What is the difference between interference and diffraction?

Sheet1

theta sin pi*d/l beta alpha total LAMBDA (m) d (m) a (m)
0 0 235.61925 0 0 1 4.00E-07 3.00E-05 4.00E-06
0.0005 0.0005 235.61925 0.1178096201 0.0157079493 0.9861038769
0.001 0.0009999998 235.61925 0.2356192107 0.0314158948 0.9451923537
0.0015 0.0014999994 235.61925 0.3534287425 0.0471238323 0.8795519129
0.002 0.0019999987 235.61925 0.4712381858 0.0628317581 0.7928490337
0.0025 0.0024999974 235.61925 0.5890475114 0.0785396682 0.6899224002
0.003 0.0029999955 235.61925 0.7068566897 0.0942475586 0.5765088664
0.0035 0.0034999929 235.61925 0.8246656913 0.1099554255 0.4589188714
0.004 0.0039999893 235.61925 0.9424744867 0.1256632649 0.3436798768
0.0045 0.0044999848 235.61925 1.0602830465 0.1413710729 0.2371681996
0.005 0.0049999792 235.61925 1.1780913413 0.1570788455 0.1452502423
0.0055 0.0054999723 235.61925 1.2958993415 0.1727865789 0.0729535337
0.006 0.005999964 235.61925 1.4137070177 0.188494269 0.0241862387
0.0065 0.0064999542 235.61925 1.5315143405 0.2042019121 0.0015209629
0.007 0.0069999428 235.61925 1.6493212805 0.2199095041 0.0060549474
0.0075 0.0074999297 235.61925 1.7671278081 0.2356170411 0.037354333
0.008 0.0079999147 235.61925 1.8849338939 0.2513245192 0.0934853297
0.0085 0.0084998976 235.61925 2.0027395085 0.2670319345 0.171130142
0.009 0.0089998785 235.61925 2.1205446224 0.282739283 0.2657806585
0.0095 0.0094998571 235.61925 2.2383492061 0.2984465608 0.3719984952
0.01 0.0099998333 235.61925 2.3561532303 0.314153764 0.4837262455
0.0105 0.0104998071 235.61925 2.4739566655 0.3298608887 0.5946319379
0.011 0.0109997782 235.61925 2.5917594821 0.3455679309 0.6984669091
0.0115 0.0114997465 235.61925 2.7095616508 0.3612748868 0.789416648
0.012 0.011999712 235.61925 2.8273631421 0.3769817523 0.8624247018
0.0125 0.0124996745 235.61925 2.9451639266 0.3926885235 0.9134714059
0.013 0.0129996338 235.61925 3.0629639748 0.4083951966 0.9397919136
0.0135 0.0134995899 235.61925 3.1807632573 0.4241017676 0.940021584
0.014 0.0139995427 235.61925 3.2985617445 0.4398082326 0.9142610349
0.0145 0.0144994919 235.61925 3.4163594071 0.4555145876 0.8640578195
0.015 0.0149994375 235.61925 3.5341562157 0.4712208288 0.7923064815
0.0155 0.0154993794 235.61925 3.6519521407 0.4869269521 0.7030733921
0.016 0.0159993173 235.61925 3.7697471527 0.5026329537 0.6013570189
0.0165 0.0164992513 235.61925 3.8875412222 0.5183388296 0.4927978669
0.017 0.0169991812 235.61925 4.0053343199 0.534044576 0.3833550733
0.0175 0.0174991068 235.61925 4.1231264162 0.5497501888 0.2789683787
0.018 0.017999028 235.61925 4.2409174818 0.5654556642 0.185224836
0.0185 0.0184989447 235.61925 4.3587074871 0.5811609983 0.1070491489
0.019 0.0189988569 235.61925 4.4764964028 0.596866187 0.0484349727
0.0195 0.0194987642 235.61925 4.5942841993 0.6125712266 0.0122319739
0.02 0.0199986667 235.61925 4.7120708473 0.628276113 0.0000000886
0.0205 0.0204985642 235.61925 4.8298563172 0.6439808423 0.0119384431
0.021 0.0209984565 235.61925 4.9476405797 0.6596854106 0.0468920401
0.0215 0.0214983436 235.61925 5.0654236053 0.675389814 0.1024348316
0.022 0.0219982254 235.61925 5.1832053645 0.6910940486 0.1750234513
0.0225 0.0224981016 235.61925 5.3009858279 0.7067981104 0.2602119159
0.023 0.0229979722 235.61925 5.4187649661 0.7225019955 0.3529142517
0.0235 0.0234978371 235.61925 5.5365427495 0.7382056999 0.447699444
0.024 0.0239976961 235.61925 5.6543191489 0.7539092199 0.5391014832
0.0245 0.0244975491 235.61925 5.7720941346 0.7696125513 0.6219266664
0.025 0.0249973959 235.61925 5.8898676774 0.7853156903 0.6915407381
0.0255 0.0254972365 235.61925 6.0076397476 0.801018633 0.7441198711
0.026 0.0259970708 235.61925 6.125410316 0.8167213755 0.7768518045
0.0265 0.0264968985 235.61925 6.243179353 0.8324239137 0.7880765229
0.027 0.0269967196 235.61925 6.3609468292 0.8481262439 0.7773594907
0.0275 0.027496534 235.61925 6.4787127152 0.863828362 0.7454944252
0.028 0.0279963415 235.61925 6.5964769815 0.8795302642 0.6944366761
0.0285 0.028496142 235.61925 6.7142395987 0.8952319465 0.6271722229
0.029 0.0289959353 235.61925 6.8320005373 0.910933405 0.5475308985
0.0295 0.0294957215 235.61925 6.9497597679 0.9266346357 0.4599554804
0.03 0.0299955002 235.61925 7.0675172611 0.9423356348 0.3692406009
0.0305 0.0304952714 235.61925 7.1852729874 0.9580363983 0.2802568918
0.031 0.0309950351 235.61925 7.3030269174 0.9737369223 0.1976763318
0.0315 0.0314947909 235.61925 7.4207790216 0.9894372029 0.1257143821
0.032 0.0319945389 235.61925 7.5385292706 1.0051372361 0.0679032301
0.0325 0.0324942789 235.61925 7.656277635 1.020837018 0.0269083905
0.033 0.0329940108 235.61925 7.7740240853 1.0365365447 0.0043981789
0.0335 0.0334937345 235.61925 7.8917685922 1.0522358123 0.0009723535
0.034 0.0339934497 235.61925 8.009511126 1.0679348168 0.0161526929
0.0345 0.0344931565 235.61925 8.1272516575 1.0836335543 0.0484346787
0.035 0.0349928546 235.61925 8.2449901572 1.099332021 0.0953959673
0.0355 0.035492544 235.61925 8.3627265957 1.1150302128 0.1538541816
0.036 0.0359922245 235.61925 8.4804609434 1.1307281258 0.2200638988
