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Proceedings Paper

Spectralon diffuser calibration for MERIS
Author(s): Carina Olij; Jos Groote Schaarsberg; Henri G.C. Werij; Erik Zoutman; Gilles Baudin; Beatrice Chommeloux; Jean-Loup Bezy; Georges Gourmelon
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Paper Abstract

One of the key payload instruments of ESA's ENVISAT polar platform is the medium resolution imaging spectrometer (MERIS), aiming at improved knowledge of our planet in the fields of bio-optical oceanography, and atmospheric and land surface processes. MERIS, which is built under responsibility of Aerospatiale, will monitor the solar irradiation scattered by the Earth by employing five cameras which simultaneously record data in 15 visible and near-infrared programmable spectral bands with very low degree of polarization sensitivity. The combined field-of-view of the five cameras spans a range of 68.5 degrees. Crucial for obtaining the desired high accuracy during a four-years lifetime, is the on- board calibration unit. This calibration unit contains a set of Spectralon diffusers, which were manufactured having in mind excellent in-flight stability as well as spectral and spatial uniformity. Preflight calibration of the Spectralon diffusers was carried out at TNO-TPD. This calibration includes the measurement of the bidirectional reflectance distribution function (BRDF) for applicable angles and wavelengths, i.e., while varying angle of incidence, angle of observation, observation area on the elongated diffusers, wavelength and polarization. The diffuser calibration was performed in a class 100 cleanroom. For these measurements the TPD calibration facility, which is described in detail, has been adapted, so that it now has five geometrical degrees of freedom. Detectors have been optimized to minimize stray light. Due to extensive commissioning of the calibration setup the absolute error (1 sigma) of these measurements amounts to less than 0.5%; relative errors are in the 0.3 - 0.4% range.

Paper Details

Date Published: 31 December 1997
PDF: 12 pages
Proc. SPIE 3221, Sensors, Systems, and Next-Generation Satellites, (31 December 1997); doi: 10.1117/12.298122
Show Author Affiliations
Carina Olij, TNO Institute of Applied Physics (Netherlands)
Jos Groote Schaarsberg, TNO Institute of Applied Physics (Netherlands)
Henri G.C. Werij, TNO Institute of Applied Physics (Netherlands)
Erik Zoutman, TNO Institute of Applied Physics (Netherlands)
Gilles Baudin, Aerospatiale (France)
Beatrice Chommeloux, Aerospatiale (France)
Jean-Loup Bezy, European Space Agency/ESTEC (Netherlands)
Georges Gourmelon, European Space Agency/ESTEC (Netherlands)

Published in SPIE Proceedings Vol. 3221:
Sensors, Systems, and Next-Generation Satellites
Hiroyuki Fujisada, Editor(s)

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