Defendant's Motion to Strike Complaint for Unlawful Detainer
Answer – Unlawful Detainer - Welcome : Stanislaus County
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Pg. 1 Introduction: The technology of Spatial Light Modulators (SLM) grew from the need to quickly convert data in electronic form into spatially modulated coherent optical signals. This allows for the ability to introduce information into an optical system, since the information can be carried directly by the optical amplitude. To achieve this, one needs to manipulate the complex optical fields transmitted through the optical system. Originally photographic films were used for wavefront modulation but much more powerful optical information processing systems can be realized if the film is replaced by a spatial light modulator capable of changing transited light in real time in response to optical or electronic control signals (Goodman). Over the history of optical information processing, a great many different SLM technologies have emerged along with the proliferation of practical application. Such SLMs technologies include: Liquid Crystal SLMs, magneto‐optic SLMs, deformable mirror SLMs, and multiple‐quantum‐well (MQW) SLMs. Liquid Crystal SLMs are the most present in everyday technology and will be the type you will have the opportunity to work with. (Goodman). In this lab you will be investigating the properties and capabilities of a twisted-nematic liquid crystal SLM. The SLM is composed of carefully chosen dimensions of spatially separated liquid crystal cells. Liquid Crystals are considered a phase of matter in which the molecule order is between the crystalline solid state and the liquid state. Each LC cell is composed of long, cigar‐shaped molecules sandwiched between two alignment layers, which set the angle of the molecule’s long axis alignment at the interface. The two layers, however, do not share the same angle so the molecules form a “helix” structure as they traverse the cell, thus giving rise to a twisted appearance–See figure 1 (much like putting a deck of cards between your two hands and fanning it around–Hecht pg. 372). Nematic liquid crystals are ones where the molecules tend to be parallel but their position is randomly distributed across the cell. A wonderful set of pictures that do a much greater justice at conveying what a TN‐LCD is can be found in Hecht on pages 370‐373. The helix structure of the twisted nematic crystal can be used to change the polarization status of incident light. When the polarization of the light is parallel to the molecules of the cell at the entrance facet, the polarization follows the twist of the molecule axis. You can think of the cell as being a series of thin wave‐plates each with a minute gradation of their optical axis. Therefore the light leaves the cell with a polarization that is perpendicular to the incident polarization. In order to realize a dynamic optical element, a voltage is applied to the LC cell. This voltage causes changes of the
Transcript of Answer – Unlawful Detainer - Welcome : Stanislaus County
Pg.1
Introduction: ThetechnologyofSpatialLightModulators(SLM)grewfromtheneedtoquicklyconvertdatainelectronicformintospatiallymodulatedcoherentopticalsignals.Thisallowsfortheabilitytointroduceinformationintoanopticalsystem,sincetheinformationcanbecarrieddirectlybytheopticalamplitude.Toachievethis,oneneedstomanipulatethecomplexopticalfieldstransmittedthroughtheopticalsystem.Originallyphotographicfilmswereusedforwavefrontmodulationbutmuchmorepowerfulopticalinformationprocessingsystemscanberealizedifthefilmisreplacedbyaspatiallightmodulatorcapableofchangingtransitedlightinrealtimeinresponsetoopticalorelectroniccontrolsignals(Goodman). Overthehistoryofopticalinformationprocessing,agreatmanydifferentSLMtechnologieshaveemergedalongwiththeproliferationofpracticalapplication.SuchSLMstechnologiesinclude:LiquidCrystalSLMs,magneto‐opticSLMs,deformablemirrorSLMs,andmultiple‐quantum‐well(MQW)SLMs.LiquidCrystalSLMsarethemostpresentineverydaytechnologyandwillbethetypeyouwillhavetheopportunitytoworkwith.(Goodman). InthislabyouwillbeinvestigatingthepropertiesandcapabilitiesofatwistednematicliquidcrystalSLM.TheSLMiscomposedofcarefullychosendimensionsofspatiallyseparatedliquidcrystalcells.LiquidCrystalsareconsideredaphaseofmatterinwhichthemoleculeorderisbetweenthecrystallinesolidstateandtheliquidstate.EachLCcelliscomposedoflong,cigar‐shapedmoleculessandwichedbetweentwoalignmentlayers,whichsettheangleofthemolecule’slongaxisalignmentattheinterface.Thetwolayers,however,donotsharethesameanglesothemoleculesforma“helix”structureastheytraversethecell,thusgivingrisetoatwistedappearance–Seefigure1(muchlikeputtingadeckofcardsbetweenyourtwohandsandfanningitaround–Hechtpg.372).Nematicliquidcrystalsareoneswherethemoleculestendtobeparallelbuttheirpositionisrandomlydistributedacrossthecell.AwonderfulsetofpicturesthatdoamuchgreaterjusticeatconveyingwhataTN‐LCDiscanbefoundinHechtonpages370‐373.
