FAME - astro-opticon.org · Actuators/Sensor Inventory prepared Metrology Ideas present ‐Actuator verification (local) ‐PSF analysis (for large deviation) ‐PD when errors sufficiently

FAME

Freeform Active Mirror Element (WP5)OPTICON Board

Granada, Oct 29th 2014

On behalf of the FAME team:ATC: Martin Black, Chris Miller, Hermine SchnetlerKonkoly Observatory: Evelin Banyai, Attila JaskóLAM: Zalpha Challita, Emmanuel HugotNOVA‐ASTRON: Tibor Agócs, Gabby Kroes, Lars Venema (+ Felix Bettonvil, Rik ter Horst)

FAME/GRANADA – LARS VENEMA 2

OUTLINEClassic freeforms, extreme freeforms, active freeforms,

Definitions, overview and interests

I. FAME optical design studyF/2‐4, 7x5.4deg, 2‐mirrors design and performance

II. FAME optical fabrication studyHydroforming thin freeform shapes: FEA and experiments

III. FAME optical active array studyopto‐mechanical design, FEA and performance

IV. Metrology and controldepending on tools developed in III – local and global

Towards an integrated system

Programmatics

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GOALFreeform Active Mirror production development to

simplify systems complexity and boost performance of (Astronomical) optical systems

Opticon Phase 2 – a strong focus on realizing FAME

• WP 5.1: System studies, E‐ELT instrument optimisation• WP 5.2: Conception, simulations and preparatory tests of

models• WP 5.3: Manufacturing, assembly, integration and

performance characterisation of the Active Freeform Mirror



INCREASING FOCUSActive mirrors used in industry

ASML, Power laser systems, Drone applications (AO‐DMs useless)

Active Optics in SpaceRecent ESA tender: “(cryogenic) deformable mirror and correction”Many parties interested: University of Münster – Thales – TNO –LAM – NOVA ‐ …

Extreme shapesGenerally specials – Used in molds (mobile phones) ‐ beamers

Problem for general approachEach application has very different requirements

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MOTIVATION OF PARTNERS

6

Active Optics

Freeform Optics

Non Pupil plane correction

Cryogenic

Space Optics

Primary Observing Path Metrology

Long Term Stability


DEFINITIONSClassic Freeform

No‐rotational symmetryNot defined by conicoids

Extreme FreeformA freeform with a deviation from the BFS higher than 100µm on small diameters

Active FreeformCombining extreme freeforms and deformable mirrors R&D developments on optical design, opto‐mechanics, optical fabrication, control/command

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Provided by any good deformable mirror on

the market

THIS is a challenge!

Manufacturing issues


Face sheet

Active Array

Actuation Layer

BREAKDOWN


OPTICAL DESIGN(SELECTION)


PAST• non‐Zernike polynomial extension for ZEMAX• Optimization method limiting and steering DOF in design• Developing translation method projecting wfe of pupil plane to location of

actual optics

DEVELOPED TOOLS


METISmid‐IR instrument for the EELT – impact of freeform on design

MOS SpectroscopeA freeform with a deviation from the BFS higher than 100µm on small diameters

Extreme systems (3 freeforms in one system)Work also done by CeFO very nice but also expensive

CASES


3‐freeform mirrors f500No central obscurationNo corrective field lensFlat focal planeDistortion free,Diffraction limited 0.2µm – 1µmField 2x4 deg²

F/4 THREE FREEFORMS DESIGNBased on Fürschbach system (2011)Uses extreme freeform mirrors (sag BFS:1.2 – 1.3 mm and 0.4 mm respect.

x (mm)

y (m

m)

Residuals

-60 -40 -20 0 20 40 60

-60

-40

-20

0

20

40

60

0

0.2

0.4

0.6

0.8

1

1.2

x (mm)

y (m

m)

Residuals

-80 -60 -40 -20 0 20 40 60 80

-80

-60

-40

-20

0

20

40

60

80

0

0.2

0.4

0.6

0.8

1

1.2

x (mm)

y (m

m)

Residuals

-100 -50 0 50 100

-100

-50

0

50

100

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4


“METIS” SPECTROMETER• DL at shortest λ• Except extreme• corners• Optics costly

• Alternatives:Better quality


“METIS” “VERSION 2”Move all complexityinto one component

Optical quality“improved”

