W IHI”llllHlllllltlllllllllilfill 1|H1|||||||lMIIHHIHW 1 312 293 017711 TY 4.4M -,H/'~'\' h 1 1.1-.11 \UY'v—h ”O. ‘-_‘ \ . v «1‘ 5.4- - Q t - 77' I JLdL -‘.~ ”‘91 DInSbi A ~‘54- H .J 'T &J‘huu m "f: L ‘ .N - ‘1 1 O- -cC1ellan Elwin *ril V v G C v. V. r. as HI. IOI‘ 8 +0 1 C2118 - ‘.1 PW‘ A ./-A- ‘ A 'ence n U +'. 058 agree of \ .TV 4.5 71/ 0/. ITTRODU CTIOE A; - Phlk'l‘ 3 CALIFELKTI’JI? =7 ’3'“ PVC qu- "fl' am qT‘u‘ .-‘_J‘£D “"1 11.3 I. J. TNT V u '“'."T A“ LJ'DL-JD.._..' 2': —-¢ 113 w- v-v-rp- .l-$-; *5 .‘ .'."\..1 1L-L-.-i-‘.0 1.3 A" 717-. 1+: . .p.J—~ A::LIIT. an Ts‘w'fi" :‘Q ~mTfi"v ¢Jln4 Jfk‘q.-. T' T ’\“"‘"‘1-C '1 :3- :7} f) .3- () U\ \L) \J! IFTRSDTCTISN In the years of 181 l5— 18 resnel prooounded tc tle French Academv of Sciences his theorv of diffraction snooorted bv such .J 3 3 - i .1 conclusive experimental evidence that the intervening years have resulted in mere mathematical eloocrati n of his fundamental con- cepts and out litt]-e meantitative investigation of his experimental evidence.1 Beco-Jse of the non—existence cf aooaratus capable of measuring the districution of the enery; in the pa terns which he studied, Fresnel was linitec to a *.ianl OJs ervotion of the location ‘ ... of the maxina and minima. The only qualitative meosuren nts to which any reference has been found were reported by Lvmnn of Harvard University in l?29.2 His method consisted of photo gr .ohin: a straig ht e61; difiraction pattern and aeosiring it with a micro— photometer. The exposure-density curve of the photographic plate was :nefie at the same time and :rcm it the microphotoneter trace was corrected to give the ectoaJl distriOJtion of the light intensity. He records only the intensity ratios of succeeding maxina, which check tle theoretical values within his estimated probable error Of 11700 measurenent of very laint light Department of the Michigan State College during the summer of 1937, it was thought wortn*nile to attempt a direct measurement of the ener distribution throughout a diffraction patt eir For tni C) 'w/ q purpose the diffraction pattern due to a single narrow slit was chosen. In the sirgle slit pattern used the int deity of illumina- tion at the first minimum is about 2 x 10"5 times toe intensity of the first minimum of a straight ed*e pattt rn produced bv the same optical system. A tyiical strai rt edxe pattzrn is shown in Fig. l. Fig. l. Pno f a single narrow slit ion pattern. “'4-" Pi'li’hlicb The pattern vas produced by a single narrow slit, approxi— mately 0.02500enti21eters wide, .Jnd we measured at a distance of 204.0 f .5 ens. iron the slit. There is considerable possible error in the width of the slit given because, due to a multiplicity of arms and levers in its construction, there was an unknown amount of springing when it was clamped down on the sheet of celluloid .nicli was used for a thickness gauge. A more accurate value was q calculated from o serve eo data The slit was fastened at one end of a light tight wooden box, two meters long, and finisLed a dull black inside. At the other end was mounted the ap,aratus for measurinw the lighti intensitv. An optical d_iarra n is shown in Fig. 2. Unfortunately there was no source of monochromatic light available oi permit the measu. lent s to he naee and perforce a tunfisten lamp was 1 -. ° ”HM.-. v- -. ~ no ‘Y and Die ails (rxnvzilnters «pl air .l- -F—" used. Corninf filters G3 respectively) were used to isolate a portion of the continuous spec— trum emitted.by the tan sten. The lamp was a Testin house 100 watt ZJIO jection la 9 of the ri on n filament variet The ribbon, 0.001 inches thick accord‘ng to the manufacturers, has turned dzewis e to the slit to apiroxinate a point source, or in this case a line source and was 102.0 i .4 cos. from the diffracting slit. The 1L; t sensitive eleient of the a) Jarat as was a Visi— tron tyge 53—AV vacanm photoelectric cell. This tyne of cell is in COddOH commercial ase ant 11as well known characteristics. It con— sists of a cesiun coated seni-circi a. er slate ¥/3 inch in Ciameter and 1 inch long. A small concentric wire W;en nade positive with I'SS ’Lj ecx to the plate, collects tfle ghotoelectrons ehitted by the cesium. Immediately in front of tse cell was a slit, 2.5 by 08 c 8., parallel to the dizfracting slit. The ocsit ~~ ‘\ L‘. -L - . ‘f‘ “a 1" 1 rw‘ A . . ~v ,-‘- . 4'~‘, . SuCL that the 11 it comin. tL“OJxfl the slit alwa s nit on the sen81- f 4 \._.4 “.1 V q ‘ tive surface. A General Electric type FP—5+ electrometer tare was congled directly to the o1 otoelectric cell and was used for therei— onic anolification of the current flowing through the photoelectric cell. This tuce was placed with the photoeleo tric cell in a copper box. The whole was mounted on a movable b d in such a fashion that the rotation of a screw would move the lifht gathering systen across the pattern in a direction perpeneic lar to the ootic axis and also N dc 2.95;, ._>...:.> a0» «Emacs: 02¢ in... .p 3m .35 5.5.“. “.25 J-‘. £1". ‘ n I \J f". Ditch .5 1‘88“ J—x b-.- N q 11’]. 11105188 The for ville: TL OS. 4...:4) p' . .n T, J. . L: are V6 1 ri 1" 1e e.. ccounts f C) \_1 time c ‘ -L w . g ‘ whlc; measure to t 111.1111 k cal 41 f. “ (3.3 u e. I‘ ‘1" . v’ 3.x l S 1‘. L, x U-.[. ‘ .. -— , ‘ 1 U , 1. e cell. cell, were a t‘ I L. e; u. I‘r O- . \.L L/ U L; — V\ I“ J‘ ‘ 1 .\ J. ‘ ‘~) 4- Cr 7.71 l 3,; .1 e 1.1 U use I1 q , L8 q 4. U LJ ‘« -18 CE); .‘ chlori LJ .1. :1— .1. U st— of rvitv 1c reel I a- q q " 8 Huh {if/‘1'. T CZGCI‘EBSG ‘L %m ‘i“. . O q U. 08 . T 170 1 he t Lu‘ue I la ~ - 1 t n -o- l - ‘W 617 hi: 0;: \4 g-TI’ S O U I‘ 4, ext e: *1 ”L o tLe filament, a e l J- .Le ce cnarge r q ‘ L; .41.. an .L ”JP. 9 and t 4.1.. cu. S TIT—5.8 :38 C ‘ ‘I (5 U 3‘ 14- 31 O 4-31 U4.