TCS-Aberra*on Control: status and perspec*ves
V.Fafone
24/07/2018 1
Outline
• AdVTCSoverview;• TCSperformancesinAdV:
• In-situabsorpEonmeasurementwithHWS(@13Winputpower);
• ITFinputpowerincreasefrom14Wto26.5W;
• DoubleAxiconSystemtests;
• Lessonslearnedforfutureupgrades:
• AdV+
224/07/2018
AdV TCS overview
24/07/2018 3
• HWS-RC(onINJandDETbenches)tomeasurethermaldistorEonsinrecyclingcavity;
• HWS-HR(4)tomeasurechangeinTMRoCs;
• RHs,tocontrolthearmcavitymirrorsRoCs(andPRaswell…);
• CO2projectors:correctopEcalaberraEons(coldandthermal)intherecyclingcavity.
AdV TCS overview
24/07/2018 4
• HWS-RC(onINJandDETbenches)tomeasurethermaldistorEonsinrecyclingcavity;
• HWS-HR(4)tomeasurechangeinTMRoCs;
• RHs,tocontrolthearmcavitymirrorsRoCs(andPRaswell…);
• CO2projectors:correctopEcalaberraEons(coldandthermal)intherecyclingcavity.
AdV TCS overview
24/07/2018 5
• HWS-RC(onINJandDETbenches)tomeasurethermaldistorEonsinrecyclingcavity;
• HWS-HR(4)tomeasurechangeinTMRoCs;
• RHs,tocontrolthearmcavitymirrorsRoCs(andPRaswell…);
• CO2projectors:correctopEcalaberraEons(coldandthermal)intherecyclingcavity.
AdV TCS overview
24/07/2018 6
• HWS-RC(onINJandDETbenches)tomeasurethermaldistorEonsinrecyclingcavity;
• HWS-HR(4)tomeasurechangeinTMRoCs;
• RHs,tocontrolthearmcavitymirrorsRoCs(andPRaswell…);
• CO2projectors:correctopEcalaberraEons(coldandthermal)intherecyclingcavity.
AdV TCS overview
24/07/2018 7
• HWS-RC(onINJandDETbenches)tomeasurethermaldistorEonsinrecyclingcavity;
• HWS-HR(4)tomeasurechangeinTMRoCs;
• RHs,tocontrolthearmcavitymirrorsRoCs(andPRaswell…);
• CO2projectors:correctopEcalaberraEons(coldandthermal)intherecyclingcavity.
HWS-INJ
HWS-DET
HWS-RC
24/07/2018 8
} On-axisdoublepassmeasurementinreflecEonwithauxiliarydedicatedbeamsoneachITM+CPpairs;
} HWSopEcsinstalledonEIBandEDB:◦ ExploitmagnificaEonofinjecEonanddetecEonMMTs;
} POPandBSalsosensed(allPRcavityopEcsopEmizedincollaboraEonwithLMAforHWSsensingbeamssincetheTCSdesignphase);
} INJandDETHWSbeamsatthesamewavelength:cross-samplingavoidedbycustomBSHRcoaEng(>98%R@790nm)thankstointeracEonwithLMA;
Fromsource
BacktoHartmannsensor
OpEcundertest
WITM absorp*on measurement
24/07/2018 9
• HWS-INJdatacollectedduringtheshortTCScommissioningphasebeforeO2(on28/03/2017at18:14UTCfor5hours);
• WemeasurethethermallensinducedbytheYAGwhosemaincontributoristheabsorpEonintheHRcoaEng
• EsEmatedcoaEngabsorpEon:(0.28±0.06)ppm
• LMAmeasurement(VIR-0543A-14)is:(0.22±0.06)ppm
} WavefrontreconstrucEonsolwaredevelopedincollaboraEonwithAdelaideUniv;} Pre-installaEontestsatRomeTorVergataUniversity.FirstcharacterizaEononAdVdoneduringMSinstallaEon(March2018);
HWS-HR
24/07/2018 10In-vacuumretro-reflector
Fromsource
BacktoHartmannsensor
} Off-axisdoublepassmeasurementinreflecEonwithauxiliarydedicatedbeamsoneachTM–uniquefeatureofVirgo;
} HWSopEcsinstalledondedicatedbenches;} In-vacuumopEcsrequiredforbeamsteeringandback-reflecEon;} SameHWSsensorsasforrecyclingcaviEes;} SensesthechangeofRoCduetoabsorpEonswithasensingbeamabout15cmindiameterontheTMs;
RHs
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} ControlRoCsofalltestmassesandPRmirror;} FortheITMs,providelimitedcompensaEonofthermallensing;} CanbeusedtomiEgateparametricinstabiliEes:tuningtheRoCmovestheresonantfrequencyofhigherordermodes;
} ProvidealmostsphericallensandidenEfyITMscentersinHWSimages;
RHs
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} Comparisonwithexpectedbehaviorshowsverygoodagreementàthesystemiswellunderstoodandwellbehaving;
CO2 projectors
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} ThreeactuaEonlines:◦ DoubleAxiconSystem(DAS):correctforthermallensingoraxisymmetricaberraEons;◦ CentralHeaEng(CH):addforthermallensing,opEmizecontrastdefect;◦ ScanningSystem(SS):correctfornon-uniformaberraEons;
ITF input power increase
24/07/2018 14
• SidebandsrecyclinggainmeasuredatdifferentITFinputpowerswithnothermalcompensaEon;
• TwosetsofopEcalsimulaEonscarriedonusingabsorpEonsmeasurementsdone:• atLMAbeforeinstallaEon.SeeVIR-0543A-14:0.22ppm
forWIandVIR-0544A-14:0.19ppmforNI;• onsitewiththeHWSontheWestITM(VIR-0244A-17):
0.28ppm;NorthITMabsorpEonslelattheLMAvalue.• On-sitemeasurementofNIabsorpEonneedstobeperformed;• ComparisonwithsimulaEonswillberepeatedaler
measurementofNIabsorpEon.
