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Proceedings Paper

Design and first light of the Sentinel-5 UV1 spectrometer optics
Author(s): Rik Jansen; James P. R. Day; Rob Vink; Jan de Vreugd; Erik R. J. van Beekum; Ludger W. van der Laan; Adriaan C. A. van 't Hof; Wim L. M. Gielesen; J. Koehler
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Paper Abstract

Sentinel-5 is an Earth atmospheric monitoring mission developed within the Copernicus program. The mission objective is to monitor the composition of the Earth’s atmosphere on a daily basis. TNO is developing the UV1 spectrometer subsystem as well as the two telescope subsystems. In this paper, the design of the UV1 spectrometer is described and its major design and verification challenges are discussed.

The UV1 optical design is based on a classical Offner-type spectrometer which has been adapted to employ freeform optics and an aspheric off-axis grating. It generates a magnification of 0.4. A structural, monolithic housing has been designed that is optimized for stability, accessibility and integration of optical components. To realize a thermo-mechanically stable construction, both housing and mirror bodies are built from aluminum. Four out of five mirrors have a dedicated black coating for absorbing out-of-band light. For further stray light suppression, a graded short-pass filter is employed on the last optical element just in front of the detector.

Performance verification of a standalone spectrometer without telescope, entrance slit, limiting aperture stop and flight detector is a major challenge. For this verification TNO developed dedicated ground support equipment that will be used under both ambient and vacuum conditions; a dedicated optical stimulus that mimics the illumination from the telescope in terms of pointing and NA, a Slit Assembly that mimics the homogenizer entrance slit and a Test Detector to determine the image plane and to measure the optical performance with high accuracy.

At the time of writing this article, the first (proto-flight) model has been aligned and performance verification is about to start.

Paper Details

Date Published: 10 October 2019
PDF: 13 pages
Proc. SPIE 11151, Sensors, Systems, and Next-Generation Satellites XXIII, 111510Q (10 October 2019); doi: 10.1117/12.2532400
Show Author Affiliations
Rik Jansen, TNO (Netherlands)
James P. R. Day, TNO (Netherlands)
Rob Vink, TNO (Netherlands)
Jan de Vreugd, TNO (Netherlands)
Erik R. J. van Beekum, TNO (Netherlands)
Ludger W. van der Laan, TNO (Netherlands)
Adriaan C. A. van 't Hof, TNO (Netherlands)
Wim L. M. Gielesen, TNO (Netherlands)
J. Koehler, Airbus Defence and Space (Germany)

Published in SPIE Proceedings Vol. 11151:
Sensors, Systems, and Next-Generation Satellites XXIII
Steven P. Neeck; Philippe Martimort; Toshiyoshi Kimura, Editor(s)

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