( ~ - l with and the c {rid ctec m4- 4.1.U 831318. ul- 1e p ube arc Y * urOl 3e t e e 1e m .L U3; 7 il t q .1 4118 u— q e COIl 1n q W A 1 '7. C. 1 8. es of t A: cut :88 a low ‘a to CL 4— ~ w ‘51“. Q 4. U ea la effect of t ”l I ’ance between t ca cecr of l a ‘61 oter.’ 3 I. the negative .3 F. JTU .a A C ._.._ w ;. Nix rr ~\u .1; OD S .1* :1. NLA V. r ‘1 r‘ w‘ .L-; h. J 1' .5 fl ON 8 C' 111']? 81117 fl in t‘ S r 1‘. h 10 ”avior W \J .4 \J..- .1. . fin eta (N g a *8 W L_.. ectr m2 9 —~ 1 E} . r -.\i t e filament). U‘. +3 V} sA ‘1 “r0 .1. ed .9. UL) .1. b 3.: S egi ‘ _l h‘ L 1 expl ine\ electro 1 0 q _ “ ~ 0. .-‘ a-.. _.I 7' , ’~ 4‘_ fl 15+ by Dairicge and Brown,3 Wuo, aoaptin, a CllCth CEVSIOJGQ c; bollel, have built the tube into a sort of a hgeetstone briqge Circuit, the 8888-11] fJu C.) H U) {2, F ’JI C) 5. _ * 93 H 2".) U1 I D U 3 H H '11 H. . .0 \JJ . v. - -4. .0 3 4. ' . 3-109198 334.9 :- 8. '.'J-l€E‘.bt4GO-'€ S m x q : 3 z 1. , : 4L ,3 .e—-_ w :- FluOVC-‘é, a C--c'3..-1j 151 ti1€ '_-I’-LC«. bias 03.9.1330?» t--€ 2083.81.89-08 O ouebe two c 4-2 -+'--." ' A ., ‘ 4 -- x - I” '3 .- :«w 3-. eleeents or tee t-oe 1n optoeltle se es tuis lflcJLEHCihb the q "~. ' ,. , 'n .c‘ 1- r. ' ' -"-.. .0 .z.‘ .: _. ..- ., -_ ‘ 2...; ; - crioée. Some loco Oi the cenSlthltg oi U is S~S e3 may ce cotarnec l 1 .9 . a. , .4. 1- 3, n - .3- - 4.: 1.: .- .m- .. .- «4.3 .:~ -rom tee fact tang a C3en3e or 5rd 10 85bifll or one tgc-sa CU c- - 4. - .. , . ., , -1- A- , j .9 4- ; .D -.. .. . 4. .. \ ° .' a volt 3zwe a L01Vflh©fl€bvl cc-lec.rcn o3 aggrox_uately Fee $111;— 123. -, '3- ‘ ‘1 ‘ . '. r-l‘ —.. . ‘ r 1‘ an 7" ' "W V .1 . -' ‘ .neuer arc ciyrrcsgoxus to a clan:e in :fic ctr €43 of c x lo anperes. A grid voltage change, howeV.er, is not the or.7-v vari ble whicli will u:q::alance t e bridge. Any variation in fila3'1ert c rrer t ' - .L- p, 4-1. V” .~ -, 1, "_ - - .4. .L."_. ‘ n”- 1 ~_ , W111 dist3ic bge two or; owes ago dfiSCU the calexce. Tre 13;):rfec ‘l ”'1‘ . .C' 1 _‘, ‘l “‘ IN fit. '1’“ «--\';- ,. -, -: + _‘ fif‘.‘ ie3llaticn cl all col on soeres o- .ilemelt cover le: to the -inal ‘ 4-4.-- " .- '. . “ . .- ..:.' . .c- ”f‘ 7- . 1 ,__ .,,.. :9 aoopt-»A or a Series garellel coocrnetion or ;; cry ells arreujec -~ ,. r) .. .L. - "I..- - 4.1-' .4,‘...°,-... 4.‘-.. A. ‘ _ J. .... ‘ .- '- '4. to 3ite l; YOlbn. even ung COJwfinmblUfl coilo not mdlnbalh lbs 4- . '-.. , 4- 4r ,: 4— - ‘ . .t-, c '7. ° “I ' ~ - Uvrfllmal voltage at txe mowest cirrent crola or ;D mllLanIEIQS. T“ 'L“ ~.~ T“ +7. ' s 1—n , '5 q:- p. -. 1' '9»; —. LL -J. (. :LlO .2..th O... hull C14. OI) l s- LLU‘.’:’1 Jun 1.1.} o u. 1_ 1 0 1 .fl ' V _" ' 1 1' ., ".‘ .. ,.‘ . " -P --‘ r J— ‘ TAe cric,e crrc1rt lS afml"ahlf evagtco lar coMJe eating 1 ' ' . .. - .- 3, 4. 1‘1' ,, ' 4- 1" j-‘ w: .. j“ .1. ,f GJlSSlOH. Re-err; ., U0 file. 3, 1 till ce reao-ly seen teat vien there is no current llowinq through the giltafio~eter H O :U 0 ll i-i U) LG I) /\ I._..J V k_J o 'n 5 O ’D .C'J f5 0.. cl- S- (D where tn subscripts refer to the plate series res 0 space char'e grids erics resist ance re e.tivkly. Tle ef-ect of a Che :L3e of filagent current on the plate and soace charge firid curr— ents is shown in Table I and Fig. 5. Yow if the ”el'oioneter is to m .9“. :83 fizz-3" “>53: + 2.2-? c coo-n. uuZ<._.n.mmd . DEG Mug»; .C. 000.. gm muz<._.n_mmm ukdaa a. 000.0. ¢ .23 9:51... 92:. a. o. S a. o. m w .v N ‘ I ‘ ‘ ‘ I I I on.fl_ lb .01“. saw/110A ova-1 .Om..«. mZF It; mac-.53, 232m no 29.2245 . 60.». o 0 «U “J x 3 Mu / Q h“- T‘ 1. _ 1 QC ~51 5 77. 111. -9. 17.1.L ya. 1L —| O O O . O C 7- «o h..- C) 1/ ,3 2 71. 5 7. O 7.x «or. 1 1. fl. H...- i o Tu .L .‘....\...1 _(., I \1- “b-J... ‘ T T' “A a. {-i O T a O 2 :4 sec ,3 0 7| .00 MO .49 d3 d0 Q/ T- v z ‘3 R; o 6 o Cunnsur ~ Microampzms _ A L J _4 AL - - 74 76 73 so 82. 34 as as 90 FILAMENT .CuauN'r ~ Milliqmpcns Plate: 8 Vol‘l-s TYPE F P '54 Tune Gm! - -4 Vol’rs Space Gnd ~ 6 Volts FIG. 5 _7_ remain undisturbed by a variation in filament current (I “5 V U m 7—4 H L o - -:~. ..,-r-1 A .. -~- 4- ‘w p 4-7- - .1. . ~ :‘ ObLGI to lt73es re1a1n1n3 cons n7t, We mist naVe the co731tion 111— filled also that Thes e two cont: tions will Ie satisfied only at tint value of lila— ent Cirrent at wnicn the tangents to the curves in Fig. 5 have tFe same ratio as the ordinates. This will occur when the tan ents to the two c1rves intersect on tie If axis. Uith the operatin: data 3iven in F13. 5 the proper filament current vould be Slldubjy less than 80 mill ian3eres. Since the curves are relatively flat, for cLan es in filaient current no to e: oit on, gercent the curve and t lamen H- its tangent are essentially the sane and variations of f current up to ttis limit will have little effect upon the balanced circuit. This eli ninetes one of the most trc = leso7e difficzlties encountered in tne amplification of snail direct currents. In fact, with tne conve tions 1 aeolifier circuits the drift of the galvanoé meter was so raoic as to erev7nt any sttenqt to use the circuits enoer1.e mlly. It mith be noted here also that this compensation is effective for gradual changes viich occur in tie emissive charac— teristics of the filarent. TLis is of especial inoortance in pro- blems rhicn require a consirerable interval of time to elapse be— .1. tween the initial and firsl Year‘r s. The operation of the apoaratn: is easily seen from Fig. b. The filament current is determined by R1. R2 adjusts the poten 121 on the plate and on tLe sgace cherce 3:16. R3 and RP are tne two letternal arms of the bridge as 01 eV.io;slv nentioned. Rf is fc the ‘ n. I L ' , . . -- J-. ‘ .. -3 '7 .L. 4,.- . j .. 4 ‘ gnumse of a3Jl“ln5 the coricc. JotentLaL to ”3e 89809 nar3e -rie. - . - 7 - .___‘___. r’. \ I1. u—o‘ \- ‘H -L -7 . ' ' - . 'L - .1.“ .'7 '1 ‘fi . 