,las]s by ,hal ,hellman ,u4,s4 ,,atomic ,,en]gy ,,commission ,division ( ,te*nical ,in=mation ,und]/&+ ! ,atom ,s]ies ,,atomic ,,en]gy ,,commission ,,unit$ ,,/ates ,,( ,,am]ica ,! ,und]/&+ ! ,atom ,s]ies ,nucle> en]gy is play+ a vital role 9 ! life ( e man1 woman1 & *ild 9 ! ,unit$ ,/ates today4 ,9 ! ye>s ahead x w affect increas+ly all ! peoples ( ! e>?4 ,x is ess5tial t all ,am]icans ga9 an und]/&+ ( ?is vital =ce if !y are to dis*>ge ?\ghtfully _! responsibilities z citiz5s & if !y are to realize fully ! myriad b5efits t nucle> en]gy (f]s !m4 ,! ,unit$ ,/ates ,atomic ,en]gy ,commission provides ?is booklet to help y a*ieve su* und]/&+4 ,edw>d ,j4 ,brun5kant ,edw>d ,j4 ,brun5kant1 ,director ,division ( ,te*nical ,in=mation ,,unit$ ,,/ates ,,atomic ,,en]gy ,,commission ,dr4 ,gl5n ,t4 ,seaborg1 ,*airman ,james ,t4 ,ramey ,wilfrid ,e4 ,johnson ,dr4 ,cl>5ce ,e4 ,l>son ,illu/ration3 ,,las]s by ,hal ,hellman ,,cont5ts ,,introduction #a ,,! ,,electromagnetic ,,spectrum #e ,,radio ,,waves #i ,,light ,,& ,,! ,,atom #ad ,,:at',s ,,s ,,special ,,ab\t ,,coh]5t ,,light8 #ai ,,controll$ ,,emission #be ,a ,,las] ,,is ,,born #bi ,,las+--,a ,,new ,,^w #cb ,,"s ,,int]e/+ ,,applications #cd ,a ,,multitude ,,( ,,las]s #db ,,communications #dh ,a ,,las] ,,9 ,,y\r ,,future8 #eb ,,sugge/$ ,,ref]5ces #ec ,unit$ ,/ates ,atomic ,en]gy ,commission ,division ( ,te*nical ,in=mation ,libr>y ( ,congress ,catalog ,c>d ,numb]3 #fh-fjgdb #aifh2 #aifi7rev47 ,illu/ration3 ,no?+ ab\t las]s is m a/oni%+ ?an _! ability to produce holograms1 "u arrangem5ts su* z %[n above4 ,two las] beams 7( diff]5t colors7 em]ge f ! curta9 7re>74 ,!y are optically comb9$ 7left c5t]7 & ! comb9$ beam is !n divid$ by prisms1 mirrors & l5ses s t "p ( x %9es on ! figur9es 7=egr\nd7 & "p on ! squ>e holographic plate 7"r c5t]74 ,:5 ! plate is develop$ 7l an ord9>y photographic film71 x w seem to h only a dull gray surface until x is view$ ) spatially coh]5t light 7su* z f a las] or a beam ?r\gh a p9hole7 %9+ ?r\gh x4 ,!n an amaz+1 multi-color$1 ?ree-dim5sional image ( ! figur9es w be visible4 7,see page #ai & ,figure #ac47 ,illu/ration3 ,,las]s ,by ,,hal ,,hellman ,,introduction ,! transi/or bur/ ^u ! electronic sc5e 9 ! #aiejs4 ,almo/ ov]night ! size ( new models ( radios1 television sets1 & a ho/ ( o!r electronic devices %rank l deflat+ balloons4 ,sudd5ly ! h>d-(-he>+ c\ld c>ry _! s\nd amplifi]s 9 _! e>s4 ,te5ag]s c\ld li/5 to favorite music :]ev] !y w5t4 ,ev]y:]e we turn$ ! transi/or 0 mak+ its m>k4 ,!re 0 ev5 a proposal be=e ,congress to require t e home h a transi/or radio 9 case ( em]g5cy4 ,! next developm5t to fire ! imag9ation ( sci5ti/s & eng9e]s 0 ! las]--an in/rum5t t produces an enorm\sly int5se p5cil-?9 beam ( light4 ,mo/ ( u h he>d s mu* ab\t ?is inv5tion x seems h>d to believe t ! fir/ "o 0 built only a few ye>s ago4 ,we 7 told t ! las] 0 go+ to h an ev5 great] effect on our lives ?an ! transi/or4 ,x 0 go+ to replace ev]y?+ f d5ti/s' drills to electric wires4 ,! :ole _w1 x seem$1 ev5tually w\ld be no?+ b a gigantic collection ( las]s t w\ld d ev]y?+ anyone want$4 ,roads w\ld be blaz$ ?r\gh jungles at "o sweep2 our c\ntry w\ld be safe once & = all f int]cont95tal balli/ic missiles2 canc] w\ld be lick$2 comput]s w\ld be small en\gh to c>ry 9 a purse2 & s on & on4 ,yet = ! fir/ c\ple ( ye>s ! las] seem$ able to d no?+ b blaze holes 9 razor blades = ,,tv comm]cials4 ,someh[ ! device nev] seem$ to em]ge f ! laboratory1 prompt+ "o cynic to call x 8an inv5tion 9 se>* ( an application04 ,_m ( ! wild claims came f misund]/&+s on ! "p ( ! press1 o!rs f exagg]ations by a few manufactur]s :o want$ free publicity4 ,b ) ev5 less exotic devices ?an las]s1 ! road f ! laboratory to ! m>ketplace may (t5 be long & h>d4 ,price1 effici5cy1 reliability1 conv5i5ce--^! are all factors t mu/ be consid]$4 ,x soon became cle> t ) some?+ z new z ! las]1 mu* improvem5t 0 necess>y be=e x c\ld be us$ 9 sci5ce & m$ic9e1 & ev5 m be=e x c\ld be us$ 9 indu/ry4 ,x n[ seems1 h[ev]1 t ! turn+ po9t has be5 rea*$4 ,we h se5 las] equipm5t put on ! m>ket = p]=m+ delicate surg]y on ! eye1 spot-weld+ t9y electronic circuits 7,figure #a71 & controll+ ma*9e tools ) amaz+ accuracy 7,figure #b74 ,illu/ration3 ,figure #a ,a comm]cial las] micr[eld]4 ,a microscope is ne$$ = accurate placem5t ( beam en]gy4 ,! pace is quick5+4 ,at lea/ a doz5 manufactur]s h ann\nc$ t !y are design+ las] te*nology into _! products4 ,^! are n laboratory exp]im5ts b practical products = measurem5t & te/+1 & = indu/rial1 milit>y1 m$ical1 & space uses4 ,! ,army1 = example1 has ann\nc$ t x