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Proceedings Paper

The ASTRI SST-2M prototype for the Cherenkov Telescope Array: primary mirror characterization by deflectometry
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Paper Abstract

In 2014 the ASTRI Collaboration, led by the Italian National Institute for Astrophysics, has constructed an end-to-end prototype of a dual-mirror imaging air Cherenkov telescope, proposed for the small size class of telescopes for the Cherenkov Telescope Array. The prototype, named ASTRI SST-2M, has been installed at the observing station located at Serra La Nave (Italy). In this project the Brera Astronomical Observatory was responsible for the production and the testing of the primary mirror. The ASTRI SST-2M telescope’s primary mirror has an aperture of ~ 4 m, a polynomial design, and consists of 18 individual hexagonal facets. These characteristics require the production and testing of panels with a typical size of ~1 m vertex-to-vertex and with an aspheric component of up to several millimetres. The mirror segments were produced assembling a sandwich of thin glass foils bent at room temperature to reach the desired shape. For the characterization of the mirrors we developed an ad-hoc deflectometry facility that works as an inverse Ronchi test in combination with a ray-tracing code. In this contribution we report the results of the deflectometric measurements performed on the primary mirror segments of the ASTRI SST-2M dual mirror telescope. The expected point spread function and the contributions to the degradation of the image quality are studied.

Paper Details

Date Published: 21 September 2015
PDF: 8 pages
Proc. SPIE 9603, Optics for EUV, X-Ray, and Gamma-Ray Astronomy VII, 960304 (21 September 2015); doi: 10.1117/12.2188725
Show Author Affiliations
Giorgia Sironi, INAF - Osservatorio Astronomico di Brera (Italy)
Rodolfo Canestrari, INAF - Osservatorio Astronomico di Brera (Italy)

Published in SPIE Proceedings Vol. 9603:
Optics for EUV, X-Ray, and Gamma-Ray Astronomy VII
Stephen L. O'Dell; Giovanni Pareschi, Editor(s)

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