光测力学典型习题

编号：6BY学号名称：现代光测力学姓名：日期:邮箱:成绩:签名:QUESTION1(15POINTS):ElucidatethefundamentalprincipleofholographybasedonthefollowingsystemsshowninFig.1(a)and1(b).LaserMirrorMirrorFig.1(a)RecordingsystemShutterBeamexpanderPhotographicplateBeamexpanderrig-i(b)ReconstruclionsystemLaserMirrorMirrorFig.1(a)RecordingsystemShutterBeamexpanderPhotographicplateBeamexpanderrig-i(b)Reconstruclionsystema:HolographicRecordingLaserwithsufficientcoherenceissplitintotwowavesbyabeamsplitterplacedinthesystem.Thefirstwave,calledtheobjectwave,isusedtoilluminatestheobject.Itisthenscatteredattheobjectsurfaceandreflectedtothephotographicplate.Thesecondwave,calledthereferencewave,illuminatesthephotographicplatedirectly.Thesetwowaveswillinterferewitheachothertoformaninterferencepatternonthephotographicplate.b:HolographicReconstructionTheoriginalobjectwavecanbereconstructedbyilluminatingthehologramwiththeoriginalreferencewave.Anobservercanseeavirtualimage,whichisindistinguishablefromtheoriginalobject.QUESTION2(15POINTS):Elucidatethefundamentalprincipleofspeckleinterferometryformeasuringin-planedisplacementsbasedonthesystemofFig.2.Laser//Fig.2In-planedisplacementmeasurementsystemImageplaneImaginglensLaser^ObjectplaneLaser//Fig.2In-planedisplacementmeasurementsystemImageplaneImaginglensLaser^ObjectplaneTwobeamsoflaserlocatedintheplaneperpendiculartothey°axisareusedilluminatesymmetricallytheobjectplane.Twoseriesofexposure,onebeforeandtheotherafterdeformation,arerecordedonaphotographicplate.Therecordedspecklegramwillgeneratecontourfringescharacterizingthein-planedisplacementcomponentalongthexdirectionwhenitissubjectedtofiltering.QUESTION3(15POINTS):Elucidatethefundamentalprincipleofgeometricmoir6formeasurementofplanestrains,asshowninFig.3.

Specimen纲tinSpecimen纲tin修Planestrainmeasurementneedstobedividedintotwosteps.Inthefirststep,thegratinglinesofthereferenceandspecimengratingswiththesamepitchpareplacedinthedirectionparalleltothexaxis,asshowninFig.3.Whentheobjectissubjectedtoaplanedeformation,thespecimengratingwillhavethesamedeformationastheobjectandhavethepitchp'afterdeformation.Since£makesthegratinglinesofthespecimengratingelongateorcontractinthexdirectionand0makesthegratinglinesofthespecimengratingymovealongthexdirection,£and0cannotcausemoirefringes.However,£makesthepitchofthespecimengratingenlargeorshrinkand0makesthegratinglinesofthespecimengratingrotate,therefore£and0willcausemoirefringes.Inthesecondstep,thegratinglinesofthereferenceandspecimengratingsareparalleltotheyaxisandassumethatthepitchofthespecimengratingispbeforedeformationandp'afterdeformation.£makesthegratinglinesofthespecimengratingelongateorcontractintheydirectionandymakesthegratinglinesofthespecimengratingmovealongtheydirection,hence£alongtheydirection,hence£and°cannotcausemoirefringes.However,£makesthepitchofthespecimengratingenlargeorshrinkand0makesthegratinglinesofthespecimengratingrotate,therefore£and0willproducemoirefringes.QUESTION4(15POINTS):Double-exposureholographicinterferometryisadoptedtomeasuretheout-of-planerotationofacircularplate.AssumingthattheilluminationandobservationarebothperpendiculartothesurfaceoftheplateandthataHe-Nelaser(九二632.8nm)isusedtoilluminatethespecimen,determinetheout-of-planedisplacementofpointAwithrespecttopointBinthefollowingfigureifAandBarerespectivelylocatedonthecenterlinesoftwofringes.

n n九 7义632.8A位于第7级亮纹d=二-= =2214.8nmA2 2(n+5)入B位于第-8级暗纹d= =2689.4nmB2d=dA—dB=4904.2nmQUESTION5(10POINTS):Fourfringepatternshavephase-shiftingvalues0,n/2,nand3n/2respectively,calculateanddisplaythewrappedphasemap.(3)Programusedfordisplayingtheabovewrappedphasemapcloseall;clearall;clc;A=im2double(imread('Fig.5(1).tif'));B=im2double(imread('Fig.5(2).tif'));C=im2double(imread('Fig.5(3).tif'));D=im2double(imread('Fig.5(4).tif'));E=D-B;F=A-C;P=atan2(real(E),real(F));Q=unwrap(P);

Q=mat2gray(Q,[0,max(Q(:))]);imwrite(Q,'figT005.tif');imshow(Q,[])QUESTION6(10POINTS):Denoisethefollowingfringepattern.Fringepattern:(2)DenoisedfringeIdeallow-pasProgramusedfordenoisingtheabovefringepattern:closeall;clearall;clc;(2)DenoisedfringeIdeallow-pasA=im2double(imread('Fig.6.tif'));D=fftshift(fft2(A));[N1,N2]=size(D);d0=360;n1=floor(N1/2);n2=floor(N2/2);fori=1:N1forj=1:N2d=sqrt((i-n1)人2+(j-n2)人2);ifd>=d0h=0;

elseh=1;endC(i,j)=h.*D(i,j);endendZ=ifft2(C);U=Z.*conj(Z);U=mat2gray(U,[0,max(U(:))]);imwrite(U,'T066.tif');imshow(U,[])QUESTION7(10POINTS):Knowingthat九=0.6328目m,followingdigitalhologram.Ax=Ay=Ax=Ay=3.2^m,andz=-1.0m,reconstructthevirtualimageoftheProgramusedfortheabovedigitalhologram:closeall;clearall;clc;A=im2double(imread('Fig.7.tif'));lambda=0.6328e-6;k=2*pi/lambda;dx=3.2e-6;dy=3.2e-6;z=-1;S=size(A);dxr=lambda*z/(S(1).*dx);dyr=lambda*z/(S(2).*dy);[X1,X2]=ndgrid(0:S(1)-1,0:S(2)-1);B=exp(1i*k*z)/(1i*lambda*z)*exp(1i*pi/(lambda*z)*((X1*dxr)-2+(X2*dyr)J2));C=exp(1i*pi)/(lambda*z)*((X1*dx)-2+(X2*dy)J2);D=B.*fftshift(fft2(A.*C));P=atan2(imag(D),real(D));im