Sag

Deviation from BFSIs 0.06mm PV


“MOS” TYPE SYSTEM

Deviation fromBFS is 0.06mm PV

Sag

Only one non sphericalMirrorPerformance very good


F2‐4* TWO MIRROR SYSTEMCompact freeform based optical system (re‐imaging systems)

Very good image qualityFast F‐ratio

Freeform mirror M2Size 100mm diameterDeviation from BFS: 0.3mm PVHandled in ZEMAX:

Optimized set of Zernike

Testing & controlUsing the optical system itselfAccessible entrance pupil for Phase diversity

* Made slower to fit det. pixels

M2 (freeform)

Entrance pupil 25x12.5mm² M1 Convex

oblate ellipsoid

7x5.4deg²

For 1.7µm pix, 3800x2700pix pix size = 6.6x7.2arcsec.


0

0,5

1

1,5

2

2,5

3

3,5

4

µm RMS

FAME M2 mid order terms (5µm RMS)

051015202530354045

µm RMS

FAME M2 freeform shape (60µm RMS)

00,050,10,150,20,250,30,350,40,45

X Tetrafoil

Y Tetrafoil

X Trefoil

Y Trefoil

X Astig

Y Astig

X Co

ma

Y Co

ma

Sphe

rical

X Pe

ntafoil

Y Pentafoil

X Tetrafoil

Y Tetrafoil

X Trefoil

Y Trefoil

X Astig

Y Astig

X Co

ma

Y Co

ma

Sphe

rical

µm RMS

FAME M2 high order terms (0.6µm RMS)

x (mm)

y (m

m)

Residuals (PV = 0.303347 mm)

-40 -20 0 20 40

-40

-30

-20

-10

0

10

20

30

40

-0.05

0

0.05

0.1

0.15

0.2

(5μm RMS) (0.6μm RMS)

(60μm RMS)

ZERNIKE DESCRIPTION


FACE SHEET


Active Optics techniquesBeyond the elastic limit: plasticizing

Permanent deformations Large sags extreme shape Elastic domain recovered active compensation system

High material history dependency need of simulations & experimentation High material history dependency need of simulations & experimentation In-situ actuation

[Hugot et al., 2012]

[Ferrari, 1998]

Elasticity theory

Circular plates

Rigidity

Large displacements

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thicknessntsdisplaceme

Dqz22

)ν-(112EtD 2

3

Variable curvature mirrors(VCM/VLTI delay lines)

Stress polishing (Sphere/VLT toric mirror)


Operating modeFast (few minutes) & simple

• Thin substrate• Specific mould• High hydraulic pressure

Optical interests No high spatial frequencies residuals

No tool-marks Low spatial frequencies actively compensated Flat or spherical polishing


Operating modeFast (few minutes) & simple

• Thin substrate• Specific mould• High hydraulic pressure

Optical interests No high spatial frequencies residuals

No tool-marks Low spatial frequencies actively compensated Flat or spherical polishing

Pressures:‐ deformation: 450 bars‐ clamping: 100 bars

zmould(vertex) = 13.397 mm zmirror(vertex) = 11.899 mm


EQUIPMENT

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Dedicated hydroforming engine• 700 bars hydraulic oil pressure • Clamping system with hydraulic jack• Adaptable mold shape/material

Internal cavity with blank‐holder

Mirror & mold integration

Mirror deformed after processing AISI420b stainless steel

1 mm & 2 mm thicknessestotal 140 mm


MANUFACTURING STEP – PLASTICIZED MIRRORS QUALITY

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Residuals

Mid aspherical mirror

Moderate aspherical mirror

Spherical mirror

• Full‐size tool polishing ‐ Roughness: 10 nm rms, Focus: 5 µm rms, Astig. : 3 µm rms• Thickness: 1 mm (case 3) & 2 mm (case 1 and 2) – AISI 420b stainless steel• Optical surface: 100 mm

RoughnessEVM stress repartition

70 20 nm rms

15 4 nm rms

8 1 nm rms

• Depart. from BFS:280 µm ptv66 µm rms

• F/0.5 aperture

• Depart. from BFS:61 µm ptv17 µm rms

• F/4 aperture

• Error from BFS:1.8 µm ptv0.38 µm rms

• F/10 aperture

◌ Optical performance: FEA vs. Experiment


MANUFACTURING STEP – ENJOY ;) !