Thehelixstructureofthetwistednematiccrystalcanbeusedtochangethepolarizationstatusofincidentlight.Whenthepolarizationofthelightisparalleltothemoleculesofthecellattheentrancefacet,thepolarizationfollowsthetwistofthemoleculeaxis.Youcanthinkofthecellasbeingaseriesofthinwave‐plateseachwithaminutegradationoftheiropticalaxis.Thereforethelightleavesthecellwithapolarizationthatisperpendiculartotheincidentpolarization.Inordertorealizeadynamicopticalelement,avoltageisappliedtotheLCcell.Thisvoltagecauseschangesofthe
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Figure1:Twisted‐nematicliquidcrystalcell
molecularorientation,asisillustratedinfigure2forthreevoltagesVA,VB,Vc.Additionallytothetwistcausedbythealignmentlayers,themoleculesexperienceavoltage‐dependenttiltifthevoltageishigherthanacertainthresholdvoltage.Withincreasingvoltage,onlysomemoleculesclosetothecellsurfacearestillinfluencedbythealignmentlayers,butthemajorityofmoleculesinthecenterofthecellwillbetalignedparalleltotheelectricfielddirection.
Figure2.
Theliquidcrystalisbirefringentandthuscanbedefinedbytwoindicesofrefractionsimilartoawaveplate.TheuniquefeatureabouttheliquidcrystaldisplayintheSLMistheextraordinaryrefractiveindexisdependantontheanglethemoleculesmakewiththenormaloftheentranceandexitlayer,typicallydefinedasthez‐axisordirectionofpropagation.Theexplicitformulaisgivenby
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sin2(θ)neo2 Eq.1
Theangleθisafunctionoftheappliedvoltage,sothevalueofneoisalsodependantonvoltage.Asθ→0wecanseethevalueofneo→noandtheliquidcrystalbecomesisotropici.e.theopticalpropertiesofthematerialarethesameinalldirections.Hence,lightpassingthroughwillonlyexperienceonerefractiveindex.ThisideaisofimportancetounderstandinghowthepolarizationoflightischangedbytheSLM.
Thefollowingisashortlistofaccessibletexts,withgermanechaptersindicated,whichyoushouldreferencetoyourassimilationofsomeofthemoredifficultconcepts.FurtherReadings:DiffractionandFourierOptics:
1) HechtCh7.3‐7.4.4,Ch10‐11,Ch13.2‐13.2.32) FowlesCh53) IntroductiontoFourierOpticsCh2‐44) Pedrotti’sInro.ToOpticsCh11,13,21
SpatialLightModulators:1) Intro.ToFourierOpticsCh7.22) HechtCh8.123) Pedrotti’sIntro.ToOpticsCh17‐54) OptiXplorerManual
*Additionallyitwouldbebeneficialtoreviewpolarization,interferenceandsomegeometricalopticssuchasmicroscopes.Section1:AmplitudemodulationandprojectionObjectives:TounderstandthefollowingexperimentsandthefunctionalityoftheLCdisplay,thepolarizationofthelightplaysacrucialrole.ThereforethepolarizationcharacteristicsoftheLCdisplaywillbedeterminedfirst.Thenaprojectorsetupwillbeassembledusingthelightmodulatorastheimagesource.Duringtheexperimentcontrastandpixelsizewillbedetermined.
MeasurementofthepolarizationpropertiesoftheSLM.
Inthisexperiment,thepolarizationpropertiesofthelightmodulatorwillbedetermined.PlacetheunaddressedLCdisplaybetweentwopolarizers,oralternativelyalinearlypolarizedlightsourceandapolarizer.Thetwopolarizers
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eachhaveapolarizationaxis,whichare[notindicatedonthepolarizer.Usingapolarizerwithaknownfixedaxisandthepower‐meter,determinethepolarizationaxisofthetwovariablepolarizers.Markthepolarizationanglewithasmallpieceoftape.]indicatedbythesmallmarkontheoutsideedgeoftheinnermount.Alignthismarkwiththe0degreemark.NextensurethatthebeamincidentontotheLCdisplayisbothcollimatedandcompletelyilluminatingthedisplay.Thisisdoneusing,whatiscommonlyreferredtoas,acagesystem,whichconsistsoftwolensesoffocallengthsf=30mmandf=200mmattachedtoarailguide.Adjustthelensseparationinorderexpandandcollimatethebeam.Usingthesecondpolarizerasananalyzer,measuretheangulardistributionoftheintensitybysettingthepolarizeratzerodegreesandvaryingtheanalyzerangle;10‐degreeincrementswillsuffice.Recordthedataandgraphnormalizedintensityvs.analyzerangle.WithoutremovingtheSLM,commentontheintensitycurveproducediftheSLMwereremovedfromthesetup.
