Disruptive technologies to trigger science discoveries · • Toric: Simple combination of a sphere...

Disruptive technologies

to trigger science discoveries

Emmanuel HUGOT

Laboratoire d’Astrophysique de Marseille

EWASS 2017 - Plenary talk, June 28th, 2017

Outline

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Chapter 0: The Era of Giants

Large telescopes and related challenges

Chapter I: Stress polished toric mirrors

Contribution to the VLT SPHERE planet finder

Chapter II: Curved and deformable detectors

Focal planes, make them active

3

The Era of Giants: challenges

ELT instrumentation

Science drivers: farthest galaxies, faintest exoworlds, ...

Focal plane station = Size of a VLT unit (!)

VLT SPHERE: 20m3 E-ELT HARMONI ~100m3

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The Era of Giants: challenges

Beyond current limitations New paradigms

Wish list

Cryogenic environment (IR)

High throughput & stability

High angular resolution

PSF uniformity in the field

And more:

Multiplex

Broad wavelenght range

Low noise/large formats detectors

...

ELT instrumentation

Science drivers: farthest galaxies, faintest exoworlds, ...

Focal plane station = Size of a VLT unit (!)

VLT SPHERE: 20m3 E-ELT HARMONI ~100m3

Towards efficient instrumentation

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Collimator: 4 lenses

Camera: 6 lenses

Grating

No collimator

Camera: 1 freeform(!)

Grating

From Cuby+ 2006 inc. Hugot

Only 2 mirrors

Volume gain x5

Throughput gain 20%

No chromaticity

Simplified AIT phase

Length: 2.0 m

Length: 0.6m

Conventional

spectrograph

The price to pay

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150mm

Detector2k x 2k

F/4 beam

F/16 beam

2. Flat field, large detector Increased optics complexity

Overcome fabrication limits

Make them active

Curve the focal plane

1. Extreme freeform shape10 times higher than state of the art

6mmdeviation

Required optical quality <100nm

Telescopes evolutionThe advent of Active optics

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Active telescopes

Refractive

Reflective, Monolithic

Reflective, Segmented

Dia

me

ter

[m]

Year

Active telescopes

From Bastait, 2010

NTT: New Technology TelescopeThe first active telescope

Wilson+1991

FOCUS ON…

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Active OpticsStress polishing of theSPHERE toric mirrors

in collaboration with the SPHERE consortium ESO press release 2012

10

High contrast imaging

Extreme AO 90% Strehl in H band

Coronagraph for starlight extinctionContrast 106 – 108

Off axis optical designAvoid diffraction effects

Crédit ESO

HR 4796A Iota Sgr

Exoplanet imaging: VLT-SPHERE

Three Toric mirrors+

Active Optics system 41 x 41 actuators Deformable mirror

SPHERE on the VLT-UT3 Nasmyth platform

Beuzit+ 2014Fusco+ 2006Dohlen+ 2012Sauvage+ 2016Vigan+ 2010…

Tip Tilt


Three Toric mirrors+

Active Optics system

High order deformable mirror

11Crédit ESO

HR 4796A Iota Sgr

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Dealing with residual speckles


Due to AO, randomly distributed, will average out during a ~ 1 hour exposure Due to static aberrations:

will remain in the image plane and limit the high contrast performance

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Dealing with residual speckles


HiF errors

MidF errors

Tiny static speckles come from optical surface errors Image plane = frequency domain

mid frequency errors = performance loss

HIGH CONTRAST IMAGING&

STRESS POLISHING

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Stress polishing principle

Step 1: Substrate warping

Into the inverse form you want to reach

Step 11: Spherical grinding/polishing

Using full size tools and Imprint the warping function

Step 111: Removal of the loads

Get your aspherical surface at rest

Gain:High quality off axis surfacesNo sub aperture tool marks

Perfectly suited for High contrast imaging

• Three Toric mirrors in the AO common path

• Toric: Simple combination of a sphere + astigmatism,

VLT-SPHERE Toric mirrors

Astigmatism generation

2 pairs of equal and opposite forces

Variation of the radius of curvature in 2 orthogonal directions

Basic solution generates radial and angular harmonics

Solve this problem:

Two thickness substrate (external thick ring) get rid of radial harmonics

Angular thickness distribution get rid of angular harmonics

Topological optimisation: optimise the mechanical warping down to nanometric precision

Analytical model – FEA validations

Hugot et al Applied Optics 2009

Warping ~20µm Residuals <3nm RMS

Analytical definition Finite element analysis Interferometric validation

Solve the inverse problem

Blanks and warping harness

TM3 – 396mm

TM1–174mm

TM2-40mm

TM1+deformation system Spherical pitch lap

Three substrates:

Diameters 174mm, 40mm, 396mm

Deformation system:

Circular ring attached to the back

+ 2 micro-screws to warp the system

Super-polishing results

Exquisite results

Form errors ~10-20nm RMS

Ultra-low HF level ~1-2nm RMS

Sub-nm roughness ~5 Angströms

Delivered to SPHERE in 2011

+ one spare in 2013


Exquisite results





+ one spare in 2013

Hugot+2009 (App. Opt.)Hugot+2012 (A&A)


Exquisite results





+ one spare in 2013

Hugot+2009 (App. Opt.)Hugot+2012 (A&A)

BUT…

Next step: Active Toric Mirror

Big issue: ageing of High Order DM

Large amount of Cylindrical bending

14.45µm @ 20°C !

Strongly reduces the dynamic of the HODM (~20µm)

Evolves with temperature and hygrometry…

Solution:

Install a warping harness on TM3 for cylinder compensation

Shape optimization with FEA:

the influence function of one actuator generates the required cylinder

Next step: Active Toric Mirror

Compensation results on SPHEREXAO now fully functional

Work done with:

Sabri Lemared, Anais Bernard, Zalpha Challita, Jean Luc Beuzit,

Jean François Sauvage, Anne Costille, Thierry Fusco, Kjetil Dohlen

Installing the active TM3 inside SPHERE

AO off AO on

94% strehl @ 1.65µm

HODM 20°C HODM + TM3@3mic HODM + TM3@10mic

On-sky demonstration of the complementarity

between active and adaptive systems

Motorization system

Hugot+2008, Sauvage+ 2016Lemared+ 2016

NASA-STScI / HiCat mirrors

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HiCat = high contrast platform @ STScI

Same challenges as on SPHERE, in terms of surface quality

Delivery of 3 super-polished off axis mirrors in 2013

O34 O7 O8

LoF WFE [nm] 13.0 7.0 6.4

MiF WFE [nm] 1.5 2.0 1.5

HiF WFE [nm] 1.3 2.2 1.6

Roughness [nm] 0.4 0.5 0.4

Exquisite results too:

Only 12nm WFE after 15 optics!

N’Diaye, Soummer+ 2014

NASA-STScI / HiCat mirrors

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HiCat = high contrast platform @ STScI

Same challenges as on SPHERE, in terms of surface quality

Delivery of 3 super-polished off axis mirrors in 2013

proof

Feasibility study

FOCUS ON…

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Curved detectorsPhD Delphine DUMAS 2009-2012Post doc Yann GAEREMYNCK 2013-2015PhD Wilfried JAHN 2015-2017PhD Christophe GASCHET 2016-2018PhD Mélanie ROULET 2017-2019Post doc Simona LOMBARDO 2017-2019

in collaboration with

Curved µbolometer array

Dumas, Fendler et al. 2012

Multi-CMOS curved array

Chambion+ 2016 inc. Jahn&Hugot

Breaking News: just delivered!