0.0365 0.036491896 235.61925 8.5981931711 1.1464257561 0.2899406983
0.037 0.0369915584 235.61925 8.7159232492 1.1621230999 0.3592988691
0.0375 0.0374912116 235.61925 8.8336511483 1.1778201531 0.4240889156
0.038 0.0379908553 235.61925 8.951376839 1.1935169119 0.480621344
0.0385 0.0384904896 235.61925 9.0691002918 1.2092133722 0.5257643376
0.039 0.0389901143 235.61925 9.1868214774 1.2249095303 0.5571047319
0.0395 0.0394897292 235.61925 9.3045403663 1.2406053822 0.5730640776
0.04 0.0399893342 235.61925 9.4222569291 1.2563009239 0.572964366
0.0405 0.0404889292 235.61925 9.5399711362 1.2719961515 0.5570410255
0.041 0.0409885141 235.61925 9.6576829584 1.2876910611 0.5264038824
0.0415 0.0414880888 235.61925 9.7753923662 1.3033856488 0.4829497535
0.042 0.0419876531 235.61925 9.8930993301 1.3190799107 0.4292330106
0.0425 0.0424872069 235.61925 10.0108038207 1.3347738428 0.3683026955
0.043 0.0429867501 235.61925 10.1285058087 1.3504674412 0.3035164459
0.0435 0.0434862825 235.61925 10.2462052645 1.3661607019 0.2383425263
0.044 0.043985804 235.61925 10.3639021588 1.3818536212 0.1761616182
0.0445 0.0444853146 235.61925 10.4815964621 1.3975461949 0.1200796903
0.045 0.044984814 235.61925 10.5992881449 1.4132384193 0.0727622948
0.0455 0.0454843022 235.61925 10.716977178 1.4289302904 0.0362990885
0.046 0.045983779 235.61925 10.8346635318 1.4446218042 0.0121053651
0.0465 0.0464832444 235.61925 10.952347177 1.4603129569 0.0008650435
0.047 0.0469826981 235.61925 11.0700280841 1.4760037445 0.002517027
0.0475 0.04748214 235.61925 11.1877062236 1.4916941632 0.0162842857
0.048 0.0479815701 235.61925 11.3053815663 1.5073842088 0.0407425742
0.0485 0.0484809882 235.61925 11.4230540826 1.5230738777 0.0739235104
0.049 0.0489803942 235.61925 11.5407237431 1.5387631657 0.1134449349
0.0495 0.0494797879 235.61925 11.6583905184 1.5544520691 0.1566601362
0.05 0.0499791693 235.61925 11.7760543792 1.5701405839 0.2008167242
0.0505 0.0504785381 235.61925 11.8937152959 1.5858287061 0.2432156993
0.051 0.0509778944 235.61925 12.0113732392 1.6015164319 0.2813615871
0.0515 0.0514772379 235.61925 12.1290281797 1.6172037573 0.3130953493
0.052 0.0519765685 235.61925 12.2466800879 1.6328906784 0.3367030823
0.0525 0.0524758861 235.61925 12.3643289344 1.6485771913 0.3509951711
0.053 0.0529751907 235.61925 12.4819746899 1.664263292 0.3553524791
0.0535 0.0534744819 235.61925 12.5996173249 1.6799489766 0.3497381924
0.054 0.0539737598 235.61925 12.7172568099 1.6956342413 0.334675986
0.0545 0.0544730242 235.61925 12.8348931157 1.7113190821 0.3111971068
0.055 0.054972275 235.61925 12.9525262127 1.727003495 0.2807606741
0.0555 0.0554715121 235.61925 13.0701560716 1.7426874762 0.245152885
0.056 0.0559707353 235.61925 13.1877826629 1.7583710217 0.2063718098
0.0565 0.0564699444 235.61925 13.3054059573 1.7740541276 0.166505033
0.057 0.0569691395 235.61925 13.4230259254 1.78973679 0.1276075085
0.0575 0.0574683203 235.61925 13.5406425377 1.805419005 0.091586682
0.058 0.0579674868 235.61925 13.6582557648 1.8211007686 0.060101208
0.0585 0.0584666388 235.61925 13.7758655774 1.836782077 0.034478525
0.059 0.0589657761 235.61925 13.893471946 1.8524629261 0.0156552215
0.0595 0.0594648987 235.61925 14.0110748412 1.8681433122 0.0041426164
0.06 0.0599640065 235.61925 14.1286742337 1.8838232312 0.0000183964
0.0605 0.0604630992 235.61925 14.246270094 1.8995026792 0.0029435818
0.061 0.0609621769 235.61925 14.3638623927 1.9151816524 0.012202642
0.0615 0.0614612393 235.61925 14.4814511005 1.9308601467 0.0267633213
0.062 0.0619602863 235.61925 14.5990361879 1.9465381584 0.0453517342
0.0625 0.0624593178 235.61925 14.7166176255 1.9622156834 0.0665376043
0.063 0.0629583338 235.61925 14.834195384 1.9778927179 0.0888241655
0.0635 0.063457334 235.61925 14.951769434 1.9935692579 0.1107372354
0.064 0.0639563183 235.61925 15.069339746 2.0092452995 0.130908291
0.0645 0.0644552866 235.61925 15.1869062906 2.0249208388 0.1481469878
0.065 0.0649542388 235.61925 15.3044690386 2.0405958718 0.1614994198
0.0655 0.0654531748 235.61925 15.4220279604 2.0562703947 0.1702894529
0.066 0.0659520944 235.61925 15.5395830267 2.0719444036 0.1741416083
0.0665 0.0664509976 235.61925 15.6571342081 2.0876178944 0.172985151
0.067 0.0669498841 235.61925 15.7746814753 2.1032908634 0.1670401783
0.0675 0.0674487539 235.61925 15.8922247987 2.1189633065 0.156787533
0.068 0.0679476068 235.61925 16.0097641491 2.1346352199 0.1429252387
0.0685 0.0684464427 235.61925 16.1272994971 2.1503065996 0.126314811
0.069 0.0689452615 235.61925 16.2448308133 2.1659774418 0.1079212206
0.0695 0.0694440631 235.61925 16.3623580682 2.1816477424 0.0887504541
0.07 0.0699428473 235.61925 16.4798812325 2.1973174977 0.0697885368
0.0705 0.0704416141 235.61925 16.5974002769 2.2129867036 0.0519455706
0.071 0.0709403632 235.61925 16.7149151719 2.2286553563 0.0360078294
0.0715 0.0714390946 235.61925 16.8324258882 2.2443234518 0.0226002849
0.072 0.0719378081 235.61925 16.9499323964 2.2599909862 0.012161158
0.0725 0.0724365037 235.61925 17.0674346671 2.2756579556 0.0049292653
0.073 0.0729351811 235.61925 17.184932671 2.2913243561 0.0009440952
