage to use radiation-hardened glasses at doses below 1 kGy(SiO2). We also performed post-irradiation RIA measurements on 31 standard glasses irradiated up to 1 MGy (γ-rays). The outcome is that several standard glasses especially the ones with a low Abbe number and a high refractive index are sufficiently radiation tolerant in terms of RIA and can serve as promising alternative to rad-hard ones. The use of these glasses less affect the color rendering of OS and strongly reduce their costs