吳楨等:長基線恒星光干涉技術中延遲線系統的設計與實驗中國科學:物理學力學天文學2012年第42卷第2期圖7實驗系統示意圖Figure7Schematicdiagramofexperimentalsystem.本預計采用裝調好后的系統(如圖6)進行實驗;實驗發現從雙頻激光干涉儀出來的光束經拋物面反射鏡反射后其偏振特性被改變,雙頻激光干涉儀無法探測到,因此我們只好將雙頻激光干涉儀自帶的平面反射鏡直接安裝在PZT系統上(如圖7),但是工作原理是一樣的.采用這樣的實驗系統,我們首先測試了精密運動平臺的跟蹤誤差.只有精密運動平臺更新運動速度、PZT不動的情況下,測試結果如圖4,表明精密運動平臺的跟蹤誤差為5m.假設觀測中心波長為500nm,帶寬為5nm,為了使條紋可見度的損失小于1%,延遲補償的精度應好于相干長度的十分之一,則光程差應該維持在±3m內.小車的跟蹤速度每秒鐘更新一次,PZT系統補償頻率每秒鐘40次對上述的運動曲線進行跟蹤.圖8為最終的跟蹤誤差,從圖8中可以看出,除了個別點的跟蹤誤差比較大(三角所示,大約為1m),整個系統的跟蹤精度是非常高的.這樣的跟蹤精度滿足±3m的要求.5結論通過實驗,在PZT校正頻率為40Hz時,其跟蹤誤差在短時間內基本處于±1m以內,滿足了實際觀測的要求.由于軟件采用動態鏈接庫方式獲取數據,圖8系統跟蹤誤差(單位:counts,1counts為50nm)Figure8Trackingerrorofthesystem(unit:counts,1countsis50nm).并通過網絡方式進行數據傳輸,經過測試,網絡傳輸的時延會到達10ms以上,動態鏈接庫獲取位置數據的程序段,執行時間也在幾個ms級,因此限制了整個控制系統的帶寬,無法再大幅度提高控制頻率,因此在現有的軟實時控制模式下要進一步提高跟蹤精度,難度很大.國外已經建成的干涉儀延遲線控制系統都是基于硬實時來實現的,控制頻率幾千Hz.延遲線要達到理想控制目標,應該考慮硬實時的方法.本課題的研究表明我們采用的二級補償系統是可行的,下一步我們將繼續提高精密運動平臺的跟蹤精度以及運動的穩定性;改變控制系統,采用硬件實時控制.參考文獻王正明,徐家巖,蕭金宏,等.天文光干涉測量.北京:科學出版社,1996LawsonPR,ThompsonBJ.SelectedPapersonLongBaselineStellarInterferometry.Bellingham,WA:SPIEOpticalEngineeringPress,1997GarciaPJV,HenningT,GlindemannA.TheveryLargeTelescopeInterferometer––ChallengesfortheFuture.Dordrecht:Springer,2007LawsonPR.Principlesoflongbaselinestellarinterferometry.CourseNotesfromthe1999MichelsonSummerSchool.Pasadena:NationalAeronauticsandSpaceAdministration,JetPropulsionLaboratory,CaliforniaInstituteofTechnology,1999MonnierJD.Opticalinterferometryinastronomy.RepProgPhys,2003,66:789–857JankovS.Astronomicalopticalinterferometry1.MethodsandInstrumentation.SerbAstronJ,2010,181:1–17MartinC.RecentastrophysicalresultsfromtheVLTI.Messenger,2005,121:52–55LawsonPR.Advancesinsciencewithstellarinterferometers2004–2006.ProcSPIE,2006:626801MonnierJD,ZhaoM,PedrettiE,etal.Imagingthesurfaceofaltair.Science,2007,317(5836):342–345ZhaoM,GiesD,MonnierJD,etal.FirstresolvedimagesoftheeclipsingandinteractingBinarybLyrae.AstrophysJ,2008,684:L95–L98YoungJS,BaldwinJE,BasdenAG,etal.AstrophysicalresultsfromCOAST.ProcSPIE,2001,4838:369–378Karovska

M.Interferometricsurveysandresultsonvariablestars:Nowandinthefuture.JAmAssocVariableStarObs,2006,35(1):34–42LaneBF,MuterspaughMW.Differentialastrometryofsubarcsecondscalebinariesatthepalomartestbedinterferometer.AstrophysJ,2004,601:1129–1135BainesEK,McAlisterHA,TenBrummelaarTA,etal.\o"|Subgiantstars|Astrophysicalresults|CHARA|Giantstars|Dwarfstars|CHARAClassic|NearInfrared|"ElevenexoplanethoststarangulardiametersfromtheCHARAarray.AstrophysJ,2009,701(1):154–162DavisJ,JacobAP,RobertsonJG,etal.\o"|Cepheidvariables|SUSI|Astrophysicalresults|Visibledomain|"ObservationsofthepulsationoftheCepheidlCarwiththeSydneyUniversityStellarInterferometer.MonNotRAstronSoc,2009,394(3):1620–1630KishimotoM,H?nigSF,AntonucciR,etal.\o"|ActiveGalacticNuclei|Keck|Astrophysicalresults|NearInfrared|"Exploringtheinnerregionoftype1AGNswiththeKeckinterferometer.AstronAstrophys,2009,507(3):L57–L60DavisJ,TangoWJ,BoothAJ,etal.TheSydneyUniversityStellarInterferometer-ⅠTheinstrument.MonNotRAstronSoc,1999,303:773–782ArmstrongJT,MozurkewichD,JrickardL,etal.Thenavyprototypeopticalinterferometer.AstrophysJ,1998,496:550–571ShaoM,ColavitaMM,HinesBE,etal.ThemarkⅢstellarinterferometer.AstronAstrophys,1988,193:357–371ColavitaMM,WallaceJK,HinesBE,etal.Thepalomartestbedinterferometer.AstrophysJ,1999,510:505–521McAlisterHA,BagnuoloWG,BrummelaarTA,etal.TheCHARAarrayonMountWilson.ProcSPIE,2000,4006:465–471ColavitaMM,WizinowichPL.KeckInterferometerupdate.ProcSPIE,2003,4838:79–88吳楨.基于光干涉技術的高精度高分辨率成像.10000個科學難題·天文卷.北京:科學出版社,2010.955–959duForestoVC.Groundandspacebasedinterferometry.BullSocRSciLiege,2005,74:357–358DerieF.VLTIdelaylines:Design,developmentandperformancerequirements.ProcSPIE,2000,4006:25–30HogenhuisH,VisserM,DerieF.CommissioningoftheVLTIdelaylinesonmountparanal.ProcSPIE,2003,4838:1148–1154李超.邁克爾遜式恒星干涉儀延遲線試驗平臺控制系統設計與實現.碩士學位論文.北京:中國科學院研究生院,2010

Designandexperimentofthedelaylinesystemforlongbaselinestellarinterferometry?WUZhen1,2*,LIChao1,2,3,LINXieJia1,2,3,ChenYi1,2&WANGJiaNing1,21NanjingInstituteofAstronomicalOptics&Technology,NationalAstronomicalObservatories,ChineseAcademyofSciences,Nanjing210042,China;

2KeylaboratoryofCASforAstronomicalopticsandtechnology,ChineseAcademyofSciences,Nanjing210042,China;

3GraduateUniversityofChineseAcademyofSciences,Beijing100049,ChinaOpticaldelaylinesystemusedtocompensatethegeometricopticalpathdifferenceisoneofkeysubsystemofthelongbaselinestellarinterferometer.AtwostagescompensationdelaylinesystemdevelopedbyNanjingIns