slides at NUVA meeting El Escorial Spain 2007

The Fresnel Diffractive Imager project
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Principles, Instrumentation and Mission scenarios
Laurent Koechlin,
Denis Serre,
Paul Deba,
Truswin Raksasataya,
Christelle Peillon,
Emmanuel Hinglais,
Paul Duchon,
Pierre Etcheto,
Christian Dupuy,
Benoît Meyssignac,
Laurent Doumic.
Université
de Toulouse,
CNRS France

The Fresnel Diffractive Imager project
I. Optical Principles
Focalization by diffraction
Chromatic correction
High dynamic range
III. Space mission scenarios
Primary array vessel design
Focal instrumentation design
Orbits and Formation flying configuration
IV. Astrophysical targets
Some of the possible scenarios
II. Lab prototype, optical and numerical tests
Optical setup
Tests results on artificial sources
Tests planned on sky sources
Numerical simulations for large arrays

I. Optical Principles

focus
Order 0 :
plane
wave
Lens (or miror): focusing by refraction (or reflexion)
Fresnel array: focusing by diffraction …
Focalization : different ways
Plane wavefront
Order 1 :
convergent
focus
Lens

Concentric geometry (Soret 1875)
Efficiency at order 1: 10%
Exemple for
15 Fresnel zones
2D radial expansion