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20 Megapixels, 24 x 32mm² full frame VIS curved CMOS sensorRadius: 150mm, Concave

Fully functional, in its original packaging

Optical systems and curved focal planes

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Stamenov+2015, Applied Optics

Comparison between fisheye objectives and monocentric systems

Flexible focal plane arrays

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Lab proto

Pre-indus proto

The Fish eye exercise

Two optimized optical designs

Based on a CANON patent

One lab prototype

One pre-industrial demonstrator

Dramatically increased optical quality up to 50% Save about 30% of optical surfaces

Chambion, Jahn, Hugot et al 2015

Canon DesignFlat focal plane

14 lenses – 11 materials

LAM/LETI design #1Concave variable FP


LAM/LETI design #2Convex sensor


Patented design


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Lab proto

The Fish eye exercise

Two optimized optical designs

Based on a CANON patent

One lab prototype

One pre-industrial demonstratorChambion, Jahn, Hugot et al 2015

Canon DesignFlat focal plane


LAM/LETI design #1Concave variable FP


CAD design interfaced with Canon Camera

Pre-indus proto

LAM/LETI design #2Convex sensor


Patented design

MANUFACTURING THE DEFORMABLE CURVED DETECTORS

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Existing solutions

Mosaic FPA with flat detectors

Kepler focal plane

Monolithic VIS 4kx4k

Iwert +2011ESO + UofA development

Curved µ bolometer array

Dumas, Fendler +2012

350 x 256 pix, @11µm

Curved IRCMOS

Tekaya, Fendler +2014

Functional @80K!

Spherical Radius 80 mm

Spherical Radius 250 mm

Aspherical shape

Sony, Itonaga+2014

Curved image sensors

Microsoft, Guenter+2017


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Gain

Control the bending of the substrates

Reach any curvature before breakage

Test performance over a broad range of curvature

Simplify manufacturing process?

PrincipleCombine active mirrors and flexible arrays

Ferrari 1998, A&A Variable Curvature mirrors for the VLTI

Curved single chip prototypeOn deformable substrate


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Extensive simulation on (100)-oriented silicon plates to extract:

min. allowable Radius achievable before breakage limit

On top and bottom surface of the detectors

For different thicknesses

Outputs:

Confirm previous results

Allowed to extract Regions of

Interest

Other type of simulations on

different structures

(confidential)

Performance comparison flat/curved

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Functional CMOS sensor on 150mm curvature radius Small curvature impact on electro-optical response

Data sheet Flat SensorR=150

Curved sensor

Conversion coefficient 0,25 DN/e- 0,24 DN/e- 0,22 DN/e-

Dark noise 8 e- 9 e- 9 e-

Dark current (25°C) 125 e-/s 119 e-/s 169 e-/s *

*Extrapolated valuesConsidering +12,5%/°C

Full characterization on going at CEA, results to be confirmed next month.Stay tuned!

Project-wise roadmap• FOCUS ANR program 2012-2016

– Development of prototypes

– Realization of optical systems

• ERC program 2016-2021

– PhD and Post doc position

– A 350k CFT to be issued for prototypes realization next year

– Leverage to structure activity with ESO and ESA?

• ANR program 2017-2020

– Ground based demonstrator – Schmidt telescope

– Opportunity to have a psychological impact

with an on-sky system

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Pre-indus proto

LAM/LETI design #2Convex variable FP

N lenses – N materials

Agencies• ESO directorate of engineering

– Visit @ LAM in Oct. 2016

– Working on a super-MUSE like concept, no optical solution without curved

detectors

– This R&D is identified as a priority

• ESA roadmap

– Discussions with ESO direction of engineering

– GSTP on curved detectors already identified

• NASA roadmap

– Curved detectors listed in potential breakthrough technologies in the decadal

survey currently ongoing.38

CURVED DETECTORSsoon off-the-shelf, soon on the E-ELT, soon in space?

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Curved VIS prototypeOn deformable substrate

Curved bolometerRc = 80 mm

Curved IRCMOS Rc = 250 mm

Gaschet, Jahn, Hugot, Ferrari et al 2017 in prep.

Highly curved VIS CMOS detectorRc = 150mm

Dumas et al 2012 Hugot et al 2016

Tekaya et al 2014

Disruptive technologies to trigger science discoveries · • Toric: Simple combination of a sphere...

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