7‘1 'L "‘5 V. Y : ' R3 centrols tn, sensit1v1tj o1 tne galvamonete1. R was 1or tne purpose ofa 731177111> a fixed bias to tne control out was not used. R5 is used to set the voltage across tn potentiometer to the proper voltage to make it direct reading in volts. To set the aoiarztus in ooeration the constants ar set at their apgroxi.: “be vs lies (F13. 6). For this information and much excellent advice, credit must be siven to a very thorough paper on thermionic anflil fier rs :v fiacDonald.5 After being allowed an hour or so of war11n3 up to eraCle the temperature distribution in the FP—54 to reach a steady state tne apparatus is ready for adjust— ment. For tne preli117~rf adjnms 1ents the 331V?" W1et r is reolaced ‘~--v cf- by a microanneter. Firs ED is set for zero current through th meter. The filament current is than varied.sligltly by means of R1, whicn will incalance the system unless, as is very seldom the one , H) the system happens to be adjusted to ful ill the conditions outlined previously for the compensation of the balance with respect to the filament curre ent changes. The circuit is rebalanced by another ad— justment of RD' This process is repeated again and adai until a value for R9 and R1 is four 1d for which the circuit is p.19 arced and remains that way even for slig ht variations of R1. The _ lvaioueter is then returned to the circuit and a final adiustment of the C )1 system is ma e. The circuit will now be sensitive onlv to variation; the potential on the control grid and is ready for operation. In the grid circuit the photoelectric cell, a small battery, and the potentiometer are placed in series and connected to th 3rid and ;round or filament. Preliminary work was done with . .4 1-7. . a conventional nirn res1scance, 10 L ones or 3reater, cornectee © .0; S H3—23 90 which has a specified sensitivity of 10-11 amperes oer millimeter at a scale distance of one meter. The mechaiiice 1 se siti ity of the instrumen was so great that it yes necessary to mount it on a shelf attached directly to the heavy foundation.of the building in order to elinin— ate a constant mechanical vibration of such magnitude th at the scale 3 Could not be read. Residual vibrations were further dumped by C setting the It 111 anoueter on a heavy iron disc supported by sponge rubber pads. The solidity of this mounting made possible a rather long optical arn, about four meters, whiCh was the weriI 1 length possible in the roozn. At this distance a change in potential Of one thousandth of a volt on the con. trol grid caused a deflection of about one millineter on the galvanoueter scale which was angle to permit the potentiometer to be read to tho sandths of a volt. The -11- l + ~ r 9 4-3 -,-'.'11 m , —:—~,‘ m "2 - ~14- “s- 1.25 ht Source lor t-e Eu vauoheuei ins a 3 0.9. altohoulle bulb. An in ma e of its Iilament was forned on the mirror of g lens directly in I‘ont of the galvanometer formed, cv means reflected light, 'ri iz'na e of 1316? pro ecti on lens 3 table. A pointer was attached to the screen in such a way the l'ght from the ralvanoneter mirror cast a sharp p011 ntei w , of it. The operator's tas K was merely to keep the image of crossuhair on the pointer bv nanipulatin5 the potentiometer the photoelectric cell moved across the oattern. .1 Calibration Of The Photoelectric Cell and M ’10 ”'1‘.‘ . 1.18 ill ”w PIS (D sqiare law we .s a.)Ilied for caliorat a-\ )ti {3 O photoelectric cell and tie associated amplifier, An 0 t nn3.set up in front of the di1:rac iicknesses of typewritine paDer to mane it x...‘ - L d- t-‘J m D; Salvanoneter 0y a sin ;le lens wi'ch n s mountefi with the lad ll headlight housing eSQecially designed to eliminate stray light. A long focus of the and a cross—hair stretched across it, on a. translucent screen upon t-e ooerntin: while To inszre th at th 5falm. meter was operating near its maximum sensitivitv it was connected into a resistance network as Shem in Fig. 8‘. The deflection of. the l"'n01eter WES LL? 0 . _1 . ,° . wnicn amounts to a se 81 tivity of 1.07 X lO 1* aAQGTES HGT £1111- reter. This, because of the lon5 o cal art, anoxnts to but one fourtli the s1ecifieo sens itivit", but heinjouffi01ent it was not thou5ht worthvhile to tinker further with the delicate instrument. lifier q In of tne ench (‘1) , anion was opened to its full width where it had no effect. On the :3erch a li5ht source was placed. This consisted of an auto obile hesdla 1p ence sed in tvo use source and to w .0; >.:>:..nZUm duhu—ZOZ(>._(U to Pam—deao‘ds Anna 59.35.050.500 m: on»... 26.— .c. 000.02 .c. 000.0. God 31> a»... _ T - . _ ~12- I cut down its intens ity. This was wrapped wit a small area of about one two hundredth of a the source. Directly in front of this as ters as were used vith The source and lters were the optical bench. Positions of the source on 8.16 hence its intensity, vac t-en chanted an? a new set of readings made. Four overlapping sets of date were taken in order to cover tie necessary range of intensities. Thcsv data are recorfed in Table II They are plotted in Fig. 7. F101 this figure tue cou— oa re tive i oter isities of the sources were oota potentiometer reading inricates a oarticular tion on the cell it is equate nation produced by two of the sources 13 Fir. efi‘anen they produce equal potentiometer reedi ngs. By m ans of this Figure and the in— inamse square law the fClloTl“: TPZRtZOnSAlpS between tue inten81ties Fl) 0 the four sources can IIV= - I standing for intees1ty an: the Kauai the source as in Table III and Fig..9.. acieque. t e ure:-'1ents for the comparative mes. u CUt 1n order to JPVC an 100a of tie order of SOL'LICS were the light source for th e Potentiometer readings were 4.". . .1- Ulie 1:10 a a opaque tape except for q '1 ‘ . ‘- -'-.