w pur*ase its fir/ equipm5t = use 9 ! field3 a portable1 highly accurate range f9d] = artill]y obs]vation4 ,/ill1 ?is h>dly acc\nts = ! #ajj1jjj1jjj sp5t 9 "o rec5t ye> on las] rese>* & developm5t by "s #ejj laboratories 9 ! ,unit$ ,/ates4 ,! ,u4 ,s4 ,gov]nm5t alone has sp5t ab\t #be1jjj1jjj on las] rese>* 9 a s+le ye>4 ,doz5s1 & p]haps hundr$s1 ( o!r applications are on ! fire--simm]+ or boil+ z ! case may be4 ,"s require p>ticul> te*nical innovations su* z great] p[] or high] effici5cy4 ,o!rs are entirely new applications4 ,"o ( ! mo/ excit+ ( ^! is holography 7pron\nc$ ho ,,log ra phy74 ,holography involves a completely diff]5t approa* to photography4 ,9 addition to m imm$iate applications 9 microscopy1 in=mation /orage & retrieval1 & int]f]ometry1 x promises su* bonuses z #c-;dim5sional color movies & ,,tv som$ay4 ,y h to see ! holographic process 9 op]ation to believe x4 ,"o mom5t y are look+ at :at appe>s to be an und]expos$ or lightly smudg$ photographic plate4 ,!n sudd5ly a true-to-life image ( ! orig9al object spr+s into be+ beh9d ! negative--app>5tly susp5d$ 9 midair6 ,n only is ! full effect ( 8r\ndness0 & dep? !re1 b y c also see any?+ ly+ beh9d ! object's image by mov+ y\r head1 exactly z if ! orig9al sc5e conta9+ ! object 7 really !re4 ,/ill ano!r important field ( application is t ( communications4 ,p]haps because x is less spectacul> ?an burn+ holes 9 razor blades1 we hav5't he>d z mu* ab\t x4 ,yet !re are probably m physici/s & eng9e]s work+ on adapt+ ! las] = use 9 communications ?an on any o!r s+le las] project4 ,! reason = ?is is ! fact t exi/+ communications facilities are becom+ ov]load$4 ,space on transoceanic telephone l9es is already at a premium1 ) wait+ p]iods sometimes runn+ into h\rs4 ,radio 8ham0 op]ators h be5 ?reat5$ ) loss ( "s ( _! be/ op]at+ frequ5cies to meet ! dem& ( em]g+ nations ( ,africa = new *annels4 ,television programs mu/ compete = space on cross-c\ntry networks ) telephone1 telegraph1 & transmission ( data4 ,! increas+ use ( comput]s 9 sci5ce1 bus9ess1 & indu/ry w /ra9 our facilities /ill fur!r4 ,communication satellites w help1 b !y w n give u ! :ole answ]2 & mu* developm5t "w rema9s to be done on satellites4 ,illu/ration3 ,figure #b ,precision control ( a ma*9e tool by las] light4 ,:y ! int]e/ 9 ! las] = communications8 ,9 a rec5t exp]im5t all sev5 ( ! ,new ,york ,,tv *annels 7 transmitt$ ov] a s+le las] beam4 ,9 t]ms ( telephone conv]sations1 "o las] sy/em c\ld !oretically c>ry #hjj1jjj1jjj conv]sations--f\r = ea* p]son 9 ! ,unit$ ,/ates4 ,9 ?is booklet we %all le>n :at !re is ab\t ! las] t gives x s mu* promise4 ,we %all inve/igate :at x is1 h[ x works1 & ! diff]5t k9ds ( las]s !re are4 ,we beg9 by discuss+ "s ( ! m famili> k9ds ( radiation1 su* z radio & micr[aves1 light & ,x rays4 ,,! ,,electromagnetic ,,spectrum ,"s #he ( :at man le>ns comes to him ?r\gh 8 vision 9 response to ! m$ium ( light4 ,yet1 ironically1 x wasn't until ! end ( ! #ag? c5tury t he fir/ began to get an inkl+ ( :at light really is4 ,x took ! great sci5tific g5ius ,isaac ,newton to %[ t s-call$ :ite light is really a comb9ation ( all ! colors ( ! ra9b[4 ,a few ye>s lat] ! ,dut* a/ronom] ,*ri/iaan ,huyg5s introduc$ ! idea t light is a wave motion1 a concept f9ally validat$ 9 #ahjc :5 ! ,briti% physician ,?omas ,"y +5i\sly demon/rat$ int]f]5ce effects 9 waves4 ,?us x 0 f9ally realiz$ t ! only diff]5ce betwe5 ! v>i\s colors ( light 0 "o ( wavel5g?4 ,= light 0 inde$ f\nd to be a wave ph5om5on1 no diff]5t 9 pr9ciple f ! wat] waves y h se5 a ?\s& times4 ,if y /& at ! sea%ore1 y c easily c\nt ! numb] ( waves t approa* ! %ore 9 a m9ute4 ,divide t numb] by #fj & y h ! frequ5cy ( ! wave motion 9 ! famili> unit1 cycles-p]-second 7cps74#a ,y w\ld h to c\nt pretty quickly to d ?is = light1 h[ev]4 ,light waves vibrate or oscillate at ! rate ( "s #djj million million times a second4 ,t's ! vibration rate ( waves ( r$ light2 violet results f vibrations t are j ab\t twice t fa/4 ,) frequ5cies ( ?is magnitude1 discussion & h&l+ ( data & dim5sions are cumb]some & r awkw>d4 ,=tunately !re is ano!r approa*4 ,let's look aga9 at our ocean waves4 ,we see t !re is a regul>ity ab\t !m 7be=e !y beg9 to break on ! %ore74 ,! di/ance f "o cre/ to ! next is significant & is call$ ! wavel5g?4 ,wat] waves are measur$ 9 feet1 & 9 comp>able units light waves are record$ 9 t5-million?s ( an in*--aga9 a v cumb]some numb]4 ,sci5ti/s !re=e use ! metric sy/em#b & h /&>diz$ a unit call$ ! ang/rom#c1 :i* is equal to ! "o-hundr$-million? "p ( a c5timet] 7#aj cm74 ,?us we f9d1 z %[n 9 ,figure #c1 t ! visible light range runs f ! violet at ab\t #djjj ang/roms to r$ at ab\t #gjjj ang/roms4 ,illu/ration3 ,figure #c ,! visible light spectrum ranges betwe5 approximately #djjj & #gjjj ang/roms4 ,wavel5g? 7,ang/roms7 ,violet #djjj-dcjj ,blue #dcjj-ejjj ,gre5 #ejjj-efjj ,yell[ #efjj-ehjj ,orange #ehjj-fajj ,r$ #fajj-gjjj ,at r\ghly ! same "t t ! wavel5g? ( light 0 be+ det]m9$1 ! ,g]man-,briti% a/ronom] ,william ,h]s*el p]=m$ an int]e/+ exp]im5t4 ,he held a !rmomet] 9 turn 9 ! v>i\s colors ( light t _h be5 spread out by an optical prism4 ,z he mov$ ! !rmomet] f ! violet to ! r$1 ! temp]ature read+ rose--& x cont9u$ to rise z he mov$ ! in/rum5t beyond ! r$ area1 :]e no prismatic light c\ld be se54 ,?us ,h]s*el discov]$ infr>$ rays 7! k9d ( heat we get f ! sun7 adjo9+ ! visible r$ light1 & at ! same "t f\nd t !y 7 m]ely a cont9uation ( ! visible spectrum4 ,%ortly !reaft]1 ultraviolet rays 7 f\nd on ! o!r end ( ! visible light b&4 ,"o ( ! mo/ fasc9at+ movem5ts 9 sci5ce has be5 ! con/ant expansion s9ce !n ( bo? ends ( ! radiat+-wave spectrum4 ,! result has come to be call$ ! electromagnetic spectrum1 :i*1 z we see 9 ,figure #d1 encompasses a wide v>iety ( app>5tly diff]5t k9ds ( radiation4 ,above ! visible b& 7! high] frequ5cies71 we f9d ultraviolet light1 ,x rays1 gamma rays1 & "s cosmic rays2 bel[ x are infr>$ radiation1 micr[aves1 & radio waves4 ,only a small proportion ( ! total spectrum is occupi$ by ! visible b&4 ,ano!r po9t ( int]e/ is ! inv]se relation%ip betwe5 wavel5g? & frequ5cy4 ,z "o goes up ! o!r goes d[n4#d ,illu/ration3 ,figure #d ,visible light region spans a t9y portion ( ! total electromagnetic spectrum4 ,frequ5cy 7cps7 ,wavel5g? ,ang/roms ,cosmic rays #aj #j4jjja #j4jja #aj ,gamma rays #j4ja #j4a #aj ,x rays #a #aj #aj ,ultraviolet radiation #ajj #a1jjj ,visible light #aj #aj1jjj ,infr>$ radiation #ajj1jjj ,ang/roms #j4ja #aj ,millimet] waves #j4a #aj ,micr[aves1 rad> #a #aj #aj ,,tv & ,,fm radio #ajj ,%ort wave #a1jjj #aj ,,am radio #aj1jjj ,l[ frequ5cy communications #ajj1jjj #aj1jjj #aj #a1jjj1jjj ,^! _m k9ds ( rays & waves v>y trem5d\sly 9 ! ways !y int]act ) matt]4 ,b !y are all "p ( a s+le family4 ,! only diff]5ce among !m1 z ) ! colors ( ! ra9b[1 lies 9 _! wavel5g?s4 ,9 a few cases1 z we %all see lat]1 ! mode ( g5]ation is also diff]5t4 ,! b& ( radiation /ret*+ f ! infr>$ to cosmic rays has be51 up to n[1 l>gely ! conc]n ( physical sci5ti/s4 ,because ( _! high frequ5cies1 ^! radiations are g5]ally h&l$1 :5 calculations or measurem5ts mu/ be made1 9 t]ms ( wavel5g?4 ,radio & micr[aves#e1 on ! o!r h&1 h be5 m 9 ! doma9 ( communications eng9e]s & are m likely to be discuss$ 9 t]ms ( frequ5cy4 ,?us x is t y\r radio is m>k$ (f 9 kilocycles1 or ?\s&s ( cycles p] second1 :ile light is describ$ z radiation 9 ! #djjj to #gjjj ang/rom b&4 ,! relative newness ( ! v>i\s radiations has kept sci5ti/s busy le>n+ ab\t !m &1 z in=mation & exp]i5ce h accumulat$1 putt+ !m to "w4 ,,radio ,,waves ,"o ( ! fir/ ( ! newly discov]$ electromagnetic radiations to be put to "w 0 ! radio wave1 :i* is *>act]iz$ by long wavel5g? & l[ frequ5cy4#f ,! l[ frequ5cy makes x relatively easy to produce a wave hav+ virtually all its p[] conc5trat$ at "o frequ5cy4 ,! advantage ( ?is capability becomes obvi\s aft] a mom5t's ?\ght4 ,?9k = example ( a gr\p ( p lo/ 9 a =e/4 ,if !y he> s\nds ( a se>* p>ty (f 9 ! di/ance1 all likely w beg9 to %\t 9 v>i\s ways = help4 ,n a v effici5t process1 is x8 ,b suppose all ! en]gy go+ into ! production ( ?is noise c\ld be conc5trat$ 9 a s+le %\t or :i/le4 ,cle>ly1 _! *ances ( be+ f\nd w\ld be mu* improv$4 ,illu/ration3 ,figure #e 7a7 ,temporally coh]5t radiation4 7b7 ,temporally incoh]5t radiation4 ,! s+le frequ5cy capability ( radio waves has be5 giv5 ! "n temporal coh]5ce 7or coh]5ce 9 "t7 & is illu/rat$ 9 ,figure #e4 ,"p a %[s a s+le s9e wave1 ! common way ( repres5t+ electromagnetic radiation1 & p>ticul>ly temporally coh]5t radiation4 ,9 b we see :at temporally incoh]5t radiation 7su* z ! mix$ s\nds ( ! /r&$ p>ty7 w\ld look l4 ,x 0 on ,*ri/mas ,eve #aijf t music & spee* came out ( a radio receiv] = ! fir/ "t4 ,today ! sight ( someone walk+1 rid+1 or /udy+ ) an e>piece plugg$ into a transi/or radio is common4 ,b ! e>ly radio en?usia/s _h to we> e>phones because x takes consid]able p[] to activate a l\dspeak] & ! receiv$ signal 0 q weak4 ,"s means ( increas+1 or amplify+1 ! signal 0 ne$$ if ! process 0 to advance beyond ?is primitive /age4#g ,! use ( vacuum tube or electron tube amplifi]s is s widespread t x is unnecess>y to expla9 _! op]ations "h 9 