Q1)IsthelightleavingtheSLMlinear,ellipticalorcircularpolarized?Howcanyoutell?
ProjectorSetup
UsingaLED/Whitelightsource,placeanf=75mmlensinsuchawaythatthebeamiscollimatedandlargeenoughtoilluminatetheentireLCdisplay.Makesurethatnoscatteredlightbypassesthedisplayusingarectangularaperture,whichcanbeconstructedfromapieceofcardboard.Placethepolarizer,analyzerandSLMbehindthecollimatinglenssimilartofigure1.TheSLMispositionedasclosetothecollimatinglensaspossible,sothattheapertureofthedisplayisfullyilluminated.Placeanobjectivelens(f=100mm)behindthedisplayandadjustitinsuchawaythatafocusedandenlargedimageappearsonthescreen.Tryusinganirisdiaphragmwithdifferentapertures.Q2)Whatistheinfluenceoftheapertureregardingthedepthoffocus,brightness,andinfluenceoflensaberrations.
AlllensesusedarePlano‐convex/concave.Indicatewhichsideshouldface
thelightsourceinordertoreduceaberrationandthenimplementyourdecisioninordertooptimizeyourprojector.
Pg.5
Figure3:Anexampleforaprojectorsetupwiththeopticalpathforillumination(black)and
theopticalpathforimaging(red)
OpentheOptiXplorersoftwarebygoingtoStart→AllPrograms→HoloeyeApp.Software2.8fortheOptiXplorer(x2).ThewindowthatwillopenshouldsayOptiXplorer2.8intheupper,leftcorner.Ifthisisnotthecaseortheprogramwillnotopen,re‐readtheinstructions,tryagainandifthereisstillaproblem,askforassistance.
UsetheOptiXplorersoftwaretoaddresstheSLMwithawhitescreenbyclickingonElementaryOpticalFunctions→ShowBlankScreen.Ahomogeneousgraylevelscreenshouldappear.Enlargetheblankscreensothatitfillstheentirecomputerdisplay.Positionthemousepointerontherightedgeofthewindowuntilatoolbarappears.Familiarizeyourselfwiththenameofeachbuttoninthetoolbaranditscorrespondingfunction;playaroundwiththesoftwareforafewminutes.
Onceyouarecomfortablewiththenamesandgeneralfunctionsofthe
toolbaradjustthegrayvalueoftheblankscreenuntilitisentirelywhite.Pressthe“Inverting”buttontotogglebetweenwhiteandblack.Next,rotatethepolarizers,whichareperpendiculartoeachother,inadequatestepsizes—10degreesworksfine—andmeasurethechangingcontrastquantitatively.Remembercontrastisgivenby,
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Imax − IminImax + Imin
Eq.2
whereImaxandImincorrespondtothewhiteandblackaddressedscreenrespectively.Findandrecordwhatpolarizer/analyzercombinationachievedthemaximumcontrast.Againbyclicking“ElementaryOpticalFunctions”scrolldownto“CircularAperture”andaddressacircleofreasonableradiusontotheSLM.Notewhathappenswhenoneorbothpolarizersareremoved.Keepthefirstpolarizersfixedattheoptimizedpositionandrotateonlythesecondone.Q3)Whatdoyouobserveintermsofcontrastwhenyourotatethesecondpolarizerby45/90/180degrees?
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PixelsizeoftheLCdisplay AddresstheLCdisplaywitharectangularobjectofknowndimensions.Usingtheprojectorsetupfromthepreviousexperiment,findthepixelsizeoftheLCdisplay;includeerror.Relationbetweenpixelvoltageandmodificationofthepolarizationstate
EverygraylevelcorrespondstoaspecificvoltageasingleLCDelementisaddressedwith.Thedifferentvoltageleadstoadifferenttiltintheliquidcrystalmoleculesandthereforeadifferentpolarizationstate.Determineforsixgraylevels(250,200,…0)therotationangleoftheanalyzerforthesmallestandlargestmeasuredpowervalues.
