Stray light entrance pupil: an efficient tool for stray light characterization

Clermont, Lionel; Michel, Céline; Blain, Pascal; Loicq, Jérôme; Stockman, Yvan

doi:10.1117/1.oe.59.2.025102

Cited by 11 publications

(8 citation statements)

References 5 publications

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“…An alternative is to use a smaller collimator with square pupil and to scan the instrument entrance aperture, with no gap or overlaps. Significant gain in time is achieved by scanning only over the stray light entrance pupil [28,29] (SLEP), which represents the areas of the entrance aperture to illuminate in order to measure all the possible SL paths. The source diameter at the OAP focal plane as well as the OAP focal length are set such that the collimated beam has an angular width smaller than a pixel at instrument level.…”

Section: Calibration Of Spst Mapsmentioning

confidence: 99%

Stray Light Correction Algorithm for High Performance Optical Instruments: The Case of Metop-3MI

2022

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Stray light is a critical aspect for high performance optical instruments. When stray light control by design is insufficient to reach the performance requirement, correction by post-processing must be considered. This situation is encountered, for example, in the case of the Earth observation instrument 3MI, whose stray light properties are complex due to the presence of many ghosts distributed on the detector array. We implement an iterative correction method and discuss its convergence properties. Spatial and field binning can be employed to reduce the computation time but at the cost of a decreased performance. Interpolation of the stray light properties is required to achieve high performance correction. For that, two methods are proposed and tested. The first interpolate the stray light in the field domain while the second applies a scaling operation based on a local symmetry assumption. Ultimately, the scaling method is selected and a stray light reduction by a factor of 58 is obtained at 2σ (129 at 1σ) for an extended scene illumination.

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Section: Calibration Of Spst Mapsmentioning

confidence: 99%

Stray Light Correction Algorithm for High Performance Optical Instruments: The Case of Metop-3MI

2022

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“…In the case of IF illumination, it was shown that up to 90% of the SL comes from ghosts generated after the aperture stop and are mostly localized around the nominal pixel. 20 For OOF illumination, light is vignetted by the front baffles or the aperture stop; therefore, significantly fewer ghosts are formed. In that case, the aperture stop does not introduce vignetting, and many ghosts are present.…”

Section: Stray Light In 3mimentioning

confidence: 99%

“…4(a) and 4(b) show, the OOF SL is significantly smaller than the IF SL. In the case of IF illumination, it was shown that up to 90% of the SL comes from ghosts generated after the aperture stop and are mostly localized around the nominal pixel 20 . For OOF illumination, light is vignetted by the front baffles or the aperture stop; therefore, significantly fewer ghosts are formed.…”

Section: Stray Light Simulationmentioning

confidence: 99%

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Out-of-field stray light correction in optical instruments: the case of Metop-3MI

Clermont,

Michel

2024

J. Appl. Rem. Sens.

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In high performance optical instruments, post-processing methods are employed to reduce the stray light (SL) level below what can be achieved by design. Often, algorithms are limited to SL coming from sources located inside the field of view (FOV) of the instrument; however, SL could also come from sources located outside the FOV. We describe a method for correcting out-of-field SL, in particular for the case of the Earth observation instrument Metop-3MI. The proposed approach is a variant of the in-field (IF) method developed previously. We estimate the out-of-field SL by a linear combination of the SL kernels modulated by the input scene radiance. The correction is computed for fields on a regularly spaced polar grid, providing reasonable variations of the solid angle sustained around individual fields. Compared with the case of IF SL correction, a difficulty is that the out-of-field input radiance is unknown. We implement a mirroring technique, which is shown to be effective in most situations. This method will be used to correct the in-flight data of Metop-3MI, hence providing an SL level sufficiently low to fulfill the mission requirement.

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Section: Calibration Of Spst Mapsmentioning

confidence: 99%

Stray Light Correction Algorithm For High Performance Optical Instruments: The Case Of Metop-3MI

Clermont¹,

Michel²,

Stockman³

2022

Preprint

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Stray light is a critical aspect for high performance optical instruments. When stray light control by design is insufficient to reach the performance requirement, correction by post-processing must be considered. This situation is encountered for example in the case of the Earth observation in-strument 3MI, whose stray light properties are complex due to the presence of many ghosts dis-tributed on the detector array. We implement an iterative correction method and discuss its con-vergence properties. Spatial and field binning can be employed to reduce the computation time but at the cost of a decreased performance. Interpolation of the stray light properties is required to achieve high performance correction. For that, two methods are proposed and tested. The first interpolate the stray light in the field domain while the second applies a scaling operation based on a local symmetry assumption. Ultimately, the scaling method is selected and a stray light reduction by a factor of 58 is obtained at 2σ (129 at 1σ) for an extended scene illumination.

show abstract

Stray light entrance pupil: an efficient tool for stray light characterization

Cited by 11 publications

References 5 publications

Stray Light Correction Algorithm for High Performance Optical Instruments: The Case of Metop-3MI

Stray Light Correction Algorithm for High Performance Optical Instruments: The Case of Metop-3MI

Out-of-field stray light correction in optical instruments: the case of Metop-3MI

Stray Light Correction Algorithm For High Performance Optical Instruments: The Case Of Metop-3MI

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