any detail4 ,x is important t ! pr9ciple ( amplification be und]/ood1 h[ev]4 ,! input or in=mation wave causes ! grid to act z a sort ( faucet z %[n 9 ,figure #f4 ,t is1 x controls ! fl[ ( electrons 7! curr5t 9 ! circuit7 f ca?ode to anode4 ,a weak signal c !re=e cause a simil>1 b mu* /rong]1 signal to appe> 9 ! circuit4 ,! l>g] signal is subsequ5tly us$ to p[] a l\dspeak] 9 ! radio set4 ,illu/ration3 ,figure #f ,amplification by a ?ree-elem5t vacuum tube4 ,p[] s\rce ,ca?ode ,grid ,input wave ,anode ,output wave ,! amplification pr9ciple c be appli$ 9 ano!r equally important way4 ,once a signal gets />t$ 9 ! circuit1 "p ( x c be f$ back into ! input ( ! circuit4 ,?us ! signal is made to g 8r\nd & r\nd01 cont9u\sly reg5]at+ itself4 ,! device has become an oscillator1 t is1 a frequ5cy g5]ator t produces a /eady & temporally coh]5t wave4 ,! frequ5cy ( ! wave c be rigidly controll$ by suitable circuitry4 ,! oscillator plays a vital "p 9 radio transmission1 = a transmitt] beams en]gy cont9u\sly1 n j :5 s\nd is be+ c>ri$4 ,! oscillator g5]ates :at is call$ a 8c>ri] wave04 ,in=mation1 su* z spee* or music1 is c>ri$ 9 ! =m ( audio 7detectable-by-e>7 frequ5cies1 :i* ride 8piggyback0 on ! c>ri] wave4 ,9 o!r words1 ! c>ri] wave is modulat$1 or v>i$1 9 su* a way t x c c>ry mean+ful in=mation4 ,! famili> expressions ,,am & ,,fm1 = example1 /& = ,amplitude ,modulation & ,frequ5cy ,modulation--two diff]5t ways ( impress+ in=mation on ! c>ri] wave4 ,figure #g %[s a basic & an amplitude- 7or height-7 modulat$ wave4 ,illu/ration3 ,figure #g 7a7 ,unmodulat$ radio wave4 7b7 ,amplitude-modulat$ wave c>ries in=mation4 ,! electron tube made its giant contribution to radio1 television1 & o!r electronic devices by mak+ x possible to g5]ate1 detect1 & amplify radio waves4 ,because radio waves are easily controll$1 some?+ useful c be done ) !m4 ,suppose we set up five radio transmitt]s1 all beam+ at ! same frequ5cy4 ,! waves might look l ^? %[n 9 ,figure #h4 ,al?\gh ! waves are temporally 7or "t7 coh]5t1 !y are out ( /ep1 & n spatially coh]5t4 ,b s9ce good control is possible 9 radio circuits1 we c =ce ea* ant5na to radiate 9 phase 7t is1 9 /ep7 ) ! o!rs1 ?us produc+ fully coh]5t radiation 7,figure #h74 ,illu/ration3 ,figure #h 7a7 ,spatially incoh]5t radiation4 7b7 ,spatially coh]5t radiation4 ,su* a process c increase ! radiation p[] to an almo/ unlimit$ degree4 ,b x does no?+ to solve ! problem ( ! limit$ total c>ry+ capacity ( ! radio spectrum4 ,! mo/ obvi\s & be/ way out ( ?is difficulty is to raise ! op]at+ frequ5cies into ! high] frequ5cy b&s4 ,!re are two reasons = ?is4 ,fir/1 x is cle> t ! wid] ! frequ5cy b& 7! numb] ( frequ5cies available7 ) :i* we "w1 ! great] ! numb] ( communication *annels t c be creat$4 ,b second1 & m important1 ! high] ! frequ5cy ( ! wave1 ! great] is its in=mation-c>ry+ capacity4 ,9 almo/ ! same way t a l>ge truck c c>ry a bigg] load ?an a small "o1 ! great] numb] ( cycles p] second 9 a high frequ5cy wave p]mits x to c>ry m in=mation ?an a l[ frequ5cy wave4 ,h[ev]1 high frequ5cies mu/ be g5]at$ 9 diff]5t ways ?an l[ frequ5cy waves are2 !y require special equipm5t to h&le !m4 ,radio waves are transmitt$ by caus+ masses ( free electrons to oscillate or sw+ back & =? 9 ! transmitt+ ant5na4 7,any "t electrons are made to *ange _! spe$ or direction !y radiate electromagnetic en]gy47 ,ea* k9d ( oscillator has "s limit to ! frequ5cies at :i* x c op]ate4 ,! ?ree-elem5t electron tube has be5 successfully develop$ to oscillate at frequ5cies up to1 b n includ+1 ! vibration rate ( ! micr[ave region4 ,"h ord9>y tubes h tr\ble = ! unexpect$ reason t free electrons are j too sl[ 9 _! reactions to oscillate z rapidly z requir$ 9 micr[ave transmission4 ,to ov]come ?is ob/acle1 two new types ( electron tubes 7 develop$3 ! kly/ron 9 #aich & ! travel+-wave tube "s #aj ye>s lat]4 ,^! lift$ op]ation well up into ! micr[ave region2 x 0 ! kly/ron t made w>time rad> possible4 ,today _m communication l9ks dep5d heavily ^u micr[ave frequ5cies4 ,at ?is po9t 9 our /ory we h a situation :]e l[ temporally coh]5t radio waves & micr[aves c be g5]at$1 b no?+ ( high] frequ5cy4 ,communications eng9e]s h gaz$ wi/fully1 b almo/ hopelessly1 at light waves1 ^: frequ5cies are millions ( times high] ?an radio waves4 ,?us1 j by way ( example1 "s #ae million sep>ate ,,tv *annels c\ld op]ate 9 ! frequ5cy range betwe5 r$ & orange 9 ! visible b&4 ,:at1 !n1 is ! problem8 ,:y is light s mu* m difficult to h&le8 ,,light ,,& ,,! ,,atom ,s9ce light waves h su* high frequ5cies1 a diff]5t mode ( g5]ation comes into play4 ,we c no long] c\nt on ! controll$ movem5t ( free electrons outside atoms & molecules4 ,r1 light & all ! radiations 9 ! high] frequ5cies are g5]at$ by ! movem5t ( electrons inside atoms & molecules4 ,let u review mom5t>ily ! mod]n1 albeit highly simplifi$1 conception ( an atom4 ,rememb] t no "o has yet se5 "o4 ,we describe ! atom on ! basis ( h[ x acts1 z well z h[ x reacts to ?