the fresnel diffractive imager project --- principles, instrumentation and mission scenarios laurent...
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The Fresnel Diffractive Imager project---
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 projectI. 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 testsOptical 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
Orthogonal geometry (2005)
Efficiency at order 1: 4 to 8 %
2D Cartesian expansion
g(x)= 1 si (x2 +f2)1/2 [(f/m+ (k-off)+1) m ; (f/m+ (k-off)+1)
m[
sinon g(x) = 0Transmission (x, y) = g (x) xor g (y)
Fresnel Zone plate or Aperture synthesis array ? (here: 1740 ouvertures)
Exemple for 30 Fresnel zones
circular geometry => isotropic PSF
Image
Image formation
non linear luminosity scaleIn order to show the faint isotropic rings.
Aperture
Orthogonal geometry => orthogonal PSF
Transmission: g(x) g(y)
Image formation
non linear luminosity scaleIn order to show the faint spikes.
Image
Aperture
Quasi no stray light except in the spikes.
Case of a second source in the field:
Image formation
Image formation
Case of a second source in the field:
Image formation
Case of a second source in the field:
Comparison: Fresnel arrays versus a solid aperture
1500 Fresnel zones
Images of a point source by:
150 Fresnel zones
Solid square aperture
luminosity scale:Power 1/4 to show
spikes
"for" Fresnel Arrays:
No mirror, no lens to focalize : just vacuum and opaque material. => a potentially very broad operational domain: 90nm - 25 m
Large tolerance in positioning of subapertures for /20 wavefront quality:
100 m in the plane of the array10 cm in the wave propagation direction (perp. to
array)The tolerance is wavelength independent
=> Opens a way to build very large aberration-free apertures for astrophysics.
High dynamic range: 108 on compact objects for a 300 zones array
Angular resolution: as high as with a mirror the size of the whole array.
"against" Fresnel Arrays:
Chromaticity... corrected by small diffractive lens after focus, (order 1 chromaticity cancelled by order -1 chromaticity),but bandpass limitations remain: = √2 S/C
Low transmission compared to a mirror : t = 5 to 10%
kilometric focal lengths => requires formation flying in space
F = C2/8N
C
10 to 100 km
Optical scheme of the Fresnel Diffractive Imager
Diffractive lens at order -1
e.g. 10 cm Field Opticse.g. 2m
Img. plane 2 : achromatic
Primary Fresnel arraye.g. 20 m
pupil plane
Spacecraft 1 holding primary Fresnel array
Spacecraft 2 holding focal instrumentation
mask
image plane 1dispersed
Order 1 rays, focused by primary array
Order 0 rays
Converging lense.g. 10 cm
Focal Instrumentation
The field - bandpas compromise
Chromatically aberrated beam at prime focus
Field delimited by field mirror
The chromatic correctordoes a good job,but it corrects only what it collects.
II. Lab prototype, optical and numerical test results
Prototype built at Observatoire Midi Pyrénées in Toulouse2006 - 2008
Lab Prototype: light source module
• Étoiles doubles
photo
• Galaxies en spirales
photo
Gravure : Micro Usinage Laser.