0.0735 0.0734338403 235.61925 17.3024263786 2.3069901838 0.0000577799
0.074 0.0739324812 235.61925 17.4199157606 2.3226554347 0.0019574448
0.0745 0.0744311035 235.61925 17.5374007876 2.338320105 0.0061958791
0.075 0.0749297073 235.61925 17.6548814303 2.3539841907 0.0122280901
0.0755 0.0754282923 235.61925 17.7723576593 2.3696476879 0.0194510964
0.076 0.0759268585 235.61925 17.8898294452 2.3853105927 0.0272442906
0.0765 0.0764254056 235.61925 18.0072967586 2.4009729011 0.0350078474
0.077 0.0769239337 235.61925 18.1247595702 2.4166346094 0.0421969425
0.0775 0.0774224426 235.61925 18.2422178506 2.4322957134 0.0483499674
0.078 0.0779209321 235.61925 18.3596715704 2.4479562094 0.0531094285
0.0785 0.0784194021 235.61925 18.4771207003 2.4636160934 0.056234772
0.079 0.0789178525 235.61925 18.594565211 2.4792753615 0.0576069466
0.0795 0.0794162831 235.61925 18.712005073 2.4949340097 0.0572250504
0.08 0.079914694 235.61925 18.829440257 2.5105920343 0.0551958946
0.0805 0.0804130848 235.61925 18.9468707336 2.5262494312 0.0517177064
0.081 0.0809114556 235.61925 19.0642964736 2.5419061965 0.0470594836
0.0815 0.0814098061 235.61925 19.1817174474 2.5575623263 0.0415376778
0.082 0.0819081362 235.61925 19.2991336258 2.5732178168 0.0354919314
0.0825 0.0824064459 235.61925 19.4165449795 2.5888726639 0.0292615197
0.083 0.082904735 235.61925 19.533951479 2.6045268639 0.0231639756
0.0835 0.0834030033 235.61925 19.651353095 2.6201804127 0.0174771093
0.084 0.0839012508 235.61925 19.7687497982 2.6358333064 0.0124253159
0.0845 0.0843994774 235.61925 19.8861415592 2.6514855412 0.0081706994
0.085 0.0848976828 235.61925 20.0035283486 2.6671371132 0.0048091766
0.0855 0.085395867 235.61925 20.1209101372 2.6827880183 0.0023713695
0.086 0.0858940299 235.61925 20.2382868956 2.6984382527 0.0008277851
0.0865 0.0863921712 235.61925 20.3556585943 2.7140878126 0.0000975285
0.087 0.086890291 235.61925 20.4730252042 2.7297366939 0.000059611
0.0875 0.0873883891 235.61925 20.5903866958 2.7453848928 0.0005658202
0.088 0.0878864653 235.61925 20.7077430398 2.7610324053 0.0014540922
0.0885 0.0883845195 235.61925 20.8250942069 2.7766792276 0.0025613894
0.089 0.0888825517 235.61925 20.9424401677 2.7923253557 0.0037352095
0.0895 0.0893805616 235.61925 21.0597808929 2.8079707857 0.0048430263
0.09 0.0898785492 235.61925 21.1771163531 2.8236155137 0.0057791844
0.0905 0.0903765143 235.61925 21.2944465191 2.8392595359 0.0064689952
0.091 0.0908744568 235.61925 21.4117713614 2.8549028482 0.0068700195
0.0915 0.0913723766 235.61925 21.5290908509 2.8705454468 0.0069707349
0.092 0.0918702736 235.61925 21.646404958 2.8861873277 0.0067869688
0.0925 0.0923681476 235.61925 21.7637136535 2.9018284871 0.0063566165
0.093 0.0928659985 235.61925 21.8810169081 2.9174689211 0.0057332519
0.0935 0.0933638261 235.61925 21.9983146925 2.9331086257 0.0049792686
0.094 0.0938616305 235.61925 22.1156069773 2.948747597 0.0041591715
0.0945 0.0943594114 235.61925 22.2328937331 2.9643858311 0.0033335663
0.095 0.0948571686 235.61925 22.3501749308 2.9800233241 0.0025542887
0.0955 0.0953549022 235.61925 22.4674505409 2.9956600721 0.0018609782
0.096 0.0958526119 235.61925 22.5847205342 3.0112960712 0.0012792479
0.0965 0.0963502977 235.61925 22.7019848812 3.0269313175 0.0008204514
0.097 0.0968479594 235.61925 22.8192435528 3.042565807 0.0004829024
0.0975 0.0973455968 235.61925 22.9364965195 3.0581995359 0.0002542831
0.098 0.09784321 235.61925 23.0537437522 3.0738325003 0.0001148893
0.0985 0.0983407986 235.61925 23.1709852214 3.0894646962 0.0000413052
0.099 0.0988383627 235.61925 23.2882208978 3.1050961197 0.0000100905
0.0995 0.0993359021 235.61925 23.4054507522 3.120726767 0.0000010858
0.1 0.0998334166 235.61925 23.5226747553 3.136356634 0.0000000043
0.1005 0.1003309062 235.61925 23.6398928776 3.151985717 0.0000000659
0.101 0.1008283707 235.61925 23.75710509 3.167614012 0.0000025372
0.1015 0.10132581 235.61925 23.8743113631 3.1832415151 0.0000161575
0.102 0.101823224 235.61925 23.9915116677 3.1988682224 0.000055546
0.1025 0.1023206125 235.61925 24.1087059743 3.2144941299 0.0001387894
0.103 0.1028179754 235.61925 24.2258942538 3.2301192338 0.000284488
0.1035 0.1033153126 235.61925 24.3430764768 3.2457435302 0.0005085982
0.104 0.103812624 235.61925 24.4602526141 3.2613670152 0.0008214256
0.1045 0.1043099095 235.61925 24.5774226363 3.2769896848 0.0012251157
0.105 0.1048071688 235.61925 24.6945865141 3.2926115352 0.0017119415
0.1055 0.105304402 235.61925 24.8117442183 3.3082325624 0.0022636157
0.106 0.1058016088 235.61925 24.9288957195 3.3238527626 0.0028517591
0.1065 0.1062987892 235.61925 25.0460409885 3.3394721318 0.0034395477
0.107 0.106795943 235.61925 25.163179996 3.3550906661 0.0039844471
0.1075 0.1072930701 235.61925 25.2803127127 3.3707083617 0.0044418352
0.108 0.1077901704 235.61925 25.3974391094 3.3863252146 0.0047692195
0.1085 0.1082872437 235.61925 25.5145591567 3.4019412209 0.004930689
0.109 0.10878429 235.61925 25.6316728253 3.4175563767 0.0049011961
0.1095 0.1092813091 235.61925 25.748780086 3.4331706781 0.0046702621
