Optical coatings for the Tropomi UV channel
van Buuren, R.A.
van der Valk, N.C.J.
van Brug, H.
Sodnik, Z. (editor)
Cugny, B. (editor)
Karafolas, N. (editor)
Earth observation measurements at wavelengths below 320nm are challenging due to the steep decrease of the earth irradiance towards shorter wavelengths. Stray light and ghosting of longer wave light can easily overwhelm the signals at short wavelengths. In the UV channel (270-320nm) of the TROPOMI instrument this challenge has been addressed using a number of coatings. Three black UV mirror coatings absorb light with a wavelength above 370nm. Together, these achieve more than four orders suppression of long wave out-of-band light. A lowpass transmission filter with a position dependent cut-off wavelength is deposited on the last lens surface, directly in front of the detector. At the position where short wavelength light passes the filter, longer wavelength in-band stray light and ghosts are blocked. A simulation predicts that this graded filter reduces ghosting by a factor 20 and scatter related stray light by factor 30.
2014 Mechanics, Materials and Structures
To reference this document use:
IM - Instrument Manufacturing
TS - Technical Sciences
High Tech Systems & Materials
International Conference on Space Optics, ICSO 2014, 7-10 October 2014, La Caleta, Tenerife, Canary Islands, Spain, 10563
Proceedings of SPIE - The International Society for Optical Engineering