mire 72 " d'arc
Exemples de sources test
Disque Ø 32 " d'arc
BinaireDisque Ø 0,8" d'arc
source test
Lab prototype: Fresnel array module
C = 8 cm
116 zones (26 680 apertures)
Opaque foil: inox 80 µm thick
Tested in the visible (450-850 nm)
F= 23 m for = 600 nm
Lab prototype, Focal module
Field "lens" Order 0 Mask Chromatic correction+ doublet focalization
Final image
23 m
Lab prototype, focal module, zoom on the corrector lens• 116 zones, 16 mm diameter, Blazed for 600 nm
• Fused silica
• Résolution selon le plan de la lentille de 1nm, hauteur des marches PTV 1.37 µm
• Ion beam etched (SILIOS), 128 levels,
• 1 m "location" precision, 10 nm "depth" precision
Diverging Fresnel lens mounted in the optical train
Qualitative results: images of artificial sources
uniform Disk 32 arc sec
uniform Disk 0.8 arc sec
Galaxy-shaped target 72 arc sec
broad spectral illumination: 550 - 750 nm
uniform Disk 0.8 arc secwith turbulence
double sourcehigh dynamic range
Quantitative results: measured angular resolution
Diffraction limited theoretical profile
Sampled optical point spread function
The prototype is quasi diffraction limited
Quantitative results: dynamic range optically measured versus numerically simulated
8 cm 116 zones
Optical image
8 cm 116 zonesNumerical Fresnel wave propagation
Through all the optical elements
In these saturated images of a point source, the average background is at 2 *10 -6
Luminosity scale
amplified x1000
Luminosity scale
amplified x1000
The numerical Fresnel propagation tool has been developed for testing large arrays
Quantitative results: PSF of a 300 zones Fresnel Imager (720 000 apertures)
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Not apodized, no order 0 mask
numerically simulated
Log dynamc range
Quantitative results: PSF of a 300 zones Fresnel Imager (720 000 apertures)
Apodized, order 0 masked
numerically simulated
Log dynamc range
Position in the field (resels)1/4 of the field represented
Log dynamc range
Quantitative results: PSF of a 300 zones Fresnel Imager (720 000 apertures)
Prolate apodized, order 0 masked
Beyond Orthogonality : improving transmission efficiency and dynamic range
directionnal " Spergle" type
Quantitative results: PSFs of non-orthogonal, square aperture imagers
luminosity scale:Power 1/4 to show
background
300 zones,Square aperturecosine apodized, order 0 masked
Quantitative results: Convolution simulations
300 zones, Square aperturecosine apodized, order 0 masked
HH_30BW, raw image (from HST)
HH_30BW, convoluted
The spikes do not degrade extended images
PSF
III. Space missions scenarios
To be proposed for the 2020-2025 period
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Not quite yet
XIXth century, 19 meter long, 76 cm Nice Obs refractor
Generation II prototype: tests on
high dynamic rangesky sources
Generation II prototype: tests on the sky
350 zones,20 cm aperture20 meter focal, 700 mas resolution106 or more dynamic range
To be built and operated 2008-2010, financed by CNES, subject of a present Ph.D. thesis
III. Space missions scenarios
Space Missions scenarios: Formation flying configuration
"lens" and "receptor" vessels for a 10m circular array configuration
Space Missions scenarios: Formation flying configuration
sat 10 à 30K100K
Mat isolent
V-groove
50K
simple pare soleil multi couches
structure type Astromesh
ressorts à forceconstante
difficulté de mise en œuvre (voir JWST)
sat 10 à 30K100K
Mat isolent
V-groove
50K
simple pare soleil multi couches
structure type Astromesh
ressorts à forceconstante
difficulté de mise en œuvre (voir JWST)
Principe des mesures (2x2 d.d.l. + F) :
1) Le « dépointage » du grand axe optique (Zopt) par rapport à la cible ZG est représenté parL. Il
permet d’estimer le déport latéral xL = F. L. Sa
figuration sur le plan focal du SSSL (ci-contre) est représenté par l’écart entre le motif des diodes laser implanté sur la grande lentille et la cible stellaire, caractérisée, en fait, par un « motif stellaire » avec ou sans la cible (cachée par la lentille en « contrôle fin »).
2) Le dépointage de l’axe optique du Récepteur par rapport au grand axe optique (R) est représenté par l’écart angulaire [ ZOR, ZOPT ].
3) Mesure de la distance Focale: En fin de phase d’acquisition, on estimera F à partir de la taille du motif de diodes laser. Par contre, la mesure fine de la focale sera effectuée par télémétrie Laser en phase de contrôle fin.