PITF[W] SimulatedGsid MeasuredGsid ΔG/G
14 12 11.35+/-0.07 6%
17 11.4 10.83+/-0.04 5%
20 10.8 9.73+/-0.03 10%
26.5 8.8 8.90+/-0.04 2%
ComparisonofmeasurementsandsimulaEons
Double Axicon System tests: November 2017 • 14WITF:accordingtosimulaEons,correcEonofthermallens
withDASmakestherecyclinggaintodecreaseàconfirmedbymeasurements;
• 25WITF:DASrequiredtocorrectlensinordertoimproverecyclinggainàconfirmedbymeasurements;
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P=14W
P=17W
P=20W
P=26.5W
P=26.5WDASON
Summary of the first commissioning rounds • AllTCScomponentstestedandworkingasperspecificaEons;• FirstcommissioningtestsdonelastNovember:
• resultsseemtogointherightdirecEon:• recyclingcavitygainimprovedwithDASON• RCgainwasbeqerwithadifferenEalpowerapplied(asexpectedfromsimulaEons)• alsoITFstabilityappearedposiEvelyinfluencedbytheDASacEon
• comparisonofthemeasuredandsimulated56MHzrecgainreasonablygood
• PathtomaketheITFwork@25Wseemstobeunderstood,noshowstopperduetoaberraEonsfound
• ….Then….• ITFsensiEvity• Etalon• Parametricinstabili?es• …..
• TCScanhelpimprovingthings24/07/2018 16
Lessons and requirements for AdV+
24/07/2018 17
} CorrecEonofwavefrontaberraEons:◦ CO2lasersextensivelyusedsofar:
� SiO2absorbsallradiaEonatλ>5µm;◦ AdV+withincreasedbeamsizeinrecyclingcavitymoresensiEvetoaberraEonsthanAdV;◦ QualityofcompensaEonreliesoncapabilityofproducingtheopEmalheaEngpaqern:� Inthefuturetherewillbeanincreasedneedfornon-symmetricheaEngpaqerns;� Preciselaserbeamshapingrequiresgoodqualitylaseroutputbeam:
� SpaEalbeamfilterinstalledonAdVCO2benches;� OngoingacEvitytobuildamodecleaneratUToV.
Op*mal hea*ng paSern
Lessons and requirements for AdV+
24/07/2018 18
• Laserbasedtechniques:• Scanningsystem–installedinAdV;• InjectsdisplacementnoiseintotheITF:
• Peakduetothermo-refracEvecouplingatthescanningrepeEEonfrequency(andharmonics);
• ComboflinesduetotorqueappliedonCP(radiaEonpressure);
• DevelopmentofDCactuatormandatory;• MEMSdeformablemirrors–underinvesEgaEonatUToV;
• LargeareahighsensiEvityCCDrequired(pyroelectricsensorarray).
R.Lawrence
The simula*on is obtained for flat incident intensity on an array of 40x40 micromirrors with 1 mm side M. Lorenzini
Lessons and requirements for AdV+
24/07/2018 19
• NotmuchtocomplainabouttheHWS:• Noisefloorandaccuracyareverygood.
• However…thereisroomforimprovement:• Thesensorisaffectedbyroomtemperaturechanges;• More,achangeintemperaturewillalsomodifythedistancebetweentheopEcsoftheimagingtelescope,inducingafakecurvature(thermalde-focus);
A.Brooks
MeasuredinVirgo
x10-10mMeasuredintheTorVergatatestfacility(TETIS)
Lessons and requirements for AdV+
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• KnownsoluEons:• TemperaturestabilizaEonoftheHWS–doneatUToV;• Twocolorsystem:anaddiEonalbeam(atadifferentλwrttothesensingbeam)thatmeasuresthethermalde-focusàmayworkfineinthelab,maybelesspracEcalonAdV+(requiresspecialcoaEngsoncoreopEcs…);
L.Aiello
• SpaEalresoluEon:• Atpresent,areaonTMprobedisabout200mmindiameter;• ConsideringthetelescopemagnificaEonanddistance
betweentheholesàresoluEonabout7mm;• AdV+implieslargerbeamsize,resoluEonwilldegrade;
• ThepresentlyusedCCDisnolongerbeingproducedàimpliesare-designandopEmizaEonoftheHP;
• RequestconcernsasetupforCCDcandidatecharacterizaEon.
Lessons and requirements for AdV+
24/07/2018 21Credits: J. Degallaix
• AdV+:• ThermalnoisereducEon;• IncreasesizeoftestmassesandbeamdimensionsonTMs;• ArmcaviEesclosertoinstability;
Lessons and requirements for AdV+
24/07/2018 22Credits: J. Degallaix
• AdV+:• ThermalnoisereducEon;• IncreasesizeoftestmassesandbeamdimensionsonTMs;• ArmcaviEesclosertoinstability;
Lessons and requirements for AdV+
24/07/2018 23
• AdV+:• ThermalnoisereducEon;• IncreasesizeoftestmassesandbeamdimensionsonTMs;• ArmcaviEesclosertoinstability;
MoresensiEvetoopEcalaberraEons
Lessons and requirements for AdV+
24/07/2018 24
• AdV+:• ThermalnoisereducEon;• IncreasesizeoftestmassesandbeamdimensionsonTMs;• ArmcaviEesclosertoinstability;
Richieste
24/07/2018 25
• LerichiestefinanziarievannosoqoAdV+(tag:AdV+LM-TCS)
• Richieste:61.5kEuro• CO2:46kEuro• RH:8kEuro• HWS:8kEuro