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Reflectivity loss due to dust deposition over primary mirrors is a key issue for ground-based astronomical observatories. Suspended atmospheric dust falls over the optical surface affecting its performance and optical quality. Several in-situ and off-site techniques have been developed for eliminating dust particulates from optical surfaces, but all of them present important drawbacks like being time-consuming, expensive, contaminant or even involving dangerous operations in off-site approaches. Alternatively, a method based on laser-matter interaction and SENER’s experience in ground telescopes, has been tested and developed. Laser cleaning is a discipline that covers a large range of applications, from semiconductor physical decontamination to the removal of oxides from metallic surfaces. The wide catalogue of laser systems currently available, allows us to investigate and design the best laser source for astronomical mirror maintenance. This has allowed us to develop a system that performs a proper cleaning for astronomical mirrors, which is currently bridging the gap between the laboratory demonstrator and the telescope application. In this communication we present the development of a laser cleaning system for the removal of dust particulates and contaminants attached to telescope mirror surfaces. Several configurations have been tested in the laboratory, under different conditions, and cleaning was performed over aluminized Zerodur® flat samples, that were naturally contaminated in Atacama’s desert and Canary Islands, aiming at the definition, manufacturing, and testing of a demonstrator prototype. Results show a large improvement of reflectivity after cleaning and contribute to the design of a custom efficient laser cleaning system adapted to different observatories.
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