Optical characterization of reflective coatings for astronomical telescope mirrors

  • With ground based optical telescopes astronomers observe celestial objects over a wide spectral range. As usually three or even more reflections at telescope mirrors are involved, good reflection properties of the mirror coatings are important. The aluminum evaporation technique has been - and is still - the standard solution for the reflective coatings of large astronomical mirrors. Such coatings have excellent reflectivity in the ultraviolet and in the visible, but perform poorly in the infrared. Silver is the metal having highest reflectivity for wavelengths longward of 400 nm, but isn´t the best choice for reflectivity in the ultraviolet and for blue light. To avoid degradation by oxidation, durable silver coatings need to be protected by transmitting overcoating layers. In the presented study, different metallic coatings – including unusual ones like sputtered iridium - are characterized to identify a coating that is most suitable for the spectral range from ultraviolet to infrared. Experimental results are compared to simulations based on the complex refractive indices of these materials. Thereby dependence of incidence angle and polarization is also considered.
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Author:Thorsten DöhringORCiD, Claudius Rödling, Kevin Kimmel, Sebastian Zeising, Johannes Stadtmüller, Manfred StollenwerkORCiD, Shruti Verma, Paul Rees
URL:https://dgao.de/jahrestagung/
Parent Title (English):DGaO Jahrestagung
Document Type:Other
Language:English
Year of Completion:2021
Date of first Publication:2021/09/21
Creating Corporation:TH Aschaffenburg
Contributing Corporation:Wrexham Glyndwr University
Release Date:2021/09/28
Tag:astronomy; coating; iridium; mirror; telescope
GND Keyword:Spiegelteleskop
Volume:2021
Page Number:1
First Page:1
Last Page:1
Urheberrecht:1
research focus :Materials / Innovative Material Processing
Materials / Material Testing & Sensor Technology
Licence (German):Keine Lizenz - es gilt das deutsche Urheberrecht
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