Optical performance of narrow-band transmittance filters under low- and high-energy proton irradiation

摘要

The behaviour of interference optical filters for space applications has been investigated under low- and high-energy proton irradiation. Low-energy protons are expected to be necessary to prove the effects on the coating, whereas the high-energy proton tests shall verify mainly the substrate susceptibility to induced damage. The expected interaction of protons with coating and substrate was simulated by software, to identify the most appropriate conditions for the irradiation experiments. Two different accelerator facilities were used for low- and high- energy protons: 60 keV protons with an integrated fluence of 10~(12) p~+/cm~2 and 30 MeV protons with an integrated fluence of 10~8 p~+/cm~2. The spectral transmittance of the filters was measured before and after irradiation and, according to simulations, no significant effects were detected in the visible-near infrared spectrum, while some variations appeared at short wavelengths with low-energy irradiation.