+s sci5ti/s d to x4 ,= ! pres5t purpose1 ! be/ model we h ( ! atom is t ( a m9iature sol> sy/em1 ) a nucleus or heavy "p at ! c5t] & a cl\d ( electrons da%+ ar\nd ! nucleus 9 fix$ orbits4 ,! t]m 8fix$ orbits0 is us$ advis$ly4 ,our planet moves 9 a c]ta9 orbit ar\nd ! sun4 ,if we atta*$ a l>ge en\gh rocket to ! e>? we !oretically c\ld move x clos] to or f>!r away f ! sun4 ,9 ! atom1 we h le>n$1 ?is _c be done4 ,an electron c only exi/ 9 "o ( a c]ta9 numb] ( fix$ orbits2 diff]5t k9ds ( atoms h diff]5t numb]s ( orbits4 ,we might ?9k 9 t]ms ( an elevator t c only /op at ! v>i\s floors ( an ap>tm5t build+4 ,ea* upp] floor is l an orbit ( ! electron4 ,b y get no?+ = no?+ 9 ! _w ( physics1 & j z x takes en]gy to raise an elevator to a high] floor1 x takes en]gy to move an electron to an out] orbit4 ,h5ce ! atom is said to be rais$ to high] en]gy levels :5 an electron is nudg$ to an out] orbit4 ,! en]gy input c be ( _m diff]5t k9ds4 ,examples are heat1 pressure1 electrical curr5t1 *emical en]gy1 & v>i\s =ms ( electromagnetic radiation4 ,if too mu* en]gy is put into ! elevator x goes fly+ out ! ro(4 ,if too mu* en]gy is put into ! atom1 "o or m ( its electrons w g fly+ out ( ! atom4 ,?is is call$ ionization1 & ! atom1 n[ m9us "o ( its negative electrons & !re=e positively *>g$1 is call$ a positive ion4 ,b if ! "r am\nt ( en]gy is put into ! atom1 "o ( its electrons w m]ely be rais$ to a high] en]gy level4 ,%[n 9 ,figure #i1 = in/ance1 are ! gr\nd /ate 7,circle ,no4 #a7 & two possible high] en]gy levels4 ,z y c see !re are ?ree possible transitions4 ,illu/ration3 ,figure #i ,s*ematic repres5tation ( ! electron orbits & en]gy levels ( an atom4 ,ea* circle repres5ts a sep>ate possible orbit & ea* arr[ a possible en]gy level diff]5ce4 ,! high] en]gy levels are abnormal1 or excit$1 /ates1 h[ev]1 & ! electron w %ortly fall back to its normal 7gr\nd /ate7 orbit 7assum+ "s o!r electron has n fall5 into x fir/74 ,9 ord] = ! electron to d ?is 7g back to its normal orbit71 x mu/ give (f ! en]gy x has acquir$4 ,?is x does 9 ! =m ( electromagnetic radiation4 ,! en]gy diff]5ce betwe5 ! two levels w det]m9e :at k9d ( radiation is emitt$1 = !re is a direct correlation betwe5 en]gy & frequ5cy4#h ,if ! en]gy diff]5ce betwe5 ! two levels is su* t ! frequ5cy ( emitt$ radiation is r\ghly betwe5 #aj & #aj cycles p] second1 we see ! radiation z light4 ,:5 m en]gy is add$1 ! radiation em]ges z ultraviolet or ,x rays4 ,9 o!r words ! high] ! en]gy diff]5ce1 ! high] ! frequ5cy1 & vice v]sa4 ,?us x is t cosmic rays1 ) ! highe/ frequ5cies kn[n to man1 c pass "r ?r\gh u z if we w]5't !re4 ,?is simple picture ( en]gy levels & associat$ frequ5cies doesn't q hold = ord9>y :ite light1 h[ev]4 ,su* light is g5]ally produc$ by a process call$ inc&esc5ce1 :i* results f ! heat+ ( a mat]ial until x gl[s4 ,true1 ! atoms ( ! inc&esc5t mat]ial are be+ rais$ to high] en]gy levels by *emical en]gy 7z 9 fire71 electricity 7light bulb71 or nucle> en]gy 7! sun74 ,9 a hot solid1 h[ev]1 ! explanation becomes m complicat$4 ,_m diff]5t electronic configurations are possible & ! diff]5ces 9 en]gy among ! v>i\s levels 7:i* c be _m m ?an ! ?ree %[n 9 ,figure #i7 v>y only slightly f "o ano!r4 ,! result is a wide b& ( radiation4 ,?us1 :ile ! inc&esc5t electric bulb is a great advance ov] fire1 x is /ill a v ineffici5t s\rce ( light4 ,because x dep5ds ^u inc&esc5ce1 a consid]able portion ( ! electrical input goes into ! production ( unwant$ heat1 = ! bulb's filam5t radiates 9 ! infr>$ z well z ! visible region4 ,= provid+ illum9ation1 ! fluoresc5t tube is f> m effici5t ?an ! inc&esc5t lamp3 a #dj-watt fluoresc5t tube gives z mu* light z a #aej-watt inc&esc5t light4 ,?is is because its radiation is m controll$1 op]at+ m 9 accord ) our description ( electronic en]gy levels4 ,h5ce m ( its output is 9 ! desir$ visual region ( ! spectrum4 ,9 c]ta9 types ( light+1 p>ticul> en]gy level *anges may pr$om9ate1 lead+ to ! *>act]i/ic colors ( neon tubes & vapor lamps4 ,al?