Mirror coating and cleaning methodology to maintain the optical performance of the GTC telescope

M. Abril-Abril; A. Nuñez-Castaín; L. A. Rodríguez-García; A. Cabrera-Lavers

doi:10.1117/12.2232310

27 July 2016 Mirror coating and cleaning methodology to maintain the optical performance of the GTC telescope

M. Abril-Abril, A. Nuñez-Castaín, L. A. Rodríguez-García, A. Cabrera-Lavers

Proceedings Volume 9906, Ground-based and Airborne Telescopes VI; 99063U (2016) https://doi.org/10.1117/12.2232310
Event: SPIE Astronomical Telescopes + Instrumentation, 2016, Edinburgh, United Kingdom

Abstract

This paper describes the strategy to optimize GTC telescope’s optical performance in terms of reflectivity and scattering by means of a suitable combination of mirror coating, CO² and in-situ cleaning. According to our experience, a monthly CO² cleaning was established, except during sporadic dust episodes, when a shorter weekly period is much more appropriate. Trends of the main optical parameters were recorded and analyzed to identify possible causes for the variation of the mirrors performance. As the total reflectivity stems from the combination of three optical surfaces, we set thresholds for the individual components and used these to select the mirrors that have to be replaced and cleaned. We also compared historical data about total reflectivity with optical OSIRIS zeropoints evolution and established a nonlinear relation, that is applicable in the periods where direct measurements on the mirror surface are not feasible. In this line, we are working on an innovative method to estimate the reflectivity for a segmented mirror based on the zeropoints measurement for the individual segments obtained by un-stacking the primary mirror under a controlled pattern.

Citation Download Citation

M. Abril-Abril, A. Nuñez-Castaín, L. A. Rodríguez-García, and A. Cabrera-Lavers "Mirror coating and cleaning methodology to maintain the optical performance of the GTC telescope", Proc. SPIE 9906, Ground-based and Airborne Telescopes VI, 99063U (27 July 2016); https://doi.org/10.1117/12.2232310

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available