Stray Light Calibration and Correction of EnMAP's Imaging Spectrometers

We report on the on-ground stray light calibration of the hyperspectral Environmental Mapping and Analysis Program (EnMAP) satellite mission, which was successfully launched into space on April 1, 2022. EnMAP's optical payload consists of a visible and near-infrared (VNIR) (420-1000 nm) and a s...

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Bibliographic Details
Published in:IEEE transactions on geoscience and remote sensing Vol. 63; pp. 1 - 16
Main Authors: Baumgartner, Andreas, Henning Kohler, Claas, Baur, Simon, Wachter, Richard, Polz, Leonhard, Serdyuchenko, Anna
Format: Journal Article
Language:English
Published: New York IEEE 2025
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:
Band-pass filters
Calibration
Collimators
Computing time
Detectors
Dynamic range
Environmental Mapping and Analysis Program (EnMAP)
hyperspectral
Imaging
imaging spectrometer
Imaging spectrometers
Instruments
Light
Light sources
Optical imaging
Optical variables measurement
Point spread functions
Response functions
Satellites
Spectrometers
Stray light
Wavelength
Wavelength measurement
ISSN:0196-2892, 1558-0644
Online Access:Get full text
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Summary:We report on the on-ground stray light calibration of the hyperspectral Environmental Mapping and Analysis Program (EnMAP) satellite mission, which was successfully launched into space on April 1, 2022. EnMAP's optical payload consists of a visible and near-infrared (VNIR) (420-1000 nm) and a short wavelength infrared (SWIR) (900-2450 nm) imaging spectrometer. Using a custom-built light source and a collimator, we determined the diffuse stray light by measuring the point spread functions (PSFs) at 12 spatial and 15 (11 VNIR, 4 SWIR) spectral positions with a dynamic range between eight and nine orders of magnitude. Additionally, we measured the out-of-field stray light in along-track direction over an angular range of ±0.2°, resulting in an along-track response function (AltRF) for each spectrometer unit with a dynamic range of <inline-formula> <tex-math notation="LaTeX">\sim 10^{7} </tex-math></inline-formula>. To reduce memory usage and computational time, we use a binned stray light extraction matrix to correct the diffuse stray light. The along-track out-of-field stray light of individual frames is corrected by subtracting preceding and following frames that are weighted with the AltRF. Finally, we show with simulations the impact of both types of stray light on a test scene and evaluate the performance of the presented correction methods in the same manner.
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ISSN:0196-2892
1558-0644
DOI:10.1109/TGRS.2025.3552114