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New grating concepts in the NIR and SWIR spectral band for high resolution earth-observation spectrometers

 
: Flügel-Paul, T.; Kalkowski, G.; Benkenstein, T.; Harzendorf, T.; Matthes, A.; Zeitner, U.D.

:

Navarro, R. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II : 26 June-1 July 2016, Edinburgh, United Kingdom
Bellingham, WA: SPIE, 2016 (Proceedings of SPIE 9912)
ISBN: 978-1-5106-0203-8
ISBN: 978-1-5106-0204-5
Paper 99122A, 7 pp.
Conference "Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation" <2, 2016, Edinburgh>
English
Conference Paper
Fraunhofer IOF ()

Abstract
We report about our latest achievements to realize the diffraction gratings during the development activities for a future Earth observation high resolution spectrometer studied by ESA. The gratings are manufactured by electron beam lithography on fused silica substrates. The optical performance is considerably increased by applying a dedicated high refractive index coating to the grating structure using atomic layer deposition (ALD). Thus, we were able to achieve diffraction efficiencies larger than 75% averaged over both linear polarizations states, i.e. TE and TM. At the same time, the polarization sensitivity is well below 10% in both cases. Finally, the diffraction gratings for the SWIR-1 spectral channel were bonded on a massive prism substrate in order to realize a GRISM element. This process was achieved by direct fused silica bonding performed under atmospheric pressure within special mechanical equipment designed and constructed particularly for this purpose.

: http://publica.fraunhofer.de/documents/N-445016.html