Fresnel diffraction of multiple disks on axis
| Autor: | Claude Aime |
|---|---|
| Přispěvatelé: | Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) |
| Rok vydání: | 2020 |
| Předmět: |
010504 meteorology & atmospheric sciences
Astrophysics 01 natural sciences methods: analytical Convolution symbols.namesake Optics instrumentation: high angular resolution 0103 physical sciences Arago spot space vehicles: instruments Envelope (mathematics) 010303 astronomy & astrophysics 0105 earth and related environmental sciences Physics Sun: corona business.industry Stray light Plane (geometry) Fourier optics Astronomy and Astrophysics Conical surface 13. Climate action Space and Planetary Science symbols [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] business Fresnel diffraction |
| Zdroj: | Astronomy and Astrophysics-A&A Astronomy and Astrophysics-A&A, EDP Sciences, 2020, 637, pp.A16. ⟨10.1051/0004-6361/201937208⟩ |
| ISSN: | 1432-0746 0004-6361 |
| Popis: | Aims. We seek to study the Fresnel diffraction of external occulters that differ from a single mask in a plane. Such occulters have been used in previous space missions and are planned for the future ESA Proba 3 ASPIICS coronagraph. Methods. We studied the shading efficiency of double on-axis disks and generalized results to a 3D occulter. We used standard Fourier optics in an analytical approach. We show that the Fresnel diffraction of two and three disks on axis can be expressed using a Babinet-like approach. Results are obtained in the form of convolution integrals that can be written as Bessel-Hankel integrals; these are difficult to compute numerically for large Fresnel numbers found in solar coronagraphy. Results. We show that the shading efficiency of two disks is well characterized by the intensity of the residual Arago spot, a quantity that is easier to compute and therefore allows an interesting parametric study. Very simple conditions are derived for optimal sizes and positions of two disks to produce the darkest structure around the Arago spot. These conditions are inspired from empirical experiments performed in the sixties. A differential equation is established to give the optimal envelope for a multiple-disk occulter. The solution takes the form of a simple law, the approximation of which is a conical occulter, a shape already used in the SOHO Mission. Conclusions. In addition to quantifying expected results, the present study highlights unfortunate configurations of disks and spurious diffractions that may increase the stray light. Particular attention is paid to the possible issues of the future occulter spacecraft of ASPIICS. |
| Databáze: | OpenAIRE |
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