Space Missions scenarios: Navigation Control Scheme
Plan focal du SSSL dans l’Optique Réceptrice ZG (la
cible)Axe Optique du Récepteur :
ZOR
ZOPT (grand
axe optique)
R
L(= xL/F)
Lentille de Fresnel
Satellite Récepteur
Grand Axe « optique »
Olp
LP
Oor
Zopt
ZOR
R
ZG(étoile)
xL
Satellite Lentille de FresnelZL
P
FL
Schéma de principe de l’instrument distribué
Diode Laser
Space Missions scenarios: key parameters for spacecraft architecture
Orbit and mission- environment- Communications to ground- Vessel to vessel communications
- technology - fabrication- Lissajou orbits
TM/TC 2 par satellite terre/anti-terreLiaison RF sensing (type SimbolX) inter-satellite pour la formation
Moon
40°
SUN
Trajectoire typique montrant qu'au -delà de 100 000 km de la Terre,la MGA pointée comme le GS voit la Terre avec ses 40° d'ouvertur e
Moon
40°
SUN
Trajectoire typique montrant qu'au -delà de 100 000 km de la Terre,la MGA pointée comme le GS voit la Terre avec ses 40° d'ouvertur e
ecliptic plane
sun
small Lissajou
typically: period: 6 months
1 avoidable eclipse every 6 years
acceptable depointing angle of the line of sight = total shield angle protection – Earth, Sun and Moon covering (fonction of the L2 orbit)
sun
ecliptic planeEarth
Moon worst caseevery 28 days
L2
20
0 0
00
km
8°14°
Fresnel lenslight shield
line of sight
TMI Reflector Array (0 à 40°)1 on receptor spacecraft facing earth
fixed RA Antenna & GS Possible a partir de 100 000km from Earth
Space Missions scenarios: focal instrumentation
Intégration of science
and navigation channels:
privileged Scenarios
Space Missions scenarios: focal instrumentationchromatic correction optics
By réfraction By reflection
• NUV+VIS+NIR : lentille de Fresnel blazée à l’ordre –1 qui fonctionne en transmission, suivie d’un doublet convergent et achromatique technologie validée TRL04 : R&T CNES 2004-2007R&T CNES 2004-2007
• UV : miroir de Fresnel blazée à l’ordre –1 ayant double fonction : 1- Réseau correcteur en réflexion et hors axe. 2- Focalisation du faisceau par une concavité globale additionnelle
R&T CNES à venirR&T CNES à venir.
LFCLFC MFCFMFCF
IV. Astrophysical targets
Extra Galactic and Young Universe
Mission Physical Phenomenon Spectral Range (nm)
Dynamic Range within.
5 resels
Angular Resolutions
(mas)
Extra Galactic
lensing
Column density mapping
Black Body, Axion Ray Detection"
2000
500010-4 14 - 34
Extra Galactic
lensingColumn Density mapping, Black Body
600
200010-4 12 - 41
Extra Galactic to Z, Lyman Young Universe, Galaxy formation
1000
200010-4 7 - 14
Extra Galactic to Z, Lyman
breakRe-inonization period of the universe
600
120010-4 12 - 25
Color Code => Spectral Band : IR NIR Vis NUV FUV
Scientific Requirements
Extra Galactic and Young Universe
Mission D(m)
D, Field of View
(m)
Channel
Capture size and Bands
x y
Transfer Ratekbps
Amount captured
Images
Integrated time (h)
Mission Duration
(years)
Extra Galactic
lensing30 2
Pointing M2
2000*2000
3 bands11 4300 10 6,4
Extra Galactic
lensing10 1,2
Pointing M2
/Separation
2000*2000
3 bands11 9262 3 6,3
Extra Galactic at Z, Lyman 30 2
Pointing M2
2000*200010*10*2000
36 3993 20 8,9
Extra Galactic at z, Lyman break 30 2
Pointing M2
2000*200010*10*2000
11 9160 3 6,3
Instrumentation specifications t =3 h : for Changing Object t = 6 h :for Changing Spectral Band
Active Regions in Our Galaxy
Missions Physical Phenomenon Spectral Band (nm)
Dynamic range in 5
resels
Angular Resolution (mas)
Central Galactic Region, Dust and Globular Cluster
Density mass, Central Black hole,
I.R. absorption in interstella
2000
500010-4 14 - 34
Ionized density of Galactic Clouds,
Active Core
“Astrochemistry”
- Extra Galactic core
280
45010-4 6 - 9
Ionized density of Galactic Clouds,
Active Core
Astrochemistry, development of interstellar in Heavy element,
High Energy
120
28010-4 7 - 17
Scientific Requirements
Color Code => Spectral Band : IR NIR Vis NUV FUV Distance Between Objects : 0,2° - 0,5° No of Objects per spectral Band : 20
Active Regions in Our Galaxy
Mission Cgr(m)
D, Field of View
(m)
Channel
Capture size and Bands
x y
Transfer Ratekbps
Amount
captured
Images
Integrated time
(h)
Mission Duration
(years)
Central Galactic Region, Dust and Globular Cluster
30 2 Pointing M2 2000*2000
3 bands11 5192 120 7,7
Ionized density of Galactic
Clouds, Active Core
10 1,2 Pointing M2
/Separation
2000$200010*10*2000
21 6438 10 6,0
Ionized density of Galactic
Clouds, Active Core
3,5 0,6 Pointing M2
2000*200010*10*2000
43 4050 5 5,9
Instruments specifications
IR NIR Vis NUV FUV
Imagery Stellar and Circumstellar
With a 500 m array ?