\gh ! result+ radiation b&wid? is n>r[ en\gh 9 ^! devices to appe> z a def9ite color in/ead ( ! broad spectrum we "k z :ite1 x is /ill q broad4 ,9 o!r words1 ! radiation is /ill frequ5cy incoh]5t--& x is /ill spatially incoh]5t4 ,to und]/& ?is1 let u return = a mom5t to ! gr\p ( radio ant5nas we %[$ 9 ,figure #h4 ,all ( !m1 y w recall1 c\ld be made to radiate 9 phase4 ,9 ! production ( light1 h[ev]1 ea* ant5na is replac$ by a s+le atom6 ,?is creates two problems4 ,fir/1 because ! en]gy /or$ 9 ! atom is q small1 x comes out n z a cont9u\s wave b z a t9y packet ( radiation--a photon4#i ,x has an effect m l ! hack ( an ax ?an ! buzz ( a p[] saw4 ,second1 atoms are notori\sly 8individuali/ic04 ,:5 a bat* ( atoms 9 a mat]ial has be5 rais$ to high] en]gy levels !re is no way to "k 9 :at ord]1 or 9 :at direction1 !y w release _! en]gy4 ,?is k9d ( process is call$ spontane\s emission1 s9ce ea* atom 8makes up its own m9d04 ,all we "k is t )9 a c]ta9 p]iod ( "t--a %ort p]iod1 to be sure--a c]ta9 p]c5tage ( ^! high] en]gy atoms w release _! photons4 ,illu/ration3 ,figure #aj ,ord9>y light is a jumble ( frequ5cies1 directions1 & phases4 ,:at we h1 !n1 is incoh]5t radiation--a jumble ( frequ5cies 7or colors71 directions1 & phases4 ,su* light1 symboliz$ 9 ,figure #aj1 works well en\gh 9 light+ up ?is page1 b is almo/ wor?less z a c>ri] ( in=mation 7& 9 o!r ways1 z we %all see %ortly74 ,ab\t ! be/ t c be done ) x is to turn x on & (f 9 a sort ( visual ,morse code1 :i* is exactly :at is done on ! bl9k] communication sy/ems sometimes us$ = %ip-to-%ip communication4 ,9 o!r words1 ord9>y light _c be modulat$ z radio waves c4 ,x is ( int]e/ to note1 h[ev]1 t ord9>y :ite light c be made coh]5t1 to "s ext5t1 b at a v high co/ 9 ! int5sity ( ! light4 ,= example1 we might fir/ pass ! light ?r\gh a s]ies ( filt]s1 ea* ( :i* w\ld subtract "s portion ( ! spectrum1 until only ! desir$ wavel5g? came ?r\gh4 ,z c be se5 9 ,figure #aa1 only a small fraction ( ! orig9al light w\ld be left4 ,illu/ration3 ,figure #aa ,obta9+ coh]5t radiation ! h>d way4 ,filt]s & p9hole block all b a small am\nt ( ! orig9al radiation4 ,incoh]5t ,filt]s ,coh]5t 9 "t ,p9hole ,coh]5t 9 "t & space ,we w\ld !n h mono*romatic 7"o color7 light1 :i* is temporally coh]5t radiation1 b x w\ld /ill be spatially incoh]5t4 ,9 our diagram1 we %[ ?ree mono*romatic waves4 ,if we !n pass$ ?is light ?r\gh a t9y p9hole z %[n1 mo/ ( ^! few rema9+ waves w\ld be block$2 ! ones t got ?r\gh w\ld be pretty mu* 9 /ep4 7,9 a simil> mann]1 a true po9t s\rce ( light w\ld produce spatially coh]5t radiation2 b1 z 9 ! process describ$ "h1 !re w\ldn't be v mu* ( x47 ,we h1 f9ally1 obta9$ coh]5t light4 ,! important ?+ ab\t ! las] is t1 by its v nature1 x produces coh]5t light automatically4 ,n[4444 ,,:at',s ,,s ,,special ,,ab\t ,,coh]5t ,,light8 ,s desirable are ! qualities ( coh]5t light t ! complicat$ filt]+ process describ$ above has actually be5 us$4 ,= example1 "o ,briti% exp]im5t]1 ,d5nis ,gabor1 us$ x 9 ! #aidjs 9 an attempt to make a bett] microscope4 ,b s great 0 ! ef=t1 & s meag] ! result+ light1 t ?is project 0 ab&on$4 ,9 ! c\rse ( ,dr4 ,gabor's exp]im5ts1 h[ev]1 he did manage to make a special k9d ( picture1 us+ coh]5t light1 :i* he call$ a hologram4 ,he d]iv$ ! "n f two ,greek words mean+ a :ole picture4 ,we %all see :y 9 a mom5t4 ,ord9>y black & :ite photographs m]ely record d>ks & lights1 or ! int5sity ( ! illum9ation1 !reby provid+ a scale ( grays1 no?+ m4 ,b because waves ( coh]5t light consi/5tly ma9ta9 _! relative spac+1 !y c be us$ to record additional in=mation1 namely ! di/ance f objects4 ,= example1 if we %9e a beam ( coh]5t 7las]7 light betwe5 two objects we c1 kn[+ ! light wavel5g?1 det]m9e ! di/ance betwe5 !m to a high degree ( accuracy4 ,! basic idea is diagram$ 9 ,figure #ab4 ,x c be se5 t ! numb] ( waves times ! wavel5g? gives ! precise di/ance 7to )9 #a wavel5g? ( light7 f ! las] s\rce to ea* object4 ,b ?is w\ld be a difficult process to implem5t4 ,a bett] way1 & "o t is already 9 op]ation1 is to use conv5tional me?ods to measure ! approximate di/ance & use ! las] beam = precise or f9e measurem5t4 ,9 ! device %[n 9 ,figure #b1 ! beam is split into two p>ts4 ,"o "p is kept 9 ! in/rum5t itself to act z a ref]5ce4 ,! o!r is aim$ at a reflector1 :i* s5ds x back to a detector 9 ! ma9 device1 :]e x is automatically comp>$ ) ! ref]5ce beam4 ,if ! two beams are 9 phase 7t is1 if _! cre/s are sup]impos$71 ! waves comb9e & produce a high int5sity beam at ! detector4 ,z ! reflector moves clos] to or f>!r away f ! las] s\rce ! beam int5sity decreases & !n increases aga9 z ! wave cre/s move 9 & out ( phase4 ,! in/rum5t c\nts ! *anges & displays ! di/ance ! reflector moves1 z a function ( ! wavel5g?s1 on ! control cab9et met]s4 ,illu/ration3 ,figure #ab ,pr9ciple ( di/ance measurem5t us+ coh]5t light4 ,wavel5g? times numb] ( waves gives precise di/ance betwe5 las] & object4 ,di/ance to be measur$ ,las] ,object ,no4 #b #a ,wavel5g? ,object ,no4 #a ,s9ce ! ,^w ,= ! ,int]action ( ! ,waves 9 a ,sy/em ,l ,?is ,is 8,int]f]5ce01 ! ,measurem5t ,process ,is ,call$ int]f]ometry 7,pron\nc$ 9 ,t] ,f] ,om ,e ,try74 ,al?