Design and analysis of the mirror system with off-axis field-of-view

Romanova, Galina E.; Rodionova, Kseniia D.

doi:10.1117/12.2321288

Cited by 2 publications

(2 citation statements)

References 7 publications

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“…1 They enable an excellent correction of aberrations while being obscuration-free. 1,2 Compact and lightweight TMAs are particularly interesting for Earth observation applications where space segment dimensions is becoming a constrain. While the field-of-view (FOV) along the off-axis is limited, TMAs are optimized with a large FOV in the perpendicular direction.…”

Section: Introductionmentioning

confidence: 99%

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Stray light control and analysis for an off-axis three-mirror anastigmat telescope

Clermont

Aballea

2021

Opt. Eng.

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Off-axis three-mirror anastigmat (TMA) telescopes provide excellent correction of aberrations over a large field-of-view in one direction. In a push broom configuration, this lightweight and compact optical configuration enables high-performing imaging. Moreover, passive multi-spectral acquisition can be achieved using a filter stack positioned at the detector vicinity. Stray light is a typical limiting factor for instrument performance and its control is specific to the type of optical configuration. We describe the stray light control and analysis methods in an offaxis TMA. The design intends to control first-order scattering from non-optical surfaces and to block straight shots. This is achieved through usage of elements such as apertures and baffles, both internal and external to the instrument. It will be demonstrated that the aperture stop is a critical element, whose stray light contribution can be controlled with V-groove vanes. Impact of mirrors roughness, a manufacturing physical limitation, is evaluated by modeling the bidirectional scattering distribution function and computing the stray light distribution at the detector for point-like source illumination. We show that the scattering on the different mirrors broaden differently the spot size, as the successive mirrors focus or expand the scattered rays differently. Finally, the ghost reflections inside the filter stack are evaluated and we show that there is no cross-talk between the different channels.

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Section: Introductionmentioning

confidence: 99%

“…While the field-of-view (FOV) along the off-axis is limited, TMAs are optimized with a large FOV in the perpendicular direction. [1][2][3] In a push broom configuration, the large FOV scans the Earth in the across-track (ACT) direction. Along-track (ALT), the instrument looks at the same area of the Earth with a very small temporal shift.…”

Section: Introductionmentioning

confidence: 99%

Stray light control and analysis for an off-axis three-mirror anastigmat telescope

Clermont

Aballea

2021

Opt. Eng.

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Stray light correction method for telescopes with linear detector arrays in push-broom configuration: application to CO2M-CLIM

Clermont,

Algoedt,

Lesschaeve

2024

Opt. Eng.

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Telescopes employing linear detector arrays in a push-broom configuration enable the reconstruction of two-dimensional images of the Earth by recombining successive one-dimensional captures. This configuration, which typically features a wide field of view in the across-track direction but a narrow one in the along-track direction, often suffers from stray light, which degrades optical quality by introducing artifacts into the images. With increasingly stringent performance requirements, there is a critical need to implement effective stray light (SL) correction algorithms in addition to control by design. We describe the development of such an algorithm, using the cloud imager (CLIM) linear detector array instrument as a case study. Our approach involves calibrating SL kernels obtained by illuminating the instrument with a point-like source from various angles. In the along-track direction, we interpolate the SL kernel for any field angle without initial assumptions about SL behavior. For the across-track direction, we employ a local shift variant assumption. When applied to images of a checkerboard scene, which includes transitions between bright and dark areas, our algorithm successfully reduces SL by two orders of magnitude, demonstrating its efficacy and potential for broader application in telescopes with linear detector array.

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Design and analysis of the mirror system with off-axis field-of-view

Cited by 2 publications

References 7 publications

Stray light control and analysis for an off-axis three-mirror anastigmat telescope

Stray light control and analysis for an off-axis three-mirror anastigmat telescope

Stray light correction method for telescopes with linear detector arrays in push-broom configuration: application to CO2M-CLIM

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