‘,. ‘ I‘V Sqra‘e lDCfl anion server gml.ced the same fil— taken for various The area of the source given intensity of illumina— sities of ill umi- for the number of 1 I’TiilCil we are was too 8) r e t t l e rmo n . my 5an 722 O C 72.56 5.8.8 :24 503 l 2,, .. .l 7.2 1. r3042 1n“. 2 2 0.70 do Yalhr l O O ”51.1; R t. l 2 75 5 :.,ru-n Rfiu- 732 722 2 2 2 2 2 l l 1 “H.“ “I!“ mm. o o o I o 0 o I o o o o o o o o o o u o o I e .1_ .r t 5 I O F. Th F P. .—.v.. Q“ A D u... A 7.. ”...“. T4 C «.1 .1 av V. 9 I . C S I Au 8 T. m _ n... C H C 1/ vb “0 r.” O . l L ”a a 8 2253/5 RE- 7 50 72/. 222537714 74 2 .-3 .. 3‘ t o o o o o o o o o o o o o o o o o _ mm 8 O 0/ O/ ((3 nu 0/7. O/Q/O af. 0221333272111 7.71/7. T F .1 T 00/013,027 (.0920v{ 07070;)? 202 71 O D 2 2 2151.44 2 2H 4 2 2 2 ..JZEfifirfir .414 1:“ "Li.“ 1}" ...... 0. P... e I t C n1 C «I B T. Tu .A C R h I O C n F n 4; C 10 A B a T 9 I .4. 13. 0472092 I 0582 I 0022. 32 970 a. a I O o o o o o I o o o o I o 0 C 8 8012.11. 0 3.5 20 40.2 dorm/flu 02:10. .11 e _L..,\.o 2 r30 8 .1420 e _ 2/o.(02.40 ta C 112 C 12 C 1112 O. C r .r H O S u u O O O «D S S [If ‘. Source IV 31413022 7 713/ 2 x0 1 C n) 930 ll. vain/.0 9:0 I O O 0 0 Of, A... , 740 91. C, o 16 l 2 2 7.132. O r371 S file/O PD _ 22/0/77, ‘ E.M.F. Dcvc'oPCd ~VoHs |.\ LO .. . \ . \ \ ....\ I \ " \ ‘2 ’ \K ii 20¢ 340 :00 32.0 330 400 «o 400 Dustuncc From Photo Cell ~Cm5, FIG. 9 -ll+~— Cu [,4 read on an ordinary illumination meter, an interne 'ate standard was necessary. For this purpose an ordinary candle was chosen. It gave an illumination of seven foot candles when ten cue. from y ~75 candles for the candle. This va.ue is subject to an error of about {J- ’3 U] *4 cf 3. O H) the illumination meter whi h corresponds to nteu 533 ll 4% due to deviations from the inverse square law at this distance because of the finite size of the ghotovcltaic cell of the meter and of the flame of the candle. Source I was then compared lVitl the candle ov means of a grease—soot photoneter with the following result: 11/15a = .75/1552 II = .035 CD. In order to take flll acvar ta e of sijri icant figures, assume Source I as .0050) C3. and from the reM tionships previ ouslv given: ll 0 Q L) n (3 3 0 U C II II]: = .0024? cp. IIII IIV = .01-?0 0}). 38ing these intensities and Table II the illunination on the cell for each rea ding of the )oten tionleter can be on lczla ted bv means of the equation: Illa lAnation = KI lu er ns/cn2 where K = I when d2 d is in cms. Fron which comes Tacle III. This table is plotted in Fig. 10. Yote that inasmuch as the pctentioneter was set to a rea ing of 0.100 volts at no illumi— nation, this value has been subtracted from the potentiometer readings of Table III before plotting. A large plot of this graph was us a W I - ‘h . ’ ~ * " u ed cs the calioration curve for conversion of octeutioneter A III E L Q. . . n... 'v? -b Tit 10'5th e 209 .... , I" . 1'- ,‘ r'1n- (vo 14.69.; Its) A 91,0 0. 9.4 .9/0 ,0... ,0 .92 0 0 27.2,... 019.90.97.19 L. Eu: , 0 0 AU 1.10 /3 7.790 .40 9.1.0.00 0 O... ”1.1 a...) .79.. n1. ..-.77 1 ll 2 2 2 2 2 22 .61.. 74 .... .4 9.9.720 4/4... .09: 0.1 11 10‘ L r J. 26.340079.) 0 1.9.5.390 .0. .38 7...”... O..4 0/1 2 l. 9.90.1.0 2 Z/Z/zo. ..9 O O O O O O O O 4.9.)... 0..) -- woo/n 12.919171-.3:31403 12w 1.11122227192545011L)?02/ 11.1192“. 00+ 0* O. .07“. . ... 29.52.23... .220 awn 9.0. x 02923 . 009 00.N . 0.0 0W . 0d . 0.. 22.22.53... 200.. 1AAAAA41 6‘. snoA ~ Baum-c3 swig mag J readings GO intensities in the analysis of the diif‘action pattern. The nearly logarithhic resionse of the auxilif ier at th higher in— tensities is notable.* This can is seen i” Fig. 10 Where the grid bias change was >lotted.alsc>613rinst the lo aritrn of the in ntensity' to facilitate an extra43olati on at the high ihtensity end of the curve . Xeasrrement of Diffraction Patierns '0‘ Br . iainar: u .sure ents revealed the usual arra-r of ’ J *7.) xperimental "huge.” The galvanometer would make frequent large and often permanent juhgs, there was a corstant drift of the zero point, and various minor perturbations were present. T: -e e ract causes of the dir fic Hlt es were never dete: ine d but their magnis tudes were reduced to a nearly ne ligi ole amount by a thorough shielding of the co Joner ts and careful solderinr of everv co3nec— tion possible. The remaining connections were carefully cleaned an made tight. The potentiometer and 5? l\ va:cmeter, only, were unshielded. ‘The potentiameter, beinw at ground potential, was placed outside of the shielded control box. The galvanometer roald nave been setter if shielded but by twisting the leads to it aid removing theh as far as practical from the operator, the cayeci tance *Attent .on has been called to a paver on tnis sucject u3ich has apgeared since this WO‘K was completed.0 T413 *"’e Of CierlU 15 shown theorectically to give a trul" Jp.aTthJlC response of plate k) current to illuhination of photoelectric cell under tile conditions that the ohmic cu rrer t in the grid cir01it is s.3a] 1 compared with the photoelectric 01r1 ert an d th..t t :1e load resistance of th plate circ1it is lar5e, on the order of one mefohm. Deviations from these two conditions an d. the fact that the plate current is maintained constant in a cridge circu it o3e1 ated as a nail instrument prevents the realization of this ideal condition. -17- changes due to notions of the operator had very Ml1ght effects. Needless to say, careful adjustment of the ba7_ance circ1it was a It was necessary to ncke a dezen measurements of the pattern before the difi‘ic.ilties were eli11n.ted sufficiently to give an acceptable set of measurements. The data for ore of the es rlier and the last two oat tern are tabulated in Table IV. They are listed as patterns I, II, and III respectively. These