\gh ,n ,new1 ,x ,c ,n[ ,be ,appli$ ,= ! ,fir/ ,"t 9 ,ma*9e ,tool ,applications1 ,provid+ ! ,accuracy ,ne$$ 9 ,?is ,age ( ,space ,te*nology & ,microm9iaturization4 ,measurem5ts ,) a ,las] ,int]f]omet] ,c ,be ,made ,) an ,accuracy ( #j4e ,"p ,p] ,million at ,di/ances ,up to #bjj ,in*es4 ,su* ,precision ,0 ,previ\sly ,unhe>d ( 9 a ,ma*9e ,%op ,environm5t1 ,hav+ ,be5 ,limit$ to ,laboratory ,measurem5ts1 & ,only at ,a ,range ( a ,few ,in*es4 ,"u ,simil> ,laboratory ,conditions1 ,measurem5ts by ,las] ,int]f]ometry ,n[ ,detect ,movem5ts ( #aj ,c5timet]1 a ,di/ance ,approa*+ ! ,dim5sions ( an ,atomic ,nucleus4 ,n[ let u suppose we exp& ! las] beam z %[n on page #bb1 &1 ) ! aid ( a mirror1 direct "p ( x 7! ref]5ce beam7 at a photographic plate4 ,! rema9+ portion ( ! div]g+ beam is us$ to illum9ate ! object to be photograph$4 ,"s ( ?is light 7! object beam7 is reflect$ t[>d ! plate & c>ries ) x in=mation ab\t ! object1 z indicat$ by ! wavy l9e4 ,9 ! region :]e ^! two beams int]sect1 int]f]5ce occurs1 & a sample ( ?is int]f]5ce is record$ )9 ! photographic emulsion4 ,:]e two cre/s meet a d>k spot is record$2 :]e ! waves are out ( phase ! process$ plate is cle>4 ,! result is a hologram1 a complex patt]n ( 8fr+es01 *>act]i/ic ( ! cont\r & light & d>k areas ( ! object1 z well z its di/ance f ! plate4 ,^! fr+es h ! ability to diffract light rays4 ,:5 light f a las]1 or a po9t s\rce ( :ite light1 is direct$ at ! hologram f ! same direction z ! ref]5ce beam1 "p ( ! light is 8b5t0 s t x appe>s to come f ! place once occupi$ by ! object4 ,! result is a rem>kably reali/ic #c-;dim5sional image4 ,!re1 9 a nut%ell1 is ! incr$ible new te*nique ( holography4 ,! extreme ord] ( las] light is illu/rat$ by ! regul>ity ( ! dots on ! cov] ( ?is booklet4 ,?is /range k9d ( light provides u ) yet o!r advantages4 ,inde$1 "o ( ! mo/ important is ! fact t ! en]gy ( ! las] is n be+ spray$ out 9 all directions4 ,all ( x is conc5trat$ 9 ! n>r[ beam t em]ges f ! device4 ,& x /ays n>r[4 ,las] light has already be5 %one on ! moon1 ! beam spread+ out to only a few miles 9 travel+ !re f e>?4 ,! be/ optical se>*light beam w\ld spread wid] ?an ! moon itself1 ?us dissipat+ its en]gy4 ,x is = ?is reason1 z well z its temporal coh]5ce1 t las] light is be+ consid]$ = communications4 ,a n>r[ beam is p>ticul>ly important = space communications because ( ! long di/ances involv$4 ,b x is also possible to focus las] light z no light has ev] be5 focus$ be=e4 ,at close range a las] beam c be focus$ d[n to a circle j a few wavel5g?s across1 conc5trat+ its en]gy & mak+ x possible to drill holes only #j4jjjb in* 9 diamet]4 ,! photo on page #eb %[s ! exquisite control t c be ex]cis$4 ,let u see :at ?is focusability means 9 t]ms ( p[]4 ,consid]1 by way ( analogy1 a da9ty #ajj-p\nd lady 9 a pair ( spike-heel$ %oes4 ,z %e takes a /ep1 h] weight w be conc5trat$ on "o ( ^? heels4 ,if ! area ( ! heel is1 say1 "o qu>t] ( a squ>e in* 7 in*71 ! pressure ex]t$ on ! poor tile or c>pet rises to #djj p\nds p] squ>e in* 7#d #ajj7 & if ! heel is only in* on a side1 ! pressure w be #afjj p\nds p] squ>e in*6 ,illu/ration3 ,mak+ & ,view+ a ,hologram ,,mak+ ,a ,,hologram ,object ,object beam ,holographic plate ,mirror ,ref]5ce beam ,las] ,,view+ ,a ,,hologram ,hologram ,image ,eye ,coh]5t light s\rce ,:at we are gett+ at1 ( c\rse1 is ! fact t ! coh]5ce ( ! las] beam p]mits x to be conc5trat$ into a t9y area4 ,?us :atev] total en]gy is be+ s5t out by ! las] c be conc5trat$ to ! po9t :]e its effective en]gy is trem5d\s4 ,! sun emits "s #fejj watts p] squ>e c5timet]4 ,las] beams h already rea*$ #ejj million watts p] squ>e c5timet]4 ,b ! p[] ( ! las] does n d]ive solely f its ability to be focus$4 ,ev5 an unfocus$ beam is sev]al times m p[]ful ?an ! sun's output 7p] squ>e c5timet]74 ,illu/ration3 ,figure #ac ,! typical hologram1 looks l a geometric design1 b x conta9s m in=mation ?an w\ld an ord9>y photograph4 ,! images bel[1 made f a hologram1 %[ ! detail1 app>5t solidity1 & p>allax effect ( ! recon/ruct$ light waves4 ,! p>allax effect is ! ability to see ar\nd ! objects j z "o c\ld if !y 7 really !re4 7,see frontispiece47 ,illu/ration3 ,model tank ,illu/ration3 ,tank1 f ano!r angle ,! crucial