0.11 0.1097783008 235.61925 25.8658809095 3.4487841213 0.0042447263
0.1105 0.1102752651 235.61925 25.9829752666 3.4643967022 0.0036502226
0.111 0.1107722019 235.61925 26.1000631279 3.4800084171 0.0029311597
0.1115 0.1112691109 235.61925 26.2171444642 3.4956192619 0.0021490942
0.112 0.1117659922 235.61925 26.3342192462 3.5112292328 0.0013795169
0.1125 0.1122628454 235.61925 26.4512874446 3.526838326 0.0007072023
0.113 0.1127596707 235.61925 26.5683490303 3.5424465374 0.0002203995
0.1135 0.1132564677 235.61925 26.6854039738 3.5580538632 0.00000425
0.114 0.1137532364 235.61925 26.802452246 3.5736602995 0.0001339018
0.1145 0.1142499767 235.61925 26.9194938176 3.5892658423 0.000667839
0.115 0.1147466884 235.61925 27.0365286593 3.6048704879 0.0016419561
0.1155 0.1152433714 235.61925 27.1535567419 3.6204742322 0.0030648797
0.116 0.1157400256 235.61925 27.2705780361 3.6360770715 0.0049149682
0.1165 0.1162366509 235.61925 27.3875925126 3.6516790017 0.0071393198
0.117 0.1167332471 235.61925 27.5046001422 3.667280019 0.0096549821
0.1175 0.1172298142 235.61925 27.6216008957 3.6828801194 0.0123524055
0.118 0.1177263519 235.61925 27.7385947438 3.6984792992 0.0151010195
0.1185 0.1182228602 235.61925 27.8555816573 3.7140775543 0.0177566501
0.119 0.118719339 235.61925 27.9725616068 3.7296748809 0.0201703517
0.1195 0.119215788 235.61925 28.0895345632 3.7452712751 0.0221981045
0.12 0.1197122073 235.61925 28.2065004973 3.760866733 0.0237107436
0.1205 0.1202085966 235.61925 28.3234593797 3.7764612506 0.0246034412
0.121 0.1207049559 235.61925 28.4404111812 3.7920548242 0.0248040663
0.1215 0.121201285 235.61925 28.5573558726 3.8076474497 0.024279795
0.122 0.1216975838 235.61925 28.6742934247 3.8232391233 0.023041442
0.1225 0.1221938522 235.61925 28.7912238082 3.8388298411 0.0211451173
0.123 0.12269009 235.61925 28.908146994 3.8544195992 0.0186909804
0.1235 0.1231862972 235.61925 29.0250629526 3.8700083937 0.0158190532
0.124 0.1236824735 235.61925 29.1419716551 3.8855962207 0.0127022498
0.1245 0.124178619 235.61925 29.258873072 3.9011830763 0.0095369715
0.125 0.1246747334 235.61925 29.3757671742 3.9167689566 0.0065317933
0.1255 0.1251708166 235.61925 29.4926539324 3.9323538577 0.0038949098
0.126 0.1256668685 235.61925 29.6095333175 3.9479377757 0.0018211122
0.1265 0.1261628891 235.61925 29.7264053003 3.9635207067 0.0004791236
0.127 0.126658878 235.61925 29.8432698514 3.9791026468 0.0000001207
0.1275 0.1271548354 235.61925 29.9601269417 3.9946835922 0.000468216
0.128 0.1276507609 235.61925 30.0769765419 4.0102635389 0.0019135705
0.1285 0.1281466545 235.61925 30.1938186229 4.0258424831 0.0043086525
0.129 0.1286425161 235.61925 30.3106531555 4.0414204207 0.0075679711
0.1295 0.1291383455 235.61925 30.4274801104 4.0569973481 0.0115513966
0.13 0.1296341426 235.61925 30.5442994584 4.0725732611 0.0160709539
0.1305 0.1301299073 235.61925 30.6611111704 4.0881481561 0.0209007509
0.131 0.1306256395 235.61925 30.7779152171 4.1037220289 0.0257894976
0.1315 0.1311213391 235.61925 30.8947115693 4.1192948759 0.0304748953
0.132 0.1316170058 235.61925 31.0115001978 4.134866693 0.0346990442
0.1325 0.1321126397 235.61925 31.1282810735 4.1504374765 0.0382239354
0.133 0.1326082405 235.61925 31.245054167 4.1660072223 0.0408460733
0.1335 0.1331038082 235.61925 31.3618194494 4.1815759266 0.0424093093
0.134 0.1335993425 235.61925 31.4785768912 4.1971435855 0.0428150677
0.1345 0.1340948435 235.61925 31.5953264634 4.2127101951 0.0420292906
0.135 0.134590311 235.61925 31.7120681368 4.2282757516 0.0400856262
0.1355 0.1350857448 235.61925 31.8288018822 4.243840251 0.0370846076
0.136 0.1355811449 235.61925 31.9455276704 4.2594036894 0.0331888159
0.1365 0.136076511 235.61925 32.0622454721 4.274966063 0.0286142688
0.137 0.1365718432 235.61925 32.1789552584 4.2905273678 0.0236185084
0.1375 0.1370671412 235.61925 32.2956569999 4.3060876 0.0184860736
0.138 0.1375624049 235.61925 32.4123506674 4.3216467557 0.0135122039
0.1385 0.1380576342 235.61925 32.5290362319 4.3372048309 0.0089857424
0.139 0.138552829 235.61925 32.6457136641 4.3527618219 0.0051722571
0.1395 0.1390479892 235.61925 32.7623829349 4.3683177247 0.002298397
0.14 0.1395431146 235.61925 32.8790440151 4.3838725354 0.0005384275
0.1405 0.1400382052 235.61925 32.9956968756 4.3994262501 0.0000037663
0.141 0.1405332607 235.61925 33.1123414871 4.4149788649 0.0007361573
0.1415 0.1410282811 235.61925 33.2289778205 4.4305303761 0.0027049073
0.142 0.1415232662 235.61925 33.3456058467 4.4460807796 0.0058083632
0.1425 0.142018216 235.61925 33.4622255365 4.4616300715 0.0098795519
0.143 0.1425131302 235.61925 33.5788368607 4.4771782481 0.0146956554
0.1435 0.1430080089 235.61925 33.6954397903 4.4927253054 0.0199907616
0.144 0.1435028517 235.61925 33.8120342959 4.5082712395 0.0254711357
0.1445 0.1439976587 235.61925 33.9286203486 4.5238160465 0.0308321045
0.145 0.1444924297 235.61925 34.0451979191 4.5393597225 0.0357755549
0.1455 0.1449871646 235.61925 34.1617669783 4.5549022638 0.0400270089
0.146 0.1454818632 235.61925 34.278327497 4.5704436663 0.0433512703
