LATT:LargeApertureTelescopeTechnology

Xompero,M.,Briguglio,R.,Lisi,F.,Arcidiacono,C.,Riccardi,A.

fromgroundadaptivesecondaries

toaspaceactiveprimary

CGS S.p.A.: coordinator

ADS International: mech. System

MICROGATE: electr.+control systems+testing

CNR-INO Italian Optics Inst.: shell

INAF-Italian Astrophysics Inst.:

AO expertise+optical testing

ESA

INO

C.Vettore, F. Duo

D.Gallieni, M.Tintori, P.Lazzarini

R. Biasi, C.Patauner

F. D’Amato, M. Pucci

R. Briguglio, M. Xompero, A. Riccardi, F. Lisi’

L. Maresi, A. Zuccaro Marchi, J. Pereira do Carmo

TheLATTTeam

LATT?Conceptanddemonstrator

• Is our response totheneeds ofspacemirrors:• Largeformat• Possiblydeployable/segmented• Lightweighted• Activelyshaped

• Scientificcases• Astronomicaltelescope• LIDAR• Earthmonitoring• Telecommunications

Preliminarystudy:*ALCprojectin2007LATTprototyping:*ESTEC/ContractNo.22321/09/NL/RAExpertisefromLBT672,DSM,M4DP:Technologies,strategies,procedures

Actually our secretgoalwastofix theESAlogo!!!

LATTcanhandleit!

Projectstatus

• Endedinoctober2015withfinalreview@ESA-ESTEC:

• Lightweigth:betterthanJWST• Actuatorstroke>>competitors• Powerconsumption:almostnegligible• Concept:veryattractiveforfuturedevelopments

• PresentedatSpaceActiveOptics@ESTEC(nov.2015)

• Unique oflargeformat,deformable• Uniqueconceptaddressing segmentation• Unique applicable toprimary mirror concept

LATT:400mm,F/6sphere,19acts

• CFRP+AlhoneycombReferenceBody(<9 kg/m2)

• Co-located,contactless,position capacitivesensors (8 nmprecision)

• Contactless,voice-coilmotors (<55mW,1mmstroke,,± 0.24Nand0.08Nforflat)

• Lowprint-through gluedmagnet(19acts)

• Thinglassshell(400mmdiamx1mmth.,F/6)

• 1singlecable,1smallelectronicsbox(15W)(providing localcontrol loopandlaunchsafetymechanism forthethinshell)

400mm

Fromadaptivesecondariestoaspaceactiveprimary

LBT:ellipt.1m,672acts,kW,1kHzVLT:asph.1.2m,1170acts,kW,1kHz

LATT:spher.0.4m,19acts,1W,1Hz&newhaircap,tonsurton

?

Solutionsvalidated,towards TRL5

• Shellelectrostatic locking:Theshell is electrically ‘glued’ontheRefBodyduring launch

• Goaloptical quality

• Reduced power consumptionContactless,voice-coilmotors(<55mW,1mmstroke)Low bandwith smartactuators

Solutionsvalidated,towards TRL5

• Shellelectrostatic locking:Theshell is electrically ‘glued’ontheRefBodyduring launch

• Goaloptical quality

• Reduced power consumptionContactless,voice-coilmotors(<55mW,1mmstroke)Low bandwith smartactuators

Solutionsvalidated,towards TRL5

• Shellelectrostatic locking:Theshell is electrically ‘glued’ontheRefBodyduring launch

• Stability checked• Comparablewithground

based technology:flattened 30nmRMSWFE

• Goaloptical quality

• Reduced power consumptionContactless,voice-coilmotors(<55mW,1mmstroke)Low bandwith smartactuators

LATT- integration

Actuatorcupsmountedonthealuminumhoneycomb

Referencebodyfrontsurfacewithcapacitivesensor

Actuatormagnetsgluedontheshell Shellmountedonthereferencebody

Laboratorytestcampaign

12

Vibrationtest

ThermaltestThermo-vacuumtest

Electrostaticlockingtest

lockingpressure:600N/m2

Opticaltest

WFEcomparablewithAOafterremovingthemembranesdeformation(λ/6 @UV)

Maxacceler.:10g

Temperaturerange:-25°Cà55°CTested@1e-5mbar

13

• @sameopticalarea:• Largeractuatordensityisfeasible (nooptical

compression)• Lowerprint-through (dispersedonlargerarea)

• @sameactuatordensity:• Largercorrectionrange (lower localstiffness:pvs p’)• Lowerpower-budget (lowerlocalstiffness)

• Easiermanufacturing,nominiaturization

p

p’

LATTscaling:fromsecondary toprimary

14 ESTEC/ContractNo.22321/09/NL/RA

• 2in1:activeelement+lightweight<22kg/m2

• lowarealdensitycomparedtoexistingsystems• noneedtodevelopnovellightweighttechnologies• Norelay,noadditionaloptics,simpledesign

• Verylowpowerconsumption• <55mwforeachact• 15Wforcontrolelectronics

• Naturalsolutionforsegmentedmirrors• Alignment+phasingallocatedtoactiveoptics• Actstroke&accuracyrelaxdeploymenttolerances• Complexmirrortopology:localcorrectionis easier

WhyaLATT-likeprimarymirrorisattractive

Conclusion• Thinshell+voicecoilacts+capac.sensors:wellestablishedtechnologyforAOmirrors

• LATT:• Sphericalprimarymirror,40cm diam,F/6• 19acts,55mW/act• CFRP+ALhoneycomb+thinzerodurshell:<22kg/m2

• LATTdemonstrateditsapplicabilitytospace:• lightweightshell launchstresses• Lowpowerbudget shellcontrollability

• LATTdemonstratedtheconceptof:• Active+lightweight spaceprimary(2in1)• Suitabletosegmented/deployablesystems

LATTOBB:40cm,19acts

1m,7segments

1m,monolithic3-5m,segmented

LATT:abrickformorecomplexsystems