data are plotted in rattern I shows the erratic early be havior of the anrarat— us. T ere are n1merc1s discontinuities in the c rve and a marked tendency exists for the galvanom: her to reiain at erch reading rather tran follow the pattern. Tris was grotably due to a slight rubbing in the Calvanometer. Pattern II was taken v th the carria ;:e traveling in the OPJOSi 0e direction to its motion in Pattern I. The play in the screw is very not icaLJe in the disglacement cf the peaks. Pat tern II I is the one which ran used and is‘a smooth curve except for two points in the very low ranges vhich are obviously 0) errors. This yattern i plotted alone in Fig. 12 where it has been '5 plotted on both sides of its axis of symmetry although the data does not e: :tend h oeyond. tr e first maximum on one side. By means of t11.e calioration curves (FM .10) the data ior this curve have been tranSIRted into actual intersitv values an 'these values (which are given in the sixth column of Telle IV)have 'been alotte; in rig. -5. This figure gives the relative inter sities of the different portions of the cvrve in their true H1 tion as ineasured. Congarison of this figure with Fig. 12 revee IS the 2n erit an. .1— »; I r q. . n».-. fl 0 P. e .... C I C T. G I r. -.0 .1 +0 2!; o... 3 .1 C I ...-..“ .-. .u .Tu CQ/ 7. / _ S S n.. n w-“ 1!. o. O -M. ...M ...... T. “y. I T4 8 ....Q C a S +0 w... I 1!." run I 0 ..w“ I v... nu S 8.. n ... 0. .0 rr. P, «L ft ) r S C +0 .Tu 1:“ G 0 .fl V .1 Liu 0‘... at, +9 O. P a I / q S H e 8 .l a...“ 1 .C C a a a... C e ..l. ...o R tern I 'T' U a." I f r. e r' '\ 4L 1 fatter II 40 .4 A .lt . 100 2.000 3.000 My A]. 3 . 600 .100 00 3.700 7. , O QC _ 0/. _ w... nu C.) .42, 1* _ ...), 2 4.200 «1:..300 r ..., 2 a Au :2 2/ 4.500 3h. ‘1 0"“ m". _,, .177 -17.7 . .300 ~“00 1‘0! 13. rn/ a: \L. AJ 0/ ...u- rs, f‘ .JL‘LJW ‘L- f" ‘1 O J.- 'v' . 23.2 DOV. -L.) C I 800 5.000 5.100 V 7‘ 1 rs. .. 7)., «...; 00 F) "f 1 A . . ‘1 A. ..v 7/ .- f. 500 2 9‘7. .L~/ I .000 P!“ 223,- 1 i “171 :1 :1 S C a... n.“ e P. CC, +0 :1. t. ilk .... flv .-. .1 t C 0.. S a... C m... n 1!. ax. fix. I S E. t +0 .31 e «U L a . r J hes/2) le 1 '7 ‘. o -'V"" ‘.'...\_/ C "‘ r- 37 -- net-x f 17‘; l I I 1... ..u 8. .: r e t: +0 on m r . .n. .Tu +0 «C ...: T... ,1 II 7/ KO .100 5.700 .5 2 .3 0 7. _ 0/ “.../.— .300 5 .111 11. 7 73/ /O I 0.000 000 (w .... .....I an. «I1 AF‘,/ F'- 41k. 100 C 9'. Z2 KO ha “4 _2s . 200 / -‘\ V o 0 xi- "-9 A a 1. 7a J 0.300 7} /C (Q 92 :2 7) 5.400 4/). 7: 7/ ... .0 7. .. C} r.) \1. w- KC *3 71 MA/ 73/ .500 /O 3 7:3 ./0 7- 9/ a .1 I «I. 1..“ 0L . 311 .4 £377 \ 1 0.000 u q 7.. x0 .200 f) 1.0 .903 .300 /O 1.120 016 .1 .s. o .150 22%. :3, do .900 .950 /O 1.210 -I -._H :L o 1.27 f C) H. ‘0'- V —7-’. .. . " ~.._I' .1 -1 I .QQO II 1 fl. 1.‘ D j : Cites \ il’lg .050 fl 1. {1'9 7.000 7.100 {3 \J Scale R , I i I . '5‘ ._.‘ 7- H. a 1+ 1... _ D I"VIO .1..\’~ I f,‘_ O 1.3 ,2; .00 I! flu T... 4.) .500 7 - ‘ .‘O 'J/ .300 79 x»; /C fi/I AJ 73/ /O 7 l 7! ma —4- . L .200 7-750 7 9,. 7) (-1,. .4' .020 r? 900 0 7-950 A/\ \J /' .’. /\ ..., . 1w], .3 x Q 100 ~( u. 0"- \WI ‘- 0 r ‘v (V X'w‘.‘ 4-r1 9 I \5‘pAO‘i'L" :VQJ‘fif‘ (3 "‘ A»)! ¢K bL-h -1 1K I'- 3.; ,‘J U-’ U...L4~ 2' .L v -C\I - rJLLA - 1 J- ’ nu. .fi . ..- «... ’3‘ J- «1" I “108) 0_au.e L1“P.S/AM. 03100: 0; II -— q A—:) n .. '3‘ III 4 1) , 1 C 08) 09. ()9. ( 3‘1 011 _.__. _. _-_ --. ‘ 4--- —1- 81 \J L'e-L :1 II III 93 C- (D H '11 .168 I4 ()\ .100 If IAN I aoo ..-- 3. .. ....m I $3..-. A! -\\ w. 8 Z my 7 E H C m 4 ~_ J... ... .w E I lmv.“ 6 C & ,, n N m . /. .M n J m . 0\ D “W. I £00 4.00 ’ b b I ’ D b l’ ...m o. 9. a. 1. 6. 5. 4. 3. 2. 950)... moz.o I u 2.93% mm Bioizmboq b b 7.0 6.0 IQO 9.0 8.0 5:0 LB 3 L2 P W 9 8.7..m&4.r 7.. 0 ' O 4.0 DISTANCE ~ INCHES/Z I2 F10. (.5' O I" s E H c ..m . N u I R . . m n . - m I 110.1! p F. O m P p F b b! P 8 .I 5 t. 3 z N<3 «.370... 3923 I $323.2. FIG. l3 of an amplifier navinw the Characteristics of the one used over one 1 J. -avins a linear scale. Intensitfx ariations whic3.1 wozlc be unre— vealed 0y a linear an.;Jlifier stand out clearly in the measured pattern. The intensity curve (Fig. l}),hcwever, is the one wl ich must 0e co.n)ar so with the th .eoretica ml oatterr. A Comparison with Theoreti a1 Values Theory: Fresnel's theoretice l arfla 331s of a pattern of this type consists of integrating over the wave front to find the resultant amplitude at any particular point, takinr into consideration both amplitude and ghase of the contribution from ea ch (iffei ential area of the surface of the wave front. This cerivation, in part or |-}J Whole, can 09 found in any 0' the common textbooks of ph'sical optL%.' The roces s can be briefly saetcnev in a qualitativ manner. Imagine a cylindrical wave front, shown in cross—section in Fig. 14. Let this wave front be civiéed into a large number of vertical strips, decreasing in width as the éistance from the pole 0 increases in such a manner that the phase difference between -. 001 respon oing oarts of adjacent StIIQS is constan 1or the waves ’1 reaching the coint P from each point on the were front ac O 0 5—5 Huygen' s principle. The res31tant amplituoe at the point P is the vector sum of the oontrioltions of an.)litude from each of the small strips. If the width of these strips is diminished to the limit of zero, the x and y components of the amplitude at P fine to t*e wove s~rfece 0.2.x. M4... between 0 and S.are given by the Fresnel integrals meson him—alan— (So: 361.. anemm..umn..._oz 0.... 0452082? <<> H -- I i ix! (','- ('3 r—I (' . Cd ,1. j m L: * l. (x 1w. .4, (‘- (“- « c? <_ " r“. R C) O C3 C1 C.) O C) (1- C; (‘ C.- . O n c f.) or M O :1. l _) :1: 3.. w {\- ,4 ;\ - M P’ \o H ,—.+ m \t’) \ .) Q . ,.-~\ \ .J .. f‘~-~ [\- LC“. 0 :1" (.' (3 < ‘ C7- " C" H r! r—! C) ('1 C " (“s O C‘ C) o ‘\ r0. 