0.1465 0.1459765255 235.61925 34.3948794462 4.5859839262 0.0455657264
0.147 0.1464711512 235.61925 34.5114227967 4.6015230396 0.0465505324
0.1475 0.1469657404 235.61925 34.6279575193 4.6170610026 0.0462550978
0.148 0.1474602928 235.61925 34.7444835849 4.6325978113 0.0447005158
0.1485 0.1479548083 235.61925 34.8610009644 4.6481334619 0.0419778255
0.149 0.1484492868 235.61925 34.9775096286 4.6636679505 0.0382422398
0.1495 0.1489437283 235.61925 35.0940095485 4.6792012731 0.0337037162
0.15 0.1494381325 235.61925 35.2105006948 4.694733426 0.0286144569
0.1505 0.1499324993 235.61925 35.3269830386 4.7102644051 0.023254104
0.151 0.1504268287 235.61925 35.4434565506 4.7257942067 0.0179135225
0.1515 0.1509211204 235.61925 35.5599212017 4.7413228269 0.012878137
0.152 0.1514153744 235.61925 35.6763769628 4.7568502617 0.0084118026
0.1525 0.1519095906 235.61925 35.7928238049 4.7723765073 0.0047421459
0.153 0.1524037688 235.61925 35.9092616987 4.7879015598 0.0020482117
0.1535 0.1528979089 235.61925 36.0256906153 4.8034254154 0.0004511012
0.154 0.1533920107 235.61925 36.1421105254 4.81894807 0.0000081016
0.1545 0.1538860742 235.61925 36.2585214 4.83446952 0.0007105901
0.155 0.1543800993 235.61925 36.3749232099 4.8499897613 0.0024857689
0.1555 0.1548740857 235.61925 36.4913159261 4.8655087902 0.0052020592
0.156 0.1553680335 235.61925 36.6076995195 4.8810266026 0.0086777693
0.1565 0.1558619424 235.61925 36.724073961 4.8965431948 0.0126924666
0.157 0.1563558123 235.61925 36.8404392214 4.9120585629 0.0170003326
0.1575 0.1568496431 235.61925 36.9567952718 4.9275727029 0.0213446807
0.158 0.1573434347 235.61925 37.0731420829 4.9430856111 0.0254727634
0.1585 0.157837187 235.61925 37.1894796258 4.9585972834 0.0291499983
0.159 0.1583308998 235.61925 37.3058078713 4.9741077162 0.0321727978
0.1595 0.1588245731 235.61925 37.4221267903 4.9896169054 0.034379288
0.16 0.1593182066 235.61925 37.5384363538 5.0051248472 0.0356573457
0.1605 0.1598118003 235.61925 37.6547365327 5.0206315377 0.0359495541
0.161 0.1603053541 235.61925 37.7710272979 5.0361369731 0.0352548736
0.1615 0.1607988678 235.61925 37.8873086204 5.0516411494 0.0336270195
0.162 0.1612923412 235.61925 38.003580471 5.0671440628 0.0311697382
0.1625 0.1617857744 235.61925 38.1198428207 5.0826457094 0.028029348
0.163 0.1622791671 235.61925 38.2360956405 5.0981460854 0.024385065
0.1635 0.1627725192 235.61925 38.3523389012 5.1136451868 0.0204377485
0.164 0.1632658307 235.61925 38.4685725739 5.1291430099 0.0163977743
0.1645 0.1637591013 235.61925 38.5847966294 5.1446395506 0.0124727765
0.165 0.164252331 235.61925 38.7010110387 5.1601348052 0.008855978
0.1655 0.1647455196 235.61925 38.8172157728 5.1756287697 0.0057157751
0.166 0.1652386671 235.61925 38.9334108026 5.1911214403 0.003187142
0.1665 0.1657317732 235.61925 39.049596099 5.2066128132 0.0013652939
0.167 0.1662248379 235.61925 39.165771633 5.2221028844 0.0003018966
0.1675 0.166717861 235.61925 39.2819373756 5.2375916501 0.0000039486
0.168 0.1672108425 235.61925 39.3980932976 5.2530791064 0.0004352987
0.1685 0.1677037821 235.61925 39.5142393702 5.2685652494 0.001520602
0.169 0.1681966799 235.61925 39.6303755642 5.2840500752 0.0031513834
0.1695 0.1686895356 235.61925 39.7465018506 5.2995335801 0.0051937623
0.17 0.1691823491 235.61925 39.8626182004 5.3150157601 0.00749731
0.1705 0.1696751203 235.61925 39.9787245845 5.3304966113 0.0099044664
0.171 0.1701678491 235.61925 40.094820974 5.3459761299 0.0122599324
0.1715 0.1706605353 235.61925 40.2109073397 5.361454312 0.0144194815
0.172 0.1711531789 235.61925 40.3269836527 5.3769311537 0.0162576926
0.1725 0.1716457797 235.61925 40.443049884 5.3924066512 0.017674194
0.173 0.1721383376 235.61925 40.5591060045 5.4078808006 0.018598119
0.1735 0.1726308525 235.61925 40.6751519853 5.423353598 0.0189905928
0.174 0.1731233242 235.61925 40.7911877972 5.4388250396 0.0188452017
0.1745 0.1736157526 235.61925 40.9072134114 5.4542951215 0.01818652
0.175 0.1741081376 235.61925 41.0232287987 5.4697638398 0.0170668842
0.1755 0.1746004791 235.61925 41.1392339302 5.4852311907 0.0155617027
0.176 0.1750927769 235.61925 41.255228777 5.5006971703 0.0137636646
0.1765 0.175585031 235.61925 41.3712133099 5.5161617747 0.0117762601
0.177 0.1760772411 235.61925 41.4871875 5.531625 0.009707044
0.1775 0.1765694073 235.61925 41.6031513183 5.5470868424 0.0076610701
0.178 0.1770615293 235.61925 41.7191047359 5.5625472981 0.0057348857
0.1785 0.177553607 235.61925 41.8350477236 5.5780063632 0.0040114232
0.179 0.1780456404 235.61925 41.9509802526 5.5934640337 0.0025560473
0.1795 0.1785376292 235.61925 42.0669022939 5.6089203059 0.0014139313
0.18 0.1790295734 235.61925 42.1828138184 5.6243751758 0.0006088405
0.1805 0.1795214729 235.61925 42.2987147972 5.6398286396 0.0001433084
0.181 0.1800133274 235.61925 42.4146052014 5.6552806935 0.000000104
0.1815 0.180505137 235.61925 42.5304850019 5.6707313336 0.0001448105
0.182 0.1809969014 235.61925 42.6463541698 5.686180556 0.0005292792
0.1825 0.1814886206 235.61925 42.762212676 5.7016283568 0.0010956788
0.183 0.1819802944 235.61925 42.8780604918 5.7170747322 0.0017808398