Imagery Stellar and Circumstellar
Missions Physical Phenomenon Spectral Band (nm)
Dynamic range in 5
resels
Angular Resolution (mas)
Accretion disk, Jets, Photospheres
Evolution of stellar,Mass in Extreme conditions
13010-5
1
Pphotospheres and Circumstellar
Physic stellar 280-45010-5
15 - 29
Photospheres and Circumstellar :
Near objects
Physic stellar,
Circumstellar Clouds250 10-5 5
Photosphere et Circumstellar :
Far objects
Physic stellar,
Circumstellar Clouds250 10-5 2
Scientific Requirements
IR NIR Vis NUV FUV
Mission Cgr(m)
D, Field of View
(m)
Channel
Capture size and Bands
x y
Transfer Ratekbps
Amount captured
Images
Integrated
time (h)
Mission Duration
(years)
Accretion disk, Jets,
Photospheres30 2 none
4000*4000400*400*1000
43 2683 20 7,0
Photospheres, Circumstellar
3,5 0,6
Pointing M2
/Seperation
2000*2000400*400*400
213 19299 1 8,8
Photospheres, Circumstellar :
Near objects10 1,2 none
2000*2000400*400*400
213 23217 1 10,6
Photosphere, Circumstellar :
Far objects30 2 none
4000*4000400*400*1000
85 6191 10 9,2
Instrument Specifications
IR NIR Vis NUV FUV
Imagery stellar et circumstellar
ExoplanetsEarth @ 10 pc detection and spectroscopy
40m array, 300 Fresnel zones, PIAA, spectral resolution 50, 2*48h exposure time
"Exoplanets"
Missions Physical Phenomenon Spectral Band (nm)
Dynamic range
in 5 resels
Angular Resolution
(mas)
Exoplanets joviennes
Planets Systems,
atmospheres
600 -1200 10-8 17 - 25
Exoplanets telluric in IR
Planets Systems,
atmospheres
2000-5000 10-8 40 - 100
Exoplanets joviennes and
telluriques
Planets Systems,
atmospheres
600 -800 10-8 4 - 6
Exoplanets tellurics in IR
Planets Systems,
atmospheres
2000-5000 10-8 14 - 34
Scientific Requirements
IR NIR Vis NUV FUV
Exoplanets
Mission Cgr(m)
D, Field of View
(m)
Channel
Capture size and Bands
x y
Transfer Ratekbps
Amount
captured
Images
Integrated
time (h)
Mission Duration
(years)
Exoplanets 10 1,2 Point at M2
4000*4000300*300*100
71 6500 10 9,6
Exoplanets 10 1,2 Point at M2
4000*4000300*300*100
43 6300 10 9,4
Exoplanets 30 3 Point at M2
4000*4000300*300*100
213 4400 10 6,6
Exoplanets 30 3 Point at M2
4000*4000300*300*100
85 6000 10 9,0
Instruments Specifications
IR NIR Vis NUV FUV
¡Muchas gracias por su atencion!
Bonus slides
Achromatisation principle
Converging lensOperating at order -1