Thestateofpolarizationcanalwaysbedefinedasanellipse.Inparametricform,thesemi‐majoraxisacorrespondstomaximumpower,andaccordinglythesemi‐minoraxisbtotheminimumpower(measuredwiththeanalyzerrotated90degreestothemaximum).Theangleoftheanalyzerforthemaximumpowercorrespondstotheangle∆,whichdenotestherotationofthesemi‐majoraxistothex‐axis.
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Usingyourfavoriteormostreadilyavailablegraphingsoftware(Kaleidagraph),plotthesixdifferentellipsesforeachgrayvalue.Theresultsshouldbesimilartofigure4.
Figure4:Rotatedpolarizationellipsesfordifferentgreylevels(GL’s)
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Section2:LinearandseparablebinarybeamslittergratingsObjectives:
Illuminatingaspatiallightmodulatorwithacoherentlightsourcegeneratesdiffractionpatternsbehindthedisplaysimilartothosethatappearbehindaconventionalopticalgrating.Onecanconsiderthenon‐addresseddisplayasanopticalgrating.Thereasonforthisliesinthestructureofasinglepixel.Itconsistsofthetransparentpartoftheliquidcrystalcellandthenon‐transparentpartofthecontrolelectronics.Assumingzerotransmissionforthispartofthecell,thedisplaycanbeseenasatwo‐dimensionalseparablegratingwithastructureasshowninFig.5.Withaso‐called“FourierLens”thediffractionpatternallowsconclusionstobedrawnaboutthecharacteristicsofthedisplay.
Figure5:Simplifiedmodelofapixelwithitstransmission
Generationofdiffractionpattern
CollimateandexpandthelaserbeamsotheentireLCdisplayisilluminated.Placealens(f=250mm)infrontoftheSLMsuchthatthepositionoftheSLMandthefrontfocallengthofthelenscoincide.Movetheprojectorscreenintherearfocalplaneofthelens.Youshouldseeafocusedarrayofbrightspots. Duetotheapertureofthelens,thelightthatcancontributetothediffractionpatternisrestricted.Thatmeans,foraparticulardiffractionorder,onlypartial
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wavesfromacertainpartoftheilluminatedareaonthemodulatorcancontribute.Placingthemodulatordirectlyinfrontofthelensminimizesthiseffect.Ifthescreenisnotpositionedintherearfocalplaneofthelens,thesizeofthediffractionpatterndependsonthepositionofthelightmodulator.TryplacingthelensbehindtheSLM.ObservewhathappenswhentheSLM’spositionisvariedwithinthelens’srearfocallength.YoushouldnotethelensstillactsaFourierTransform,whichgeneratesafar‐fielddiffractionpatternatthelens’sfocalplane!
Figure6:AFourierlensgeneratesthefarfielddiffractionpatterninitsrearfocalplane
Adjustthesetupsoyoucanclearlyseethearrayofbrightspots.Youmayneedtoplaceadiverginglensbehindthesetupsothediffractionpatternisenlargedforbettermeasurements.Recallthepixelarraycanbethoughtofasatwo‐dimensionalgratingabletobeseparatedintotwoperpendicularN‐slitgratings.WiththisandFig.5inmind,determinetheslitwidthandseparationforaN‐slitgratinginthehorizontaldirection.Repeatthisprocedurealongtheverticaldirection.Q4)Fromyoumeasurements,whatisthepixelsizeofthedisplay?Compareyouanswerwithpreviousmeasurement.Also,whatisthefillfactor,orwhatpercentofeachpixelisthenontransparentpartoftheliquidcrystalcell?Includeerror.Section3:DiffractiveOpticsObjectives: DiffractiveOpticalElements(DOE’s)differfromtheclassicalopticalelementslikelensesandmirrorsbecausetheyarebasedontheirdiffractivepropertiesratherthanreflectionandrefraction.Whendealingwiththetraditionalopticalelements,diffractionphenomenaareconsideredasundesirablefeatures,whichinfluencestheperformanceofanopticalsystemandhenceshouldbeminimized.DOE’s,ontheotherhand,makeuseofdiffractiontomanipulatethewaveformofanincomingbeamoflight.BecauseofthenatureofdiffractionmostlyhighlymonochromaticandcoherentlightisusedwithDOE’s.Thefirstapplicationofwavefrontmanipulationwasholography.Holographyinspiredpeopletowavefrontprocessinginwhichthe
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surfaceofasubstratewasprocessedtochangeaninputwavefrontintoanotherform.Inprinciplelensesandotherclassicalopticalelementsareallwavefrontprocessers,buttheirfunctionalityislimitedtorelativesimpleactions.DOE’sallowformorecomplexwavefrontmanipulationsandresultedinmodernopticalapplicationsas‘holographicheadupdisplays’infighterjetsandrecentlyinautomobiles.