0 : n \. :1) N \ r4 0.! H ( .1 : r1". H H C“ 0 : r—{ ‘40 fl :(\ o r in) C) O :J' - J N'\ f*"\ Cl! C) (x O C C" C > C “ (\J o o o o o o o o o O :1“ k0 C‘ C r“! l C\ F‘ ‘ C. ‘ '.,) l'\ :1“ r“! ’) II II CD ‘~ '. -‘J‘ r‘--- r-. 41‘ ‘0. [h C‘- ‘ 0*, i» C .1 (7“. I [\- ‘- ‘3 r—l '~ 'D -‘J‘ ’< '\ o o a o o O o o o . 1 H 0' rm :J- L(\ fo \ ) r- r (3 C) [D Ex (3 if. rm 0\ L0 N‘\ O ‘60 u" \ J :2; L: ‘. 0.: m. r! N O (\J .13- 0.1 {1. O C 1 a: ~ L g \ t i O O O C) C) (F KO r—x H C) ( 3 (.7: C C3 O C O 0 Ln 0 ll “ 3 O O (7' : 1.. O 71-3 H (3 x :1" (\J . .-—£ .52. J r» Ln (‘v to m C.) -1- r» rs . :1- h (in, TI-ff \ 1‘) C" N x (j '1 ’ (T) (5" ( ‘3‘ r1: H H t"! C) C O C C, (‘ O ‘30 .u' ‘x t) :\— r--— (\J O - 1* ‘~- 3 r1 \ .23‘ r‘. f 0 .—~! I\ W. \ 1 to C ‘- z.) 0 C n: .3- :4 :J' r‘ '\ r-: (“I ('3 (.17 (is ( C) it‘d a o o o o o o o o . ?{"\:3‘ L('\ 0 C". .'\ 1' ".‘ ‘. i‘» ' O f‘\~ 'f \ CT“ I" \ u n ("w r ~ $1.; C . r — :7\ .2-1’ 1—; r‘ c: :J- at : . ox to rm no i‘\- ’< 1:, g o o o o o o o 0 . r-i CU I" \ 411' ' fl ' ‘T‘x ‘4') r\— g. :4 J m H .H m’ 5?: to (7 Cu 13 O o: M ;=-a r\- Lf‘. an (“I C) r“ '1‘. :1: +3 :J' [( \ TC" r—". "I ‘\ O N- \ r" r-'. -1] ‘- r) a; W" L:\ J“. I“ \ C" ' O: O (1‘ (7“;- C O 4.) (C) - o O o o o a o o o o 5:: “H r—1 :4 1"! r-‘ H c: :1 CD F“ L(\| Lb. $4 "'1 (3 rr‘ {\— ’ r-{ 1"“: l(\ ‘: ~“. _ J ( ‘ ’) a) a) 0 Q \. ) m x ;' O l‘(‘\ (I ; ,--! O +3 (I) C) r—t ’.‘.E (R LC‘. \IJ) \ D r~~ , . 0 g 4.) o o o o o o o o o 0 Cd 513 H. +2 :14 m 03 -.—4 2;} (L O 1:\ O C O (' C1 In t‘..‘ O 0 C3 :1 ,a: (1" c: if". C) i_{\ C '; -. [\— CW 1 (5. O O O O O .—: m m 0. rm l - fr [—1 o . a o a o o o o o ~24b— l(\ \ I 1' T") H :3 (Tm \ I' \ k 0 l ( \ M m (\J O o\ m :i 5” CI (1 J r 0.5 [If a: L0 15‘» (“a w 0' . rm 0 r’ r s v - r-J o M cu cu m H (a C) 0 (T?) C) (D c: O O O O o O O I I 0 O 0 H n r? f c D C D (M O 0.! (i) O ,‘J‘ - J“ \ : ) :3: A”. N :f :1- 0 rm \ 2 r- ! rm ( a .r w :‘J‘ r» :1: [fl LI\ :3“ 0 Lu?“ W C ( D O :J- 120 rx k) Lf‘. -4 1-7: Mn N ("I .—: CU IN ‘\ .13“ :4“ L(\ \ f) :\— 11:.) \D O C“ l c \ WK r”. O -1!- C r» Ox [\- n r4 O L(\ u—i 7:: I“ -~ (.1 C -. H D H (1: Ln II\ C; U) ‘0]! (‘1 F C» t' . ( . r4 Ln ,Sd CD.) 0.! (\I H ‘- C 3 (_> (J (D (D CI Ln 0 o o o a o o o o o o O g—J. u C 3. ,J C) 1') r H L N \ : : .. (3’ r”. r» i M m H LI‘\ .+ ,4" [~— r t (f .-~t u \ [\— rr: \ I m .d- c : m. .~- (“ a r O r‘ F“: r! H r'! O C (3 C) O C ) C) O O O O O 0 I O O O N H H .N \ m f‘a.’ C} \I) I“. V“) r» (I: O (D ‘1'; 0.} f"‘\ I“ ‘\ -1." (“I I’(\ P~ 14‘,» O :1- :i' 4%“ N‘\ INN r—! C?- C) O C) O O O o o o o o o o o o o 0 1M Lo . O O :3“ H r! 0! I“ ' m [In N x w \ II I] :> C‘- L(\ O O C) O C) l.(\ C) O C) C) Jj' (.7\ ".A) F‘- \ 3‘ LCD ()\ - .4. I“ ‘\ (.‘J ,< :7, o o o a o o o o o o O H (\J N\ ;;f‘ :1- Ln \ (D P - F O s (D I'm N t’(\ C) I ". I‘f\ \ U f(\ (D\ (I: . o \O m .—-| ('3 r 4- O (5, CJ “:0 1;) m :3 c- m r\- a: \. I) .- CD O (W C) (' H r—‘I H r" 1"! 0 Ci ’ CI) 7' O C7 C.) o o o I o o a o o o o o H II ‘ I". cx r—1' \ i) n— r—-!. -‘3' \.:TD (D! CD: D [fl ,8! F ‘ 0 VD r-—! m H I? C " C OJ {\-- r~ (I: =0 \0 m C) [m [—3 O C‘ ( ~ (D ( I» H r! r-{ 1'! O C‘ C} (.3 O (.‘D O o O O O O O O O Q 0 0 no N r4. \ '3. C) K .3 N r~ .: 1- r\- o m n: o Q ‘t-'.‘ m v7.1 m m r-a :j- ~.« m l.(\ 1-4 43: :4 N‘x N \ 0.! r--! O C D C) C .' O Od'j‘ o o o o u o o o o g o m . u u 0 (.‘\ OJ \.’. ‘ l(\\ [{X r": ‘ (47 \ r\-. ‘ F) C) H“ CL rfl L(\ r\- CI- In C) t‘ I -' z" r< :> >- C , 44‘ m ‘50 [\- m Ln (:jr- L.(\ .-.;- rm 0 o a o O O O O 0 O o H m rm :r m l m \ «’D [\- -243... r- O Q r--! ‘I N t\— O 0.: r\_ r» ,:z «"~ NH \O :f u”) LICK c . m \_;__\ ("I t ‘ O rm Id 0 O o \ r~~ :J' 09' ( <5 0 c? L(\ Ad H H F“ (‘2 C C» O O C“ O C' l\. o o o o o o g o o o o O I! 0' (T, N C m J ..‘J' \ n O 1 ;. MN m] r. - #4 r! 3‘ C \ r 3 [IN (3“ O’ I. f‘ \ ("1‘ r—4 .7! (Ii 4- r" \ m C \ :1) a. I o (1‘ C n c' D (J I"! ['4 r-'. r4 C J C.) C .1 3' (’3 C .1 C C) tn 0 U: : CU U. ‘\ CD I" I. I '.‘\ r“ H, [x \- LC 1 rd Lf'x i\-- C‘ . \. xD m .a x \ r) 0‘0 N\ rm t~'\ r~'-. m H C': C) ("J O C 1. O N O 0 0 o 0 0 o a o o 0 Ln m . N I II II C.- O .. r—~! \(D LEN NR H O 0". r\—‘— x a :> C > H .;J- [x H U: \ 0*. r"! r“ ' \ . D r.“ O O O I O O 0 O O I O 0 H CU In :4‘ :j-I LC\ 11 "x \1) {\J ”xx-’9‘ f" \ O ( H F" x C?“ 71! ‘3 ' LIN (DJ H C O ‘(jO H CV3 PM C1! r“ x (_ 7 LQC' :CI’. [\- P‘ lf‘. (f ‘\ 1—: U“. r 1 C‘. C ' 'f\ r ‘i 550 w m cu 0.; H H C.) (D O o o O O ' O O O O o o O O o o o r-l 3 II . *9 C) (U {u m m . Lf\ m u H H C) 6“ #4 1f\ :4" rd H C»: r- - \ {.1 Ca; 0 Ii 1;: ‘. - C“: :J- :i- fix 0 x. 3 OJ C'- r ‘ Cd .3 CD H H H H C) C? (L O C? C3 C‘ o O O O . O . o o O O O H O [G (>0 O L(\ 1-3. ‘0 r»! l.’C\ I 1", L11 7-1:. 10 ‘~ 5 i H t. :‘x \. Q ‘: 3‘ If M 43‘ [\— O (\J m i" x N ‘\ r-rx m H C J O O C) O l_(‘\EO . O O o o o o O O 0 . CU N V N O l ' f‘\ N‘\ 3‘\ (‘M ("7‘4 12’" T"‘\ 1‘ C? I“ {\- Il ll :2 (7 cg: {x (1. :1“ (ix -3' r\— O -. -d' or O .11‘ It" \ U If \ I“ \ (.‘xj \ 1) OK P‘- ,< :> o o o o o o g 0 o o 0 r4 (“xi WK .12" "L lfl I_C\ \ "J O C‘ ‘IXD CD ‘ r!” \ "/3 :j- _- i- (LI \ 'D :4 I. F (j (T. ‘ : [TD ‘I a) ‘55.) 1' ’. i r“? C.‘ \.O f“ ‘\ a: O (7‘ P» (D H :1“ (‘x C“ I” C‘ ,—-: C\ A‘. {0‘ (\J 0.1 (\J ,4 (D (D C C.‘ C3 (L‘- O\ 0 ' 0 o o o 0 0 O a O H ll 0? (7- .-;1- \0 C3 \ a“; rm m 1:1 O F“ . " '1' A! h H O a m ‘51» -2“ -J‘ C: .5, HR \ I) :1: Ln LI\ n x C) m 01 O C . (D O a; H H r! H o O C» C?- CD 0 C) O I O O o 0 O C I O O l.':\\ ‘ "I‘\ ‘51? P- CU O 'f‘ .- \0 LG 9‘ \ i) '60, CD! 0 o at: m m {x OJ L? Lf\. \ r) J (3 1m 1’0 0 O“ m l‘”\ rm rm 0.? H D O C.- C) o O f‘( “ O C O 0 0 O O O o o o l’\- - II II (D :5“ CU P» ‘0 Lf\ N N ‘ f" H (7" o M l\_— m C l\- :3 r\- \ I.) x s;- ,< :9 p. C) :1- ‘CCD I’\- V.) :J‘ F‘“\ I\ H Cl C" . o o o o o o o o o o r-? CU I‘~-’”\ .Lj‘ .3“ lf‘\ \0 \ "D . ‘.| ,~ \i V ’- * J- . ~ '~ ,\ -( v -' -A J.