MEGARA anti-reflective coatings: theoretical  and observed throughput estimations

R. Ortiz; E. Carrasco; G. Páez; O. Pompa; E. Sánchez-Blanco; A. Gil de Paz; J. Gallego; J. Iglesias-Páramo

doi:10.1117/12.2313976

10 July 2018 MEGARA anti-reflective coatings: theoretical and observed throughput estimations

R. Ortiz, E. Carrasco, G. Páez, O. Pompa, E. Sánchez-Blanco, A. Gil de Paz, J. Gallego, J. Iglesias-Páramo

Proceedings Volume 10706, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III; 107065H (2018) https://doi.org/10.1117/12.2313976
Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States

Abstract

MEGARA is the new integral field unit (IFU) and multi-object (MOS) spectrograph successfully commissioned at Gran Telescopio Canarias, in August 2017. MEGARA provides spectral resolutions R (fwhm) ~ 6000, 12000 and 20000, via volume phase holographic gratings, at very high efficiency in both IFU and MOS modes. In the case of MEGARA main optics and pupil elements optics, the surfaces in contact with air have an anti-reflective (AR) coatings to minimize the Fresnel losses at the interface glass-air. In this work we present the designs and calculation of the total throughput of the optical system based in the transmission measurements of the AR coated witness samples. The results reflect the benefits of having implemented customized AR coatings for the mean angle of incidence on each surface as the measured throughput was better than the requirements. We analyze the effects of the pupil elements AR coatings for each spectral configuration.

Citation Download Citation

R. Ortiz, E. Carrasco, G. Páez, O. Pompa, E. Sánchez-Blanco, A. Gil de Paz, J. Gallego, and J. Iglesias-Páramo "MEGARA anti-reflective coatings: theoretical and observed throughput estimations", Proc. SPIE 10706, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III, 107065H (10 July 2018); https://doi.org/10.1117/12.2313976

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