FresnelZoneLens(FZL)
TheopticalsetupforthisexperimentisilluminatingtheLCDwithaexpandedandcollimatedlaserbeam.OpenthesoftwareOptiXplorerandgotoElementaryOpticalFunctions→FresnelZoneLenses.Settheinnerradiusto35pixels.Measurethedistancebetweenthelensplaneandthenthfocus;thisisthefocaldistancef.Fromyourmeasurementsandtheformulafortheinnermostradiusofabinaryzonelens,
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r = n ⋅ λ ⋅ f Eq.4
determineonceagainthepixelsizeoftheLCdisplay.Comparewithyourpreviousresults.Q5)Wheredoesequation3comefrom?Justabriefdescriptionisneeded.[Hint:Pedrotti136]
Focallengthofthediffractivelens
UsingtheOptiXplorersoftwareaddressablankscreenontheSLM.Withthetoolbarattherightwindowedgealensphasewillbeadded.FindthefocuscreatedbythisDOEandthecorrespondingfocallength.Forewarning,thefocallengthcangrowtoadistanceof3metersataphaseof25,soareasonablephasewouldbegreaterthan100.
CreatingandoptimizingaDOE
Addaf=250mmlensbehindtheSLMfollowedbyaf=30mmlens.Downloadanimage–lessthan200x200pixels–fromtheInternetoruploadonefromyourcamera/phoneintoafolder.IntheOptiXplorersoftwaregotoFile→OpenImageFileanduploadyourimage.Next,clickthe“ComputeDOE”buttonintheupperrightcorneroftheimage.Adjustyoursetupuntilyouseeyourimageasadiffractionpatternonthescreen. Usually,whenreconstructingaDOEthereisadisturbingbrightpointinthemiddle,thezeroorder.UsingadivergingrefractivelensandadiffractiveconverginglensaddedtotheDOE,onecouldspatiallyseparatethereconstructionplanesofthezeroandfirstorder.Beginbyremovingthef=250mmlensandbyreplacingitwith
Pg.10
af=150mmlensinfrontoftheSLM.CreateaDOEfromtheexamplesincludedwiththeOptiXplorersoftwarea.k.a.“grid.bmp”or“cords.bmp”.Fordifferentlensphases,thefocusplaneandtheFourierplaneisfocusedonthescreenbymovingthediverginglens.Forseveraldifferentlensphases,findthedifferencebetweenthefocusofthediffractedlightandthefocusoftheundiffractedlight.
Figure7.Anaddedlensphasecausesafocusingofthediffractedlight(red).Theundiffracted
lightisfocusedbehindthescreen(black).
ByaddingaprismphasetotheaddressedDOEisalsopossibletoseparatetheorders.Thediffractionpatternwillbeshiftedinthexandydirections(seefigure6).RemovethepositivelensinfrontoftheSLMandreplacethedivergingonewithaf=100mmlens.Adjustyousetupinsuchawayastoclearlyseetheimageontheprojectorscreen.Fordifferentprismphasevaluesrecordtheshiftofthediffractionpattern.
Figure8:Top:focusedzeroorder;Left:zeroorderdefocused;Right:diffractionpatternshifted
Section4:InterferometricmeasurementofthephasemodulationObjectives: Thephasemodulationthatcanbeachievedwithaspatiallightmodulatorforacoherentlightsourcecanbemeasuredwithatwo‐beaminterferencesetup.Two
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coherentandcollimatedlaserbeamscreatedbyadouble‐holemaskilluminatethedisplay.BothbeamsareseparatelyguidedtoanappropriatehalfoftheLCD.Theleftonewillbeaddressedwithaconstantgreylevelwhereastheotherhalfwillbeaddressedwithgreylevelsvaryingfrom0to255.AlensbehindthedisplayletsbothbeamsinterferewithoneanotherandamicroscopeobjectiveimagestheexpandedinterferencepatternontoaCCDcamera.Aphaseshiftasafunctionoftheaddressedgreylevelwillappearasashiftintheinterferencepatternperpendiculartotheopticalaxis.