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◌ Plasticizing operation needs 5 minutes◌ Tests realized on thickness 2 mm & 1 mm◌ Tests on 1.5 mm are in preparation


ACTIVE ARRAY


Aim of the active array within FAMEGenerate the full freeform shape or compensate for manufacturing errors

Face Sheet Deformation1. Towards additional stiff structure (Conventional AO mirrors)2. Reshaping stiff structure

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ACTIVE ARRAY


ACTIVE ARRAY ISSUES

Pillars distributionPattern optimizationRelated performance

Pillars shapeReduce print throughImprove influence function shape and surface generation

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PATTERN OPTIMISATION3 different shapesShearing actuators

Optimization based on gradient method + FEA

Directly inspired from optimized pattern developed @ CalTech(M. Laslandes SPIE 9148‐151)

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PERFORMANCE OF ARRAYS

Generated shape

Residuals

42 102 126Actuator count

lay‐out

15.1

μm RMS

61μm

RMS

8.7μm

RMS

4.5μm

RMS

62μm

RMS

62.5

μm RMS


REDUCTION D.O.F.53 38 actuators, removing those with less impact. The active 38 actuators are highlighted but the others’ stiffness is also taken into account ‐> uniform stiffness distributionPerformance similar – needs some further improvementRemoving Zernike Bias will reduce #actuators


ERROR BUDGET ON BUILDING BLOCKSOptical fabrication

Provide a freeform surface as accurate as possibleFocused on form generationNo high spatial frequencies

Target: WFE <50µm

Active ArrayProvide the second stage of freeform generation

Target: WFE < 1µmProvide a fine tuning of the surface Compensate for environment variations

Target: WFE <1µm

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ACTUATION LAYERActivities on hold – depends on final scale of system –

information available within few monthsActuators/Sensor Inventory preparedMetrology Ideas present

‐ Actuator verification (local)‐ PSF analysis (for large deviation)‐ PD when errors sufficiently small (first tests this year)

DemonstratorStarts next year – to be completed in 2016

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GLOBAL METROLOGYOne flavour of Phase DiversityPre‐selection ongoing

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TOWARD FAME PROTOTYPEOn going work

Identify actuators solutions Command Control systemInterface thin mirrors with active array ‐> manage the integration WFE

Issues to be addressedShape of pillars to reduce High spatial frequency residualsTwo stage approach for coarse and fine correctionsDesign a characterization test bed

PrototypingStarts next year – to be completed in 2016

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DEMONSTRATOR

Shack Hartmann sensor to validate principle

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~500 mmPupil


PLANNINGGGANT chart went wrong this week….

March 2015 – metrology and actuation layer design report

Start final design FAM(E) & demonstrator setup March 2015

Procuring, manufacturing, integration August 2015System ready for characterization and test January 2016Demonstrator @ SPIE June 2016

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OUTREACHPapers/presentations/posters @ conferencesPapers in scientific magazinsDemonstrator at SPIE 2016 (Edinburgh)

Technology TransferExpertise @ LAM often shared with industry to develop new technologies in industry (PhDs with confunding from Industry)Expertise @ ATC and NOVA shared with industrial partners

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PAPERSRefereed:Challita Z, et al., “Design and development of an active freeform mirror

for an astronomy application”, Opt. Eng. 0001;53(3):031311. (2014)

SPIE 2014E. Hugot et al, “Freeform Active Mirrors Experiment”Z. Challita et al, “Freeform mirrors and active optics: development of a

thin freeform manufacturing process for the FAME project”T. Agócs et al, “Freeform mirror based optical systems for FAME”A. Jaskó et al, “Active array design for FAME: Freeform Active Mirror

Experiment”

ICSO 2014T. Agócs, R. Navarro, L. Venema, “Variations on a theme: Novel

Immersed Grating Based Spectrometer Designs For Space”

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MEETINGSKick Off 26/27‐03‐2013TM1 02/03‐10‐2013TM2 11/12‐02‐2014TM3 02/03‐09‐2014

Great team!!!

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CONCLUSIONSWell on track

Very important partial results achieved – tools developed

Budget is very tight, but spending match expectations

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HORIZON 2020Active Optics and Freeform Optics become even more

importantShould consider how to shape this in the European context?

Cf. American example – concentrate on specific Optical problem

Extend into space and cryogenic development…Explore Additive manufacturing Capabilities (3D printing of

lightweight structures, Mirror substrates, Layered materials)Active structures

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Documents

FAME - astro-opticon.org · Actuators/Sensor Inventory prepared Metrology Ideas present ‐Actuator verification (local) ‐PSF analysis (for large deviation) ‐PD when errors sufficiently