简介:Weproposeanovelsmall-anglemeasuringopticalmethodbasedontheastigmaticeffectoftwoorthogonallyplacedcylindricallenses.Accordingtotheone-to-onecorrespondencebetweenthelaserspotshapeandtheangle,theangleisdetermined.Wetheoreticallyanalyzethemeasuringrangeanddemonstratethatalongerdistancebetweentherotatingaxisandtheopticalaxisleadstoasmallermeasuringrange,butbettersensitivity.Also,anassociatedexperimentalsystemisestablishedandameasuringrangeof0.94mrad(cubicfitr=0.9993)aswellasagoodlinearrangeof0.37mrad(linearfitr=0.9994)witharesolutionof8μradisachieved.
简介:Anewapproachisproposedtoaccuratelydeterminethethicknessoffilms,especiallyforultra-thinfilms,throughspectrum-fittingwiththeassistanceofaninterferencelayer.Thedeterminationlimitcanreachevenlessthan1nm.Itsaccuracyisfarbetterthanthatofthetraditionalmethods.Thisdeterminationmethodisverifiedbyexperiments,andthedeterminationlimitisatleast3.5nmcomparedwiththeresultsofatomicforcemicroscope(AFM).Furthermore,adoubleinterference-aidedspectrafittingmethodisproposedtoreducetherequirementsofthedeterminationinstruments,whichthusallowsonetodeterminethefilm’sthicknesswithalow-precisioncommonspectrometerandtogreatlylowerthecost.Itisaveryhigh-precisiondeterminationmethodforon-siteandin-situapplications,especiallyforultra-thinfilms.
简介:为了精确地检测非旋转对称的非球面面形质量,将衍射补偿元件计算全息图(CGH)应用到非球面透射式检测光学系统中。利用计算全息图(CGH)可以生成任意形状的波前这一特点,对由三次面形和双曲面叠加而成的集成式波前编码器件进行检测,详细地给出了从检测系统的设计、计算全息图数学模型的建立,到CGH的制作和制作误差分析的过程。以口径33.84mm的波前编码器件为例,检测系统的模拟残余波像差的峰谷值是0.0373λ,均方根为0.0063λ。利用激光直写技术,加工制作了口径为56mm的计算全息板,计算全息图的制作误差为0.086λ,验证了计算全息图在检测自由曲面中的可行性。
简介:Twodifferentmethodsfromgraphicprocessingunit(GPU)andcentralprocessingunit(CPU)areproposedtosuitablyoptimizelook-uptablealgorithmsofcomputergeneratedholography(CGH).Thenumericalsimulationsandexperimentalresultsshowthatwecanreconstructagoodqualityobject.ThecomputationofCGHforathree-dimensional(3D)dynamicholographicdisplaycanalsobespedupbyprogrammingwithourproposedmethod.Itcanoptimizebothfileloadingandtheinlinecalculationprocess.Thephase-onlyCGHwithgigabytedataforreconstructing10MBobjectsamplingsisgenerated.Inaddition,theproposedmethodeffectivelyreducedtimecostsofloadingandwritingofflinetablesonaCPU.ItisbelievedtheproposedmethodcanprovidehighspeedandhugedataCGHfor3Ddynamicholographicdisplaysinthenearfuture.
简介:Amethodtothree-dimensionalpositionmovingparticleswithonelensandtwocamerasisproposed.Twoparticleimageswithdifferentdegreesofdefocusingareadoptedtosolvetheambiguousproblemofparticlepositions.Asingle-lensdual-camerasystemisdevelopedtosimultaneouslycapturethesetwoimagesforthemovingparticles.Themeasurementprinciplesandtheoreticalanalysisareintroducedfirst,andthensimulatedinvestigationsandexperimentalresearcharediscussed.Themeasurementerrorsinthesimulationsandexperimentsarelessthan1%and4%,respectively,in20timesthedepthoffieldofthesystem,whichvalidatesthefeasibilityofthismethod.
简介:利用单色平行光照射玻璃微珠,入射光在玻璃微珠内经过一次或多次内反射后出射光在最小偏向角会形成彩虹条纹。基于几何光学理论,根据最小偏向角的大小计算玻璃微珠的折射率。为了实现其快速测量,采用参数递推公式计算Otsu法的最佳阈值,并用改进的Otsu法对彩虹图进行了有效的阈值分割。提出了一种能快速有效判断彩虹条纹边缘的方法,并用该方法自动测量了彩虹条纹最外环边缘半径,从而实现了最小偏向角的快速计算。此外,对玻璃微珠折射率测量过程中的不确定度进行了计算,对不同型号的玻璃微珠,折射率的不确定度在10-4数量级,验证了上述方法的正确性。