简介:Thispaperpresentsalarge-scaleparticletrackingvelocimetry(LSPTV)systemformeasuringsurfacevelocityinvastunsteadyflows.Thesystemconsistsofaflexiblenumberofone-computer-six-cameraworkingunitsconnectedvialocalnetworkortheinternet.Multiplezero-tiltingcamerasareusedtoincreasesthefieldofviewwithminimumperspectivedistortions.Externalsynchronizationofvideooutputsofallcamerasfacilitatesuninterruptedimageacquisitionwithinthesystem.Effectivenessandefficiencyofthemulti-channelLSPTVareenhancedbyoptimizingillumination,flowseeding,imageacquisitionandcorrection,traceridentification,particlematching,andpost-processing.ThecapacityoftheLSPTVwasdemonstratedinthemeasurementofphysicalmodelflowsfortheThreeGorgesProject.
简介:Inordertoimprovetheresolutionofdigitalholographywithacommon-dimensioncharge-coupleddevice(CCD)sensor,thepointspreadfunctionsarebrieflyderivedforthecommonlyusedandpracticalpost-magnification,pre-magnification,andimage-planedigitalholographicmicroscopicsystems.Theultimateresolutionsofthesesystemsareanalyzedandcompared.Theresultsshowthattheultimatelateralresolutionofpre-magnificationdigitalholographyissuperiortothatofpost-magnificationdigitalholographyinthesameconditions.Wealsodemonstratethattheultimatelateralresolutionofimage-planedigitalholographyhasnocorrelationwiththephotosensitivedimensionoftheCCDsensor,anditisnotsignificantlyrelatedtothepixelsizeofthesensor.Moreover,boththeultimateresolutionandtheimagingqualityofimage-planedigitalholographyaresuperiortothatofpre-andpost-magnificationdigitalholographicmicroscopy.High-resolutionimaging,whoseresolutionisclosetotheultimateresolutionofthemicroscopeobjective,canbeachievedbyimage-planedigitalholographyevenwithasubmillimeter-dimensionsensor.Thissystem,bywhichperfectimagingcanbeachieved,isoptimalforcommonlyuseddigitalholographicmicroscopy.Experimentalresultsdemonstratethecorrectnessofthetheoreticalanalysis.
简介:摘要本文全面研究了三线阵CCD立体测绘相机的应用原理研制一种实践性强的测绘相机光机结构,其是将3部相机以不同的角度安装在测绘基座中。单相机以像方远心亚对称光学系统为基础,包括四个组件,即单镜安装在薄壁壳体的镜头、以凸轮导向结构为准的调焦机构、成像电器盒、基准镜。测绘基座属于此相机的一个重要支撑体,则是由7个筒单元、3个板单元和底座组合而成的。星敏支架是以星敏感器为基础,通过3个筒单元、1个圆锥单元组合而成。以PATRAN/NAS-TRAN软件为基础对测绘相机展开工程研究发现,其结合体的刚度与强度达标,遵循航天光学遥感器的标准规定。通过振动试验发现,对于测绘相机一阶固有频率来说,超过100HZ,无法和整星引起共振;利用在轨运行试验能够发现,测绘相机结构固定,符合相应的精度标准。
简介:AsoneofthekeyunitsofspaceCCDcamera,thetemperaturerangeandstabilityofCCDcomponentsaffecttheimage’sindexes.Reasonablethermaldesignandrobustthermalcontroldevicesareneeded.Onekindoftemperaturecontrolloopheatpipe(TCLHP)isdesigned,whichhighlymeetsthethermalcontrolrequirementsofCCDcomponents.InordertostudythedynamicbehaviorsofheatandmasstransferofTCLHP,particularlyintheorbitalflightcase,atransientnumericalmodelisdevelopedbyusingthewell-establishedempiricalcorrelationsforflowmodelswithinthreedimensionalthermalmodeling.Thetemperaturecontrolprincipleanddetailsofmathematicalmodelarepresented.Themodelisusedtostudyoperatingstate,flowandheatcharacteristicsbasedupontheanalysesofvariationsoftemperature,pressureandqualityunderdifferentoperatingmodesandexternalheatfluxvariations.TheresultsindicatethatTCLHPcansatisfythethermalcontrolrequirementsofCCDcomponentswell,andalwaysensuregoodtemperaturestabilityanduniformity.Bycomparisonbetweenflightdataandsimulatedresults,itisfoundthatthemodelistobeaccuratetowithin1℃.ThemodelcanbebetterusedforpredictingandunderstandingthetransientperformanceofTCLHP.
简介:Usingcomputer-controlledliquidcrystaldisplay(LCD)asanimageprocessorandaCCDcameraasadetector,phase-onlycorrelationmeasurementisperformedwiththeaidofjointtransformcorrelationmethod(JTC).Thiscomputer-controlledLCD-CCDimageprocessingsystemmaybeapowerfultoolfordefectdetection,positioncontrolandpatternrecognition.Itenablesnewpossibilitiesinanalogreal-timeimageprocessing.Thisisofgreatinterestinmicroelectronicmanufacturingtodayandinthefuture.
简介:根据氨基甲酸酯类农药在紫外光的照射下能够发出荧光的机理,设计了一种基于电荷耦合器件(CCD)的检测该类有机农药残留的光纤荧光测量系统。该系统以脉冲氙灯为激发光源,利用光纤探测和传输荧光,采用线阵CCD代替传统的光电倍增管作为荧光信号的光电检测元件,同时配备A/D高速数据采集卡,实现了单片机控制下荧光信号的光电转换以及数据采集,进而实现了对西维因和克百威农药浓度的测量。实验结果表明,在激发波长分别为280nm和285nm时,西维因和克百威的荧光强度分别在330nm和315nm处达到最大,最低检出限分别为3.7ug/L和6.5ug/L。在5~1000ug/L范围内,荧光强度和溶液浓度基本呈线性关系。该测量系统灵敏度高,线性范围宽,可以满足荧光检测的要求。