Versatile full aperture illumination OGSE Setup for alignment and end-to-end calibration of the EnMAP hyperspectral image

Lettner, M.; Lamour, Tobias P.; Polz, Leonhard; Glastre, Wilfried; Compain, Eric; Fischer, Sebastian

doi:10.1117/12.2536148

Cited by 6 publications

(8 citation statements)

References 3 publications

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“…With completion of the instrument optics unit planned for end of this year, the in-depth characterization of the complete optical chain will start. These test activities will make use of a highly modular, custom made optical GSE concept [4]. After finalization of the instrument optics unit the remaining functional subunits will be integrated.…”

Section: Discussionmentioning

confidence: 99%

EnMAP: hyperspectral Imager (HSI) for Earth observation: current status

Mücke

Sang

Heider

et al. 2019

International Conference on Space Optics — ICSO 2018

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The Environmental Mapping and Analysis Program (EnMAP) is a German space borne science mission that aims at characterizing the Earth's environment on a global scale. The single payload of the satellite is the Hyperspectral Imager (HSI). It is capable of measuring the solar radiance reflected from the Earth's surface as a continuous spectrum in the spectral range of 420nm to 2450nm, with a spectral sampling of 6.5nm (VNIR) and 10nm (SWIR). The EnMAP swath of 30km is sampled in spatial direction with 30m GSD.In this proceeding, we give an overview of the design and current integration status of the HSI instrument optical unit with additional focus on measured optical and electro-optical performance.

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Section: Discussionmentioning

confidence: 99%

EnMAP: hyperspectral Imager (HSI) for Earth observation: current status

Mücke

Sang

Heider

et al. 2019

International Conference on Space Optics — ICSO 2018

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“…Modular OGSE approach For higher flexibility in the AIT process, a modular OGSE approach was chosen, with separated light sources and illumination optics [3]. As a connection between both, standardized fibre optic interfaces have been used.…”

Section: Virtual Conference 30 March-2 April 2021mentioning

confidence: 99%

“…Figure 4 shows the setup for this TA to ISU alignment. The TA entrance pupil was illuminated with a collimated light beam of 200 mm diameter coming from the Full Aperture Illuminator (FAI) [3]. The light was focused by the TA onto the FSSA and was reflected back by micro-mirrors on the FSSA [2].…”

Section: Telescope Assembly (Ta) To Instrument Spectrometer Unit (Isu) Alignmentmentioning

confidence: 99%

Setups for alignment and on-ground calibration and characterization of the EnMAP hyperspectral imager

Polz

Serdyuchenko

Lettner

et al. 2021

International Conference on Space Optics — ICSO 2020

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The Environmental Mapping and Analysis Program HyperSpectral Imager (EnMAP HSI) will allow to acquire images of the Earth surface in a push-broom configuration. Spectral coverage includes 230 wavelength bands between 420 nm and 2450 nm, which are simultaneously recorded with a ground resolution of 30 m x 30 m.High requirements on the optical alignment of the Visual Near InfraRed (VNIR) and Short Wavelength InfraRed (SWIR) spectrometers and cameras have been fulfilled (one pixel lateral alignment and below 20 μm for defocus). In addition, a calibration and characterization campaign of the EnMAP HSI was performed, with the aim to verify the instrument requirements and to quantify its performance. The campaign addressed the following five responsivity domains: radiometric, polarization, spectral responsivity, spatial responsivity and stray light. A spectral calibration accuracy of 0.5 nm for VNIR and 1 nm for SWIR channel, and lateral calibration of the full field-of-view with sub-arc second accuracy was achieved. For all measurements, traceability to national standards is guaranteed by comparative measurements with calibrated devices.The paper presents the setups of the alignment, calibration and characterization measurements of the EnMAP HSI. Instrument requirements on calibration accuracy are reported. The traceability to national standards will be described and the validation of measurement accuracy.

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“…Further details of the optical ground support equipment that will be used during the EnMAP characterisation can be found in Ref. 7.…”

Section: Light Coupling To Instrumentmentioning

confidence: 99%

Light source for stray light characterisation of EnMAP spectrometers

Pope

Baumgartner

2019

Sensors, Systems, and Next-Generation Satellites XXIII

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EnMAP is a German hyperspectral satellite mission. The Remote Sensing Technology Institute of the German Aerospace Center is responsible for the stray light characterisation of the satellite's spectrometers. This paper describes the light source developed for that purpose and how it will be employed to characterise the in-band, in-field stray light. This type of stray light can be characterised by measuring the point spread function (PSF) at multiple locations on the detector. Because of the cumulative effect of stray light, it is necessary to characterise the PSF in the near-and far-field. The PSF can span a range of more than 6 orders of magnitude from the peak to the wings at the edges of the detector, exceeding the intrinsic dynamic range of the instrument. Therefore a high dynamic range (HDR) PSF measurement is required: A spectrally and angularly narrow spot of light is guided onto the instrument then measurement frames of multiple signal levels are acquired. The signal level is controlled by changing the instrument's integration time or changing the neutral density filter of the light source. The overexposed pixels in the higher signal level frames are excluded, then the multiple image frames are combined into one HDR frame which can then be used in the stray light correction algorithm. This HDR 'bracketing' technique is demonstrated here with DLR's HySpex VNIR-1600 airborne imaging spectrometer.

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Versatile full aperture illumination OGSE Setup for alignment and end-to-end calibration of the EnMAP hyperspectral image

Cited by 6 publications

References 3 publications

EnMAP: hyperspectral Imager (HSI) for Earth observation: current status

EnMAP: hyperspectral Imager (HSI) for Earth observation: current status

Setups for alignment and on-ground calibration and characterization of the EnMAP hyperspectral imager

Light source for stray light characterisation of EnMAP spectrometers

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