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 m2. 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.
@article{arxiv.1307.4275,
title = {Open-structure composite mirrors for the Cherenkov Telescope Array},
author = {Michal Dyrda and Jerzy Michalowski and Jacek Niemiec and Marek Stodulski},
journal= {arXiv preprint arXiv:1307.4275},
year = {2013}
}
Comments
In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.2232