Compact multispectral and hyperspectral imagers based on a wide field of view TMA

Grabarnik, S.; Taccola, Matteo; Maresi, Luca; Moreau, Vincent; Vos, Lieve De; Versluys, Jorg; Gubbels, G.

doi:10.1117/12.2309101

Cited by 6 publications

(3 citation statements)

References 5 publications

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“…However, strict stray light requirements associated with the mission [17] and the need for efficient accommodation of the six detection channels called for an off-axis design of the limb instrument. Off-axis versions of TMAs have gained popularity [18][19][20][21][22], in part due to developments in mirror manufacturing where fully free-form metallic surfaces can be made using high-precision single-point diamond turning (SPDT) [23,24]. Unlike on-axis systems, the dominating aberration for off-axis telescopes is the lower-order linear astigmatism [25], which introduces a relative tilt between the tangential and sagittal image planes.…”

Section: Introductionmentioning

confidence: 99%

Wide-field off-axis telescope for the Mesospheric Airglow/Aerosol Tomography Spectroscopy satellite

et al. 2019

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We present the development of a compact f ∕7.3 (D 35 mm) three-mirror reflective telescope for the atmospheric-research microsatellite Mesospheric Airglow/Aerosol Tomography Spectroscopy (MATS). The telescope design was driven by the end users' need for a reflective wide-field (5.67°× 0.91°) optic with high stray light rejection and six detection channels with separate image sensors, operating at wavelengths 270-772 nm. For the first time, a design method for wide-field off-axis telescopes-in which linear astigmatism is eliminatedwas applied and tested in practice. Single-point diamond turning was used to produce two sets of 37-110 mm large free-form aluminum mirrors with surface figure errors and roughness values of 34-62 nm (RMS)/193-497 nm (PV) and 2.8-3.5 nm (RMS), respectively. A method that combines precise machining and geometry measurements (using a coordinate measuring machine) was employed to fabricate an aluminum structure to accurately position the mirrors without the need for manual alignment. The telescope was tested with a network of plate beamsplitters and filters, which define the spectral selection for the six detection channels. Imaging performance measurements were carried out using a reflective off-axis collimator, which projects imaging targets at infinite focus. A modulation transfer function (MTF) value of 0.45 at 20 lp/mm was measured at ∼760 nm (diffraction limit: 0.85) using a slanted edge target. By modeling the measured mirror surfaces in optical design software, a reoptimization of the mirror positions could be performed and an improved MTF of ∼0.75 at 20 lp/mm was predicted. The results demonstrate design-and building methods that can be utilized to make off-axis telescopes for a vast range of applications.

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Section: Introductionmentioning

confidence: 99%

Wide-field off-axis telescope for the Mesospheric Airglow/Aerosol Tomography Spectroscopy satellite

et al. 2019

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“…The amount of in-field stray-light and Modulation Transfer Function (MTF) degradation are therefore within requirements (see Section IV) [3]. 1 The Ground Pixel Size (GPS) is the footprint of a pixel on the ground.…”

Section: Icso 2012mentioning

confidence: 99%

“…Based on a PROBA small satellite platform, the three-axis stabilised satellite weights about 160 kg and has a volume of 800 x 800 x 1000 mm 3 . The main payload is the Vegetation Instrument (VI).…”

Section: Introductionmentioning

confidence: 99%