-. ,V - 4- -- —- ‘~ of Fiw. lo. Teese COLSbRu s, r, the Vfl\€Lefl;b“S lcec tee taloes Correction for licth of Photo—ele*tric Cell 8 C The Cate of Table VI give tie actual tleoretical pattern. However, because of the finite width of the slit in front of the choto—electric cell, this pattern must be corrected before it is L 4-- Colon -.. ‘l 'Lf 4.“- a. .... .h 1 --,:~,r ‘_- - 2-; .. “.' -, coooaracle Wita the menSUIGQ eii_raction Cattein. Tris cor: I; \ is made by clotting the theoretical curve (Fig. l?) and determining from the area cheer the curve the difierence between the in at the center of the slit and the average intensity across the whole width of the slit. The corrections made are given in Table VII TABLE VII Distance Along Correction Corrected Patteri — ers. Ifit°“SitY _) ’\!\J~’ x) \5}\J I . IIKN H v1 HHHH o, o 4 O O , f3 .12. 0 .3s .254 o .01 .351 o .557 .503 o .205 .935_ +.oo: .otoe .0953 +.QO4 .0190 .762 +.cc3 .0133 .889 O .0433 1.016 o .0553 m: ,. -.. 4-..* ‘ .z. ....n:4—4 : 3.. 1. -. - 1-. is 59 COLLCCU‘C lnCC cities neeo cit to oe cat on tee same scale as tee measured intenSiticS to “e directlv comparable with them. Conversion To Sane Scale: If the measured and calculatefi patterns were identical P b P WIDTH OF CELL SLIT D D Ir I 1.0 :5 L4- :3» 3.2» 9:23 8 7. 6 .5. 33:23? .9 3.. z .. Kazmpz. 3.53335 DISTANCE ALONG pATTERN ~Cms, l7 F16. I . = _ x 4989. Iculc. .‘ n V, ' noqu-t It“ “75"‘3 ‘- -'[.‘ 7“ Jo ‘fi W-l‘yre up. 18 a: CO;;L)U( .- .. CUL -CU —O ——L t1\ 4-,. ° .4. wo‘o'ti ah I.) ,- r. a, 1" \wyfinr: Lie U120 l-.ue:.ol 1K0. ..CJVC Jeefl .AC~(.L- -..}.KI». ‘ ~. ' "t. v" a -' ‘I 4- -6 -‘-~ 4- .. of :c woild co...e iroi tize 1304.0 or t.e no is marina, since at th frequency range of the light are '1 1‘1‘ 4‘ ‘Y‘ .Js.L .. u}. on the meas ed curve was 01 d \ Uration curve, it will be H. ment made away from the maximum. s 0.1275 ems. The int~csities are (from Tao I.-..-‘.... = 3.3:) 3‘ 1'3": .H,_\,..‘Q. — rfi Icpllc. - 1. D From these values k = 5.00 x 10‘7. In th t7“. --e calculated intensities of Table VII h J "- TABLE VIII Distance Along Pattern From enter iches Gas. .000 .000 00?? 00%;? I“ .100 .554 .1'50 038:]. .203 .303 .250 .cBS 9": i 5: .k/J .VE‘Q' .900 .{CQ .;90 .309 OLI‘OTJ‘ 1.010 The disagreetent “etweei the oh 4.- J a minimum. from an different UthP in whicl The ieeal Ceternination intensities at their the corrections end the v v ' hometer, . . ~94— eAUrapolat to use one :il‘Bu :1: at 0.0?0 irches o - les Iv and VI): 7 e followinfi :3 __ 1“ ..-.. .z.‘ {Ive "‘11 08911 ' 1U]. S 13:13. r17 0 I 0110 Qk..- ..L wk-.. - \. u 4- “ . - Inuenslty - Y . .. .2 mm?“ S/Cm X 10 f! 1 . 4.. ‘ ~ enrollateo {cesarec H Q! q 0 ’4 O L: ok/O ., 1' ;.:0 f . _ n C) O 90 K: o "O 1—- -— \, £7700". M‘ol‘f‘o ' 5‘ HT: 2.70 2.:e ‘7'.— IA? 1 00;.) o - 4/ 'f‘ "‘ v11 r— o «0) O .1--j ca is on of patterns and is orooortionat el‘ L‘I '1) all, {.4 ...: ’D H *4- :3 Cf d .1 ”D '1‘ L: 32" FD J) The Cali crLtion cur‘e (Fi . 10) gas son what less accuracy . i 4. .... ' ..-. J. .C‘ . 4'3- ,» ' .I. ' ' - j; __ . .- 1... u. SISCGHU. Tiiebe 0170 3014.0 , 3.; 1.;...C;l ci-€ LJCDI‘QSC 18 3.1.1 C.iSC...ree..ei- - i 1. . - ' . ' .. - m '~ 4- . 1 1 .... .. ' , 4.. - Vfltfl tlie CJI‘VG Cf 10,0, 111?? --dfl? C's .J'- L" 18 CO 9. S 1'....J__L bra-.Sleflu C8- .c- .1- ' .9 Jr. P. v- ' ‘. -,. ..'- ' ...... ..4‘ 2. ‘4 -'- '1‘... z 4‘ .lec ulOn oi 01.9 3.1 tanotiete‘“ .. . Cons 1c er atria. ...)- t...e ms urlucx --on o- 4. .1.’.. . '.,..;- 4.1» . _ .. .- '- °.. “ J- 4.}. 4.1. ~-.- ' one CU;;‘1‘ L3 1;.0 on tne carve wo C l1l£.lC?.L€’ plat t..e curve 18 not \a.—. Mcownd ... .. ._ Calculotd 5r I» b b 4 3 2 ~55 um... o... 3923 ... 5322.2. .30 .40 130 :20 -,IO 0 .IO .10 DISTANCE FROM Camera or pATTERN ~ Incas-s .. .40 I8 FIG. in error '03r as mac; as by at an? point save tle ertre e val- he 0: H. \ 1' .4/‘9 l-. f“' . 4-. , " ~- -w - -" '0'? ‘ '3' :11. 1+ wnere tne entregolation la3 3138 a1 error o- as great as v. 4 7%. The applica.ion of the potentiometer in the circuit used calls for a flow of current whereas a potentiometer is ce.li:3rated for an d is123_7r ooeratcl with no current flowi fl in its external circuit. But in this case the current flowing, the photoelectric L Q current, is snaller than the lest anoint which would be ee ct Q. 0 cf e e in tn ordinary ir01it, and hence does not disturb the calibration of tle ootentio eter. Drift of the galvanoneter null point and transient de— flect ions wer e carefull3r “we: cized for in hot 11 tr e calibration and pattern me agirenents. In both cases the drift was reduced to a J nerli 3'iole ancint while anv transients were of small magnitude as evidenced by the few m: egalar points noted in Figs. 10 and 12. No record was taken of the line volts e, which of course would affect botn the calibration curve and the pattern. Ho wever, it was observed several times during tne eitper iznent and the fluctua— tions were barely er o.nn to cause rerce ptible motion of the needle, a fraction of a volt. Farthermore, readings were usually taken late at night when the line load was essentially constant. . J 01 included in the lirnt source necessitated numero s cssumptiors a: approximations, most of them rather small in cons ed“ence, Lat re— sulting in a considerable over all uncertainty. The first assumption -. 1: -..—,. +— -- - .- -. 4' ~ , reaarclnl tne tengeratiie o. tee filament, is o: Linkncwn ma nitude. The averane tencerature is 3mobat ly soneWnat less than .. . 