A new paradigm in the field of stray light control and characterization enabled by ultrafast time-of-flight imaging

Clermont, Lionel; Uhring, Wilfried; Georges, Marc; Khaddour, Wassim; Blain, Pascal; Mazy, Emmanuel

doi:10.1117/12.2629300

Cited by 3 publications

References 8 publications

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Unlocking stray light mysteries in the CoRot baffle with the time-of-flight method

Clermont,

Blain,

Khaddour

et al. 2024

Sci Rep

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Stray light (SL) has emerged as a primary limiting factor for space telescopes. Pre-launch testing is essential for validating performance and identifying potential issues. However, traditional methods do not enable the decomposition and identification of individual SL contributors. Consequently, when problems arise, resolving them often involves a cumbersome and risky trial-and-error approach. The time-of-flight (ToF) method was recently introduced, employing a pulsed laser source and ultrafast sensor to characterize individual SL contributors. A proof of concept was achieved using a simple three-lens system. In this paper, we apply the ToF method to a real space optical system: the spare model of the CoRoT baffle. We successfully measured individual SL contributors over a dynamic range of 10−11, identifying direct scattering on vane edges and two-step scattering paths. Our results provide a performance breakdown, differentiating intrinsic baffle SL from contributions arising from experimental conditions. Notably, the ToF method allowed us to discriminate air scattering, eliminating the need for expensive vacuum testing. The ToF provides unparallel insights, including defects identification. For instance, we identified the presence of localized dust particles causing significant SL. These results confirm the utility of the ToF method even for the most challenging space systems.

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Unlocking stray light mysteries in the CoRot baffle with the time-of-flight method

Clermont,

Blain,

Khaddour

et al. 2024

Sci Rep

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Automatic Internal Stray Light Calibration of AMCW Coaxial Scanning LiDAR Using Black and White Image Patterns

Lee,

Lim,

Kwon

et al. 2024

IEEE Trans. Instrum. Meas.

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Verification of straylight rejection of optical science payloads using a pulsed laser source

Ummel

Roulet

Holzer

et al. 2023

International Conference on Space Optics — ICSO 2022

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Helianthus is a technological development project funded by the Italian Space Agency for a Phase A study of a space weather station with solar photonic propulsion. Helianthus will have a synchronous orbit with the Earth-Moon barycenter, positioned at about 7 millions km from Earth towards the Sun, thus much closer to the Sun with respect to historical Space Weather instrumentation, which are typically orbiting the Earth or L1. This sub-L1 halo orbit is maintained by radiation pressure on a solar sail as the propulsion mechanism: once in flight, the spacecraft will have a huge square sail, about 40 m long. The scientific payload will be hosted at the center of the sail and will comprise remote-sensing and in situ instruments. Remote sensing: an X-ray detector to detect Solar Flares and SailCor, a coronagraph with a wide field of view. In situ: a plasma analyzer and a magnetometer. For this "Sailcraft", a scientific payload with reduced mass and envelope is under study. The maximum allowed mass for the entire scientific payload shall not exceed 5 kg. Both the X-Ray detector and the in situ instruments have a flight heritage. This study aims at developing a laboratory prototype of a coronagraph matching the constraints of mass and envelope of the Helianthus payload. SailCor is a 20 cm long coronagraph with a field of view ranging heliocentric heights 3-30 solar radii. The external occulter is mounted on an extendable boom that will be deployed once in flight. SailCor presents an innovative solution that combines the diffraction apodization by the external occulter and the internal occulter positioning so that no Lyot stop is required. The classical design of externally occulted coronagraphs foresees the positioning of an internal occulter as a conjugated element to the external occulter with respect to the primary objective. The function of the internal occulter is to block the image of of the diffraction from the external occulter edge. Then, a secondary objective generates the coronal image on the detection system. The SailCor solution takes advantage of the focusing effect that the entrance aperture of the instrument induces on the light diffracted by the external occulter. This effect is used to calculate the position of the internal occulter with respect to the primary focal plane. With this approach, there is no need for a Lyot stop and the detection system can be placed at the first focal plane, with a significant reduction of envelope and mass. This contribution describes the design of the prototype of SailCor, used in laboratory to experimentally define the geometry of the occultation system. The activity has been carried out in the INAF OPSys facility clean environment (ISO5/6) hosted at ALTEC S.p.A. (Torino). The source is a solar divergence simulator.

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A new paradigm in the field of stray light control and characterization enabled by ultrafast time-of-flight imaging

Cited by 3 publications

References 8 publications

Unlocking stray light mysteries in the CoRot baffle with the time-of-flight method

Unlocking stray light mysteries in the CoRot baffle with the time-of-flight method

Automatic Internal Stray Light Calibration of AMCW Coaxial Scanning LiDAR Using Black and White Image Patterns

Verification of straylight rejection of optical science payloads using a pulsed laser source

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