0.1835 0.1824719228 235.61925 42.993897588 5.7325196784 0.002520596
0.184 0.1829635055 235.61925 43.1097239357 5.7479631914 0.0032538437
0.1845 0.1834550424 235.61925 43.225539506 5.7634052675 0.0039260766
0.185 0.1839465335 235.61925 43.34134427 5.7788459027 0.0044922064
0.1855 0.1844379786 235.61925 43.4571381986 5.7942850931 0.0049185383
0.186 0.1849293776 235.61925 43.5729212629 5.8097228351 0.0051838373
0.1865 0.1854207304 235.61925 43.688693434 5.8251591245 0.0052794871
0.187 0.1859120368 235.61925 43.8044546829 5.8405939577 0.0052088024
0.1875 0.1864032968 235.61925 43.9202049807 5.8560273308 0.004985612
0.188 0.1868945101 235.61925 44.0359442984 5.8714592398 0.0046322677
0.1885 0.1873856767 235.61925 44.1516726071 5.886889681 0.0041772657
0.189 0.1878767965 235.61925 44.267389878 5.9023186504 0.0036526772
0.1895 0.1883678693 235.61925 44.383096082 5.9177461443 0.0030915839
0.19 0.188858895 235.61925 44.4987911902 5.9331721587 0.0025257002
0.1905 0.1893498735 235.61925 44.6144751737 5.9485966898 0.0019833337
0.191 0.1898408046 235.61925 44.7301480036 5.9640197338 0.0014878016
0.1915 0.1903316883 235.61925 44.845809651 5.9794412868 0.0010563753
0.192 0.1908225244 235.61925 44.9614600869 5.9948613449 0.0006997838
0.1925 0.1913133128 235.61925 45.0770992824 6.0102799043 0.0004222589
0.193 0.1918040534 235.61925 45.1927272087 6.0256969612 0.0002220689
0.1935 0.192294746 235.61925 45.3083438368 6.0411125116 0.0000924514
0.194 0.1927853906 235.61925 45.4239491378 6.0565265517 0.000022834
0.1945 0.1932759869 235.61925 45.5395430828 6.0719390777 0.0000002189
0.195 0.193766535 235.61925 45.6551256429 6.0873500857 0.0000106007
0.1955 0.1942570346 235.61925 45.7706967893 6.1027595719 0.0000402988
0.196 0.1947474856 235.61925 45.886256493 6.1181675324 0.0000771007
0.1965 0.1952378879 235.61925 46.0018047251 6.1335739633 0.0001111342
0.197 0.1957282415 235.61925 46.1173414567 6.1489788609 0.00013542
0.1975 0.1962185461 235.61925 46.2328666591 6.1643822212 0.0001460844
0.198 0.1967088016 235.61925 46.3483803032 6.1797840404 0.0001422432
0.1985 0.197199008 235.61925 46.4638823602 6.1951843147 0.0001255989
0.199 0.197689165 235.61925 46.5793728012 6.2105830402 0.0000998132
0.1995 0.1981792727 235.61925 46.6948515974 6.225980213 0.0000697361
0.2 0.1986693308 235.61925 46.8103187199 6.2413758293 0.0000405802
0.2005 0.1991593392 235.61925 46.9257741398 6.2567698853 0.0000171299
0.201 0.1996492979 235.61925 47.0412178283 6.2721623771 0.0000030674
0.2015 0.2001392066 235.61925 47.1566497565 6.2875533009 0.0000004821
0.202 0.2006290653 235.61925 47.2720698955 6.3029426527 0.0000096104
0.2025 0.2011188738 235.61925 47.3874782165 6.3183304289 0.0000288281
0.203 0.2016086321 235.61925 47.5028746906 6.3337166254 0.0000548913
0.2035 0.20209834 235.61925 47.618259289 6.3491012385 0.0000833983
0.204 0.2025879973 235.61925 47.7336319828 6.3644842644 0.0001094203
0.2045 0.203077604 235.61925 47.8489927432 6.3798656991 0.0001282342
0.205 0.2035671599 235.61925 47.9643415414 6.3952455389 0.0001360774
0.2055 0.2040566649 235.61925 48.0796783485 6.4106237798 0.0001308419
0.206 0.2045461189 235.61925 48.1950031357 6.4260004181 0.000112629
0.2065 0.2050355218 235.61925 48.3103158741 6.4413754499 0.0000840972
0.207 0.2055248734 235.61925 48.4256165349 6.4567488713 0.000050553
0.2075 0.2060141737 235.61925 48.5409050894 6.4721206786 0.0000197578
0.208 0.2065034224 235.61925 48.6561815086 6.4874908678 0.0000014493
0.2085 0.2069926195 235.61925 48.7714457637 6.5028594352 0.0000066034
0.209 0.2074817649 235.61925 48.886697826 6.5182263768 0.0000464866
0.2095 0.2079708584 235.61925 49.0019376667 6.5335916889 0.0001315737
0.21 0.2084598998 235.61925 49.1171652568 6.5489553676 0.0002704175
0.2105 0.2089488892 235.61925 49.2323805677 6.564317409 0.000468572
0.211 0.2094378264 235.61925 49.3475835704 6.5796778094 0.0007276686
0.2115 0.2099267112 235.61925 49.4627742363 6.5950365648 0.0010447382
0.212 0.2104155435 235.61925 49.5779525365 6.6103936715 0.001411859
0.2125 0.2109043231 235.61925 49.6931184422 6.6257491256 0.0018161862
0.213 0.2113930501 235.61925 49.8082719246 6.6411029233 0.0022403915
0.2135 0.2118817242 235.61925 49.9234129549 6.6564550607 0.0026635103
0.214 0.2123703454 235.61925 50.0385415044 6.6718055339 0.0030621603
0.2145 0.2128589135 235.61925 50.1536575442 6.6871543392 0.0034120639
0.215 0.2133474283 235.61925 50.2687610457 6.7025014728 0.0036897795
0.2155 0.2138358898 235.61925 50.3838519799 6.7178469307 0.0038745227
0.216 0.2143242979 235.61925 50.4989303182 6.7331907091 0.0039499471
0.2165 0.2148126523 235.61925 50.6139960317 6.7485328042 0.0039057469
0.217 0.2153009531 235.61925 50.7290490918 6.7638732122 0.00373895
0.2175 0.2157892 235.61925 50.8440894696 6.7792119293 0.0034547857
0.218 0.216277393 235.61925 50.9591171363 6.7945489515 0.0030670334
0.2185 0.2167655319 235.61925 51.0741320633 6.8098842751 0.0025977956
0.219 0.2172536167 235.61925 51.1891342218 6.8252178962 0.0020766704
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THETA (rad)
INTENSITY
DIFFRACTION AND INTERFERENCE

