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arXiv · 1307.4275

Open-structure composite mirrors for the Cherenkov Telescope Array

Michal Dyrda·Jerzy Michalowski·Jacek Niemiec·Marek Stodulski
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Abstract

The Cherenkov Telescope Array (CTA) Observatory for high-energy gamma-ray astronomy will comprise several tens of imaging atmospheric Cherenkov telescopes (IACTs) of different size with a total reflective area of about 10,000 m$^2$. Here we present a new technology for the production of IACT mirrors that has been developed in the Institute of Nuclear Physics PAS in Krakow, Poland. An open-structure composite mirror consists of a rigid flat sandwich support structure and cast-in-mould spherical epoxy resin layer. To this layer a thin glass sheet complete with optical coating is cold-slumped to provide the spherical reflective layer of the mirror. The main components of the sandwich support structure are two flat float glass panels inter spaced with V-shape aluminum spacers of equal length. The sandwich support structure is open, thus enabling good cooling and ventilation of the mirror. A special arrangement of the aluminum spacers also prohibits water being trapped inside. The open-structure technology thus represents a novel cost-efficient approach that does not require the perfect sealing needed in closed-type mirrors. In addition, the technology enables the application of a dielectric coating. Full-size prototype mirrors designed for the medium-size CTA telescope will be presented together with the results of recent optical tests.

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Michal Dyrda, Jerzy Michalowski, Jacek Niemiec, Marek Stodulski. 2013-07-16. Open-structure composite mirrors for the Cherenkov Telescope Array. https://arxiv.org/abs/1307.4275

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