Fig.9:Phasepatternsusedtodeterminethephasemodulation.
PhaseMeasurement
Theopticalsetupisshowninfigure7.Thelasermoduleemitsacollimatedbeam.Constructadouble‐holemaskwithholediameter~3mmandapertureseparation~7mm.Placethismaskintoyouropticalsystemsotwobeamsarecreatedandeachpassesthroughonehalfofthedisplay.AlinearpolarizerinfrontoftheSLMsetstheincomingpolarizationstate.ThelaseremitsellipticalpolarizedlightsotheintensityisdependentonboththeSLMandthefirstpolarizer’sstate.Toremovethisambiguitywemustsettheintensityofthelightleavingthefirstpolarizertobeindependentoftheangle.Q6)Howcanyoudothis?[Hint:Useapolarizerandawaveplate]
Usinganf=250mmlensandanobjectivelens(20x/0.4)imagetheinterferencepatternontotheCCDcamera.OpenthesoftwarePhaseCamandviewtheinterferencepattern.
Figure10:Twobeaminterferometertodetectthephaseshift
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ThePhaseCamsoftwareoffersanautomatedmeasurementoftheshiftintheinterferencepattern.Beginbyselectingthe“Preview”buttontomakesuretheinterferencepatternhasgoodcontrastandthedetectorisnotsaturated.Onceeverythingisproperlyadjustedpush“TestImage”.Astableimageoftheinterferencepatternwillbedisplayed.Byclickingtherightmousebuttoninsideoftheimageaparticularintensitylineisselected.Press“ReadoutLines”toshowasinusoidalintensityprofile.Iftheprofileseemsjitteryanduneven,increasethe“Averaging”numberuntiltheprofileissmooth.OpenthegraylevelwindowusingthecorrespondingbuttonandmakesurethatisoccupiesthefullscreenoftheLCD.Beforestartingthemeasurements,theincrementshavetobechosen.Thisoptionchangesthetimeandtheresolutionofonemeasurement.Thisisalwaysacompromisesincefastmeasurementshavealowresolutionandslowmeasurementshaveahighresolution. The“Start”buttonstartsthemeasurementandgraylevelsvaryingfrom0to255areaddressedontotheactivehalfofthegreylevelwindowinsuccession.Oncethesoftwareisdone,minimizethegreyvaluewindow.YoushouldseesomethingsimilartoFigure10below.Bypushing“ShowMeasurementPoints”aftertheimageisshown,themeasurementspointswillappearasreddots.Savethedataandopen
Figure11:PhaseCamSoftware
itinExcel.Somemeasurementpointswillhave“jumped”tothenextminimum.Thisissimplyfixedbyaddingorsubtractingtheperiodfromthesemeasurements.Findthevalueof∆yorthedistancetheminimumshiftedfromtheinitialminimum(grayvalueof0).Fromthismeasurementandtheperiod,plotthephaseshift,∆ϕ,asafunctionofgreylevel.Repeatthisprocedurefordifferentpolarizerandanalyzerconfigurations.Youwillneedthefollowingequationtodeterminephaseshift.
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Δϕ =2πg⋅ Δy Eq.5
Phase Cam
-15-
6 Evaluation
6.1 Show image
If one presses this button when the measurement is finished an image will appear at the position of the former live image in which the selected measurement line for each addressed gray level is drawn one below the other. This image gives the first impression of the measurement and shows clearly if and how the interference pattern is shifted. A convenient function for the first rough determination of the total phase shift is implemented. If the user moves the cursor into the shown image and presses the right mouse button, a bar will appear at the position of the cursor. If the user holds the button and moves the cursor, a second bar appears and the distance in pixel will be shown just above the image (see figure 10). If the start and the end value are chosen for both bars one can see how far the interference pattern was shifted during the measurements. By taking the period of the interference pattern into account (see 4.2) the phase shift can easily be calculated.
FIG. 10: Metering bars
6.2 Show measurement points
If this button is pressed after the above explained image is shown, the measurement points (values with min intensity) will appear as red points. If the distribution of these points has no big jumps and irregularities (which can be introduced by vibrations or air flow) the measurement will be evaluable. It is
Pg.13
Reference:Goodman,JosephW.IntroductiontoFourierOptics.NewYork,NewYork:TheMcGraw‐HillCompanies,1968Hecht,Eugene.Optics4thEdition.MenloPark,California:AddisonWesleyLongman,2002OptiXplorerEducationKitManual.HoloeyePhotonicsAG,2002