Interference and Diffraction

Pre-Lab: Interference and Diffraction

Name: Section:

1. What is the difference betweeninterferenceanddiffraction?

2. Under what conditions is diffraction observed?

3. Under what conditions is interference observed?

4. In the two-slit experiment, do you expect to observe interference diffrac- tion or both?

5. Briefly summarize the procedures you will follow in this lab. Write one or two sentences for each activity.

6. List any part (or parts) of the lab that you think may sufferfrom non-trivial experimental error, or may otherwise cause you trouble. Howmight this affect your results?

Lab 11

Interferen e and Di�ra tion

Warning: Do not look into laser with remaining eye.

Unknown

Objectives

• To investigate evidence for the wave nature of light.

• To understand the phenomena of diffraction and interference using laser light and varying slit patterns.

Overview

Diffraction

When coherent light, for example light from a laser, passes through a small hole or slit whose opening, of widtha, is smaller than the wavelength of light,λ , (a≤ λ ) adiffraction patternis observed. Diffraction arises when light passes through a single slit. If the diffraction pattern is projected onto ascreen a distanceD away, we can observe that the diffraction pattern consists of a series of bright spots (maxima) and dark spots (minima), see the figure below.The location of the first minimum in the diffraction pattern for a narrow slitcan be obtained from the relationship

asinα = λ (minima) , (11.1)

whereα is the angular separation between the center of the central maximum and the first minimum.

The angleα can be derived, for small angles, from the following relationship between the distance to the screen from the slit,D, and the distance on the screen

147

148 Interference and Diffraction

from the center of the central maximum to the first minimum,y:

sinα = y D

. (11.2)

We can now combine Equations (11.1) and (11.2):

λ = a y D

. (11.3)

✛ ✲D

Coherent Light

y

Intensity

α

λ

✻❄a

Diffraction Pattern

m= 1

m= 2

m= 1

m= 2

Slit Screen

Interference

If the coherent light is now shone onto two slits (instead of one slit), each slit will have its own diffraction pattern; however, if the slitsare closely spaced these patterns will overlap. The introduction of the second slit produces an new pattern known asinterference, see the figure below. The interference pattern occurs within the diffraction pattern. The separation of the maxima in the interference pattern can be described by the equation:

dsinθ = mλ (maxima) , (11.4)

whered is the slit separation in the same units as wavelength,θ = angular posi- tion of the mth maximum,m= 0,1,2,3, . . ., andλ is wavelength of the light. For

Interference and Diffraction 149

small angles we can use the approximation given previously in Equation (11.2). Thus,

λ = x m

d D

, (11.5)

wherex is the distance between maxima, andm is the order number.

