POMATA: preventing environmental aging factors on Cherenkov mirror coatings with protective oils

S. Iovenitti; S. Crestan; G. Leto; E. Gibertini; S. Basso; A. Bianco; G. Bonnoli; M. Civitani; G. Lessio; G. Pareschi; G. Sironi; G. Valsecchi; G. Vecchi

doi:10.1117/12.3019057

26 August 2024 POMATA: preventing environmental aging factors on Cherenkov mirror coatings with protective oils

S. Iovenitti, S. Crestan, G. Leto, E. Gibertini, S. Basso, A. Bianco, G. Bonnoli, M. Civitani, G. Lessio, G. Pareschi, G. Sironi, G. Valsecchi, G. Vecchi

Author Affiliations +

Proceedings Volume 13100, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI; 1310064 (2024) https://doi.org/10.1117/12.3019057
Event: SPIE Astronomical Telescopes + Instrumentation, 2024, Yokohama, Japan

Conference Poster

Abstract

POMATA (Protective Oils for Mirrors Aging on Telescopes Alfresco) is a project funded by the Italian National Institute for Astrophysics (INAF) aimed at identifying an adequate protective overcoating layer for mirrors used on Cherenkov telescopes. Unlike traditional observatories with domes, Air-Cherenkov instruments lack protective enclosures, exposing their mirrors to a range of detrimental elements, including atmospheric agents, thermal shocks, chemical reactions, and abrasive particles. Usually, on top of the mirrors’ reflecting layer a protective nanometric coating transparent in the UV band (e.g., SiO2) is deposited under vacuum. However, an additional over-coating is desirable to prevent micro-damages. Moreover, mitigating the accumulation of dirt on the mirror surface would be beneficial, as it may reduce the effective area and degrade the telescope’s performance. For this reason, we are currently working on the POMATA project, whose main goal is to conduct a comparative study of various overcoating layers that can be applied without depositions under high vacuum conditions. Our study is focused on silicone oils, a class of synthetic polymers composed of siloxane units. Silicone oils are well known for their unique properties, such as low surface tension, even spreadability, and resilience to extreme temperatures and environmental stressors. We evaluated four commercial silicone oils during a preliminary phase, and we are now testing their effectiveness in preventing aging as an additional layer for the Cherenkov mirrors developed for the project ASTRI. This contribution will cover the project’s development program and the results achieved after a preliminary characterization campaign.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

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S. Iovenitti, S. Crestan, G. Leto, E. Gibertini, S. Basso, A. Bianco, G. Bonnoli, M. Civitani, G. Lessio, G. Pareschi, G. Sironi, G. Valsecchi, and G. Vecchi "POMATA: preventing environmental aging factors on Cherenkov mirror coatings with protective oils", Proc. SPIE 13100, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI, 1310064 (26 August 2024); https://doi.org/10.1117/12.3019057

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