3 A ._ r." . _ .. , .. - _ .. Tnis results in curve VI of F13. lo beinc 01storteo. Furtner ClS— tortion is introduced by the fact that the filters may not :ave e: :act 3 the transnission curves specified. Koreover, the distribu— tion of the total energy among the eight oitzerns cLosen ca: o.ot be cone With hi;: h grecisi on anc would be but an approximation at the best. However, this approximation is not so bad because the extrene we vel en 3ths in any one of the ei nt patterns differ from the central wavelength by only 29. flow in a Fresnel sin3le slit pattern th, first miniarn does not have zero intensity but the fact that the measured atte; n does have a very IOW'vnlue is an indication that the minizna of the eL ht oatterns are falling closely together and hence any one pattern resembles closely the resultant pattern, which means that the correction of sunnin3113) several representative oatterns institutes some degree of accuracy in the pattern. In fact, it can be seen irom Table VI tiiat the extiene pat terr s difier from as avera e oatt ern bv less than 10¢ and therefore the average nattern.should be correct well Wit in this limit. 1’ For the calculation of the W dth on the dif;* raction slit the determination of tile avera 3e weteleng 1 can be made with fair accuracy but the assumption that the minimum due to this avera e 3 *Wavelength will fall at the sal— ilnce as the average n*niu r1 must '7- Zhave some error. Because of the relative slooes on the two sides cof the minimum, the minimum of the oatt sin of the average navelen; twill probab-y lie slightly closer to the center of the pattern tie n truaziininum of the aver? 5e patter-. This can £8 qualitatively seen 03' inSPGCtion of Table VI. The Width of '1 . w ~1. . . 4--'- ..., t- of t-e slit Tweolavuern "01C 1e _1 tiwre to changes in the VfiOLL -70- I if in this oarticular case the widtn ‘ .D . ' 1 h o ‘ one Sal; as W108, :or ins , _ of the slit had been taken as the estimated value which was 23} fireater than the calculated value which was used in the calculation of the theoretical pattern. In the alcalatefi pattern of Fig. 13 1 -..L. a r ‘. O . - '_‘ fl :5. . __ J— ,- f‘ _‘ r" ... 'r' - 2 4— n.— I - ' ‘ o ‘ 4. £1 recrense iniiridtn or b.&3£flluuern o: aucrtu Dy delC” waniné into account the slight res;!-tant increase in the value or the xizaxm‘rn, brine the calculated and theoretical oatterns into coincidence O A 7 two curves. This de— cf U) O '-f (D H H O H O I y ~ 0 ”J within the remaining limi crease of five percent in width of vattern woulo be brought about 0 I 3) jhy an increase acout 2.55 in the slit width, but the slit width iis only calcglated to an accuracy of one part in 23 or 3.39 and the pattern as calculated is therefore in agreement with the measured pattern Within-the probable error of the calcrlations. rrors due to readinfi the sgiral range from 2 to 10 percent, oeuencinfi ugon the magnitude of the reading, the gross errors agpearing in the snall values where the greatest ciscrecdncv exists between the calculated and theoretical values. No correction was mace for the width of the filament of the source. This width of 0.0025 ens. is but a fraction of the a— V. ‘.- no“ 4-9:. ‘ n- ' 4' a 4. '_ u’u 0“ .o_- .‘ ‘. g 1 .\ : ‘_- I. . .ldtu or uge Slit in iront oi the cell. where the truth or the ;ll&— .4 anent caused a slight diffusness of the pattern the cell slit was ‘ ght that it would have picked UP Wide enough to rick up the same li Lad.the filanent been infinitely thin and tfis error is entirely negligible. :“J This exper iml ends to 1. For electric currents, where the oark to the ghotoelectric current, good ing the cell to the thermionic tu't e .hose resistance is a function ano the potential across its terniinals. has the advanta: lowest lllJJ‘TflulOn and at the range. Tne usual connection nas a and a oefinite practical upper limit The circuit used in this exneriment '\ J_ _ r— ... O ‘ acout 10 l? to 10 1“ angeres. “1 a «w . —1 5" I" ~ ‘0 A." 2. ,8]:le CpuSlLSldLth CU. U118 that the measured would indicate that for Optical chromatic light, the res ltc—rt 819“”, easily measured than calculated to the ‘7 4-,. - 4.2. - .- +~ 1,, )0 'Hlb-.ln brie 8&4 0.x. t--e culated Fresnel single 81 1t tl'u ‘.at they are identical this e"o rinent 1.18 1 1'1; ‘ Q aonochronatic light, the thermionic amplification of current or sults in the faS of the quc '98 of being Specially sensitive same tine more or for eIolified {BIOS-8.318 errors, it is superior to phenomena of same degree of patterns are would conclusions: ‘ ‘~ 4- q‘ll-l. r)—*O U0— \ A very St the cell is congarahle are obtained by connect— .a {x (a: "‘."t‘! ' ,3. “I ’r .A ic:‘-L U -1 a only-L l\/- ».ea {5 a.ntit" of incicent ligh This tvge of connection ti in the recicn of consicerahle fl ‘ I O O - less constant sensrtiVity a given set of components. apuears the calculated one. This this type using hetero— ‘istrioution can be more 8.0011... We“: ' two ETEJIS the measures and cal— similar. Before stating have to he repeateo rc Acknowledgement The write‘ wishes to exorcss his sincere appreciation to ‘ave freel‘r of his time and hel.rul advice, to Professor C. U. Chapman whose kindness mace this research possi— ole, and to Hr. George Chapman ior skillful mecharical assistance. West of the figures were drawn by Mr. G. R. Gamertsielder. i . 91"- . ci-nw *K', »‘.. _/.. 5— I T I ‘-"“vvr J1-- , :3 -3 {‘1‘— * -- U ersitv o 9“- i ‘n i . 4‘. 17 ‘J P ,.l +vV row a R ug- Yu— mut T.» ..7‘ one- T C B I .1 d C an. fl . I‘ll A ~o-~v- ‘ I ...-.5. ... . "I r - -&- on- . L a) \ I t r if ter— '1' 1930. w Of C 01‘ F RC b— L) l V |' d. 4.]. .1. '“7 O .C‘ l 19 *‘10 ...—L. ..L < —' b) 1937' ll "1 Tw'fi 7' orfl ..9‘ i ."Q \I O , h r \J— trac I/’\ ”9““” ~ E“ s .e1 -e C 4-- A. AL? 8 .t L Q. h- C I I r‘\ "" Y] L'- U -1 ., avl’] 0"" e A. 5Q“ \ --I Y 0 :J . US A A. 2 1‘} n , ,SJQ V‘ M — {Ml-1) . 5.5-- 77 ’3 LL~ , J Re 1"cnts ~u4..\'¢.. 4“ .\ U;-..o-L . *.’,- U...‘ l 18 .J. .1 Jet? " 1r) ”1 L,.( 11 k“, 04-". A 6 . . —..¢ H:— RUG 0. r’. ‘nq MATH. UB- IV LI RQRIES Txllfllfllinlllul i {mg m HICH ml 31