✛ ✲D

Coherent Light

x

Intensity

λ

d

Interference Pattern

m= 0

m= 1

m= 1

Slit Screen

For this lab, you will need:

• Laser with stand

• Meter stick

• Ruler

• Selection of slit slides

• Mounting block

• Computer

150 Interference and Diffraction

Activity 1.1 Diffraction from a Single Slit

1. Find the slide with the single slits and place it in the woodblock. Place the block and slide about 10 cm from the front of the laser. Thelaser and slide should be at one end of the table opposite the screen.

2. Turn the laser on.CAUTION: Never look directly into the laser or allow the reflected light to enter your eyes!Make the proper adjustments so that the beam passes through the slit (use single slit C). Make sure you get a good pattern on the screen. Record the value of the slit width, a, that is indicated on the slide.

3. Make a sketch of the intensity pattern.

4. Measure the distance across the central maximum from the minima on either side. To gety, as shown in the first figure, divide your measurement by 2.

5. Determine the wavelength of the laser using Equation (11.3 after measur- ing the distance from the slide to the screen (this distance should be about 1 meter). Compare this to the actual wavelength of 6.328×10−7 meters by giving the percent difference.

6. Repeat the experiment to determine the wavelength with single slit D and compute your percent error. Which measurement has the smaller error?

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7. Discuss how varying the slit width affects the diffraction pattern.

8. The diffraction pattern was discussed in terms of coherent light passing through a single slit. What is coherent light?

Activity 1.2 Interference and Diffraction

1. Find the slide with the double slits and place it in the woodblock, using the same basic setup used in the previous activity.

2. Turn the laser on.CAUTION: Never look directly into the laser or allow the reflected light to enter your eyes!Make the proper adjustments so that the beam passes through the double slits labeled C. Record the value ofd. Make sure you get a good pattern on the screen.

3. Make a sketch of the intensity pattern.

4. On your sketch identify and label the central bright fringe m= 0, then label the first bright fringe on either side ofm= 0 asm= 1, etc. Measure the distance from the centerm = 0 to the center of one of the fringes labeledm= 1, this value isx as shown in the second figure. Place your

152 Interference and Diffraction

measurement on the sketch. The interference maxima should be within the central maximum of the diffraction pattern.

5. Form= 1 determine the wavelength of the laser after measuring the dis- tance from the slide to the screen (this distance should be about 1 me- ter). Use Equation (11.5). Compare this to the actual wavelength of 6.328× 10−7 meters by giving the percent difference. (Note, an addi- tional way to measure the separation between the interference maxima is to measure the distance across several interference fringes and then divide by the number of fringes.)

6. How does your measurement of the laser’s wavelength compare between this activity and the previous activity? Do they agree?

7. Discuss the effect varying the slit spacing affects the observed interference and diffraction pattern. (Note that here the slit widtha does not change.)

8. What happens if you cover one of the slits in the double slitand shine the laser on the other? Compare the observed pattern for a singleslit to the one that you got when both slits were illuminated. (For example compare single slit C to double slit C.)

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Activity 1.3 Interference Pattern from a Thin Wire

You can also get an interference pattern if a thin wire is illuminated with a laser beam. The wire acts as the slit space between two infinitely wide slits. The large pattern you will see on the screen is the interference pattern.

1. Take the cut-out index card with the fine wire and illuminate it with the laser. The screen should be about 1 meter away as in the previous exper- iments. On the screen measure the distancex from the central maximum (m= 0) to the first minimum (m= 1). Now calculate the hair diameter,d, by rearranging Equation (11.5).

2. Is your answer reasonable? Although it can vary, the wire is approximately 0.1 mm thick.

Activity 1.4 Interference from a CD

By shining the laser on a CD, you will observe an interferencepattern. Using the interference pattern we can can determine the spacing between adjacent tracks of information on the CD. In order to do this experiment we will have to change the experimental setup, see the figure below.

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Interference from a CD

Screen

Laser

CD

D✛ ✲

x ✻

❄m= 1

1. Place the CD in the holder approximately 50 cm from the laser so that the CD reflects the laser light back into the laser to ensure the CDis perpen- dicular to the beam. The reflected beam ism= 0. Adjust the height of the laser so that it is at the height of the center of the CD.

2. Place the viewing screen so that the reflectedm= 0 beam is just touching the edge of the screen. Also make sure that the screen is perpendicular to the beam and parallel to the CD.

3. Now, measurex from the edge of the screen (m= 0) to them= 1 interfer- ence fringe (this should be more than 5 cm, you want to measurethe larger pattern, there may be an additional smaller pattern). You should also mea- sure the distanceD from the screen to the CD. Solve Equation (11.5) for d and calculate the spacing between tracks on the CD.

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4. How would you expect the track spacing on DVD’s and Blu-Ray’s to dif- fer? Will it be the same or different? If you are feeling ambitious you can try to repeat your measurement on a DVD (or Blu-Ray) and verify your hypothesis.

Activity 1.5 A Double Slit Simulation

The diffraction and interference intensity for a double slit can be quantified and there is an equation that describes the intensity:

I = I0 α2

cos2β sin2 α ,

whereI0 is the initial intensity, and

β = πd λ

sinθ α = πa λ

sinθ ,

whereβ represents interference andα represents diffraction. A spreadsheet has been set up to model the two slit pattern andis called

2slit.xls. Open Excel and load the spreadsheet program. You will notice that it has been set up for you. You will also notice that only half of the pattern is shown since it is symmetric with respect to the angleθ (in radians).

1. Leaving all other parameters the same, try changing the value for the wave- length (under the heading Lambda) from 4×10−7 m to 3×10−7 m and describe the change in the interference pattern and the change in the loca- tion of the first minimum in the diffraction pattern.

2. Increase the wavelength to 5×10−7 m and answer the same questions.

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3. Set the wavelength to 4× 10−7 m and change the slit spacingd from 3×10−5 m to 2×10−5 m. Repeat for 4×10−5 m. Describe the results in terms of the change in the interference pattern and the change in the diffraction pattern.

4. Set the slit spacing to 3× 10−5 m and change the slit opening sizea to 3×10−6 m. Repeat for 5×10−6 m. Describe the results in terms of the change in the interference pattern and the change in the diffraction pattern.

5. What would the pattern look like if the slit openings were very narrow?