diff]5ce betwe5 ! sun's light or any ord9>y k9d ( light & las] light lies 9 ! ext5t to :i* ! emission ( en]gy c be controll$4 ,9 ! production ( ord9>y light ! atoms1 z we "k1 emit spontane\sly1 or 9 an uncontroll$ fa%ion4 ,b if ! atoms c\ld be =c$ to take 9 ! prop] am\nt ( en]gy1 /ore x1 & release x :5 we want$ !m to1 we w\ld h /imulat$1 r ?an spontane\s1 emission4 ,?is1 h[ev]1 is practically ! same z ! amplification pr9ciple we discuss$ e>li]4 ,9 t case1 a small radio signal is jack$ up into a l>ge "o by /imulat+ an available p[] s\rce to release its en]gy at ! same wavel5g? & 9 /ep ) ! small] signal4 ,! "q is1 h[ c we d ?is ) light8 ,,controll$ ,,emission ,! las] & its p>5t1 ! mas]1 c be trac$ back half a c5tury to its !oretical beg9n+s4 ,! great physici/ ,alb]t ,e9/e9 is mo/ widely kn[n = 8 "w 9 relativity4 ,b he did e>ly & important "w on t o!r gigantic #bj? c5tury sci5tific a*ievem5t1 ! quantum !ory4#aj ,9 "o ( 8 pap]s1 publi%$ fir/ 9 ,zuri*1 ,switz]l&1 9 #aiaf1 ,e9/e9 %[$ t controll$ emission ( light en]gy c\ld be obta9$ f an atom "u c]ta9 conditions4 ,:5 an atom or molecule has someh[ _h its en]gy level rais$1 ! release ( ?is /or$ en]gy c\ld be /imulat$ by subject+ ! atom or molecule to a small 8%ot0 ( electromagnetic radiation ( ! prop] frequ5cy4 ,e9/e9 wrote t :5 su* a photon ( en]gy caus$ an electron to drop f a high] to a l[] orbit1 ! electron w\ld emit ano!r photon ( ! same frequ5cy & 9 ! same direction z ! "o t hit x4#aa ,9 o!r words1 ! en]gy ( ! emitt$ photon w\ld be add$ to t ( ! photon t /imulat$ ! emission 9 ! fir/ place4 ,"h1 pot5tially1 0 light amplification4 ,! ?ree major factors1 absorption ( en]gy1 spontane\s emission1 & /imulat$ emission are diagramm$ 9 ,figure #ad4 ,!re ! matt] lay = m ?an #cj ye>s4 ,9 #aiea ,*>les ,h4 ,t[nes1 !n on ! ,columbia ,univ]sity faculty1 0 int]e/$ 9 ways ( ext5d+ to /ill high] frequ5cies ! range ( micr[aves available = use 9 communications & 9 o!r sci5tific applications4 ,t[nes & o!r sci5ti/s :o 7 int]e/$ 9 ! problem 7 to meet 9 ,wa%+ton1 ,d4 ,c41 on ! #bf? ( ,april4 ,! night be=e ! meet+ he slept 9 a small ,wa%+ton hotel2 b he awoke at #e3cj--pond]+1 pond]+ ! high frequ5cy problem4 ,he dress$ & took a walk1 !n sat on a p>k b5* & savor$ ! beauty ( azaleas 9 bloom4 ,b all ! :ile 8 m9d 0 runn+ ov] ! v>i\s aspects ( ! problem4 ,illu/ration3 ,figure #ad ,an atom c release absorb$ en]gy spontane\sly or x c be /imulat$ to d s4 ,be=e ,aft] ,excit$ /ate ----- ---- ,absorption ,relax$ /ate ---- ----- ,excit$ /ate ---- ----- ,spontane\s emission ,relax$ /ate ----- ---- ,excit$ /ate ---- ----- ,/imulat$ emission ,relax$ /ate ----- ---- ,sudd5ly ! answ] came to him4 ,normally m ( ! molecules 9 any sub/ance are 9 l[-en]gy /ates ?an 9 high ones4 ,he w\ld *ange ! natural balance & create a situation ) an abnormally l>ge numb] ( high-en]gy molecules4 ,!n he w\ld /imulate !m to emit _! en]gy by nudg+ !m ) micr[aves4 ,"h 0 amplification4 ,he c\ld ev5 take "s ( ! emitt$ radiation & fe$ x back into ! device to /imulate additional molecules1 !reby creat+ an oscillator4 ,?is fe$back arrangem5t1 he knew1 c\ld be c>ri$ out 9 a cavity1 :i* w\ld resonate 7j l an organ pipe7 at ! prop] frequ5cy4 ,! resonator w\ld be a box ^: dim5sions 7 comp>able ) ! wavel5g? ( ! radiation1 t is1 a few c5timet]s on a side4 ,on ! back ( an envelope he figur$ out "s ( ! basic requirem5ts4 ,?ree ye>s1 & _m exp]im5ts1 lat] ! mas] 7micr[ave amplification by stimulat$ emission ( radiation7 0 a reality4 ,! orig9al mas] 0 a small metal box into :i* excit$ ammonia molecules 7 add$4 ,:5 micr[aves 7 beam$ into ! excit$ ammonia ! box emitt$ a pure1 /rong beam ( high frequ5cy micr[aves1 f> m temporally coh]5t ?an any t _h ev] be5 a*iev$ be=e4 ,! output ( an ammonia mas] is /able to "o "p 9 #ajj billion1 mak+ x an extremely accurate atomic 8clock04#ab ,moreov]1 ! amplify+ prop]ties ( mas]s h be5 f\nd to be v useful = magnify+ fa9t radio signals f space1 & = satellite communications4 ,ammonia gas 0 *os5 = ! fir/ mas] because molecules ( ammonia h two individual en]gy /ates t are sep>at$ by a gap correspond+ 9 frequ5cy to #bc1hgj megacycles 7#bc1hgj million cycles7 p] second4 ,ammonia molecules also react to a nonuni=m electric field 9 ways t dep5d on _! en]gy level3 l[-level molecules c be attract$ & high-level ones repell$ by ! same field4 ,?us x is possible to sep>ate ! l[-en]gy molecules f ! high1 & to get ! excit$ molecules into ! cavity )\t too mu* tr\ble4 ,?is proc$ure = gett+ ! majority ( atoms or molecules 9 a conta9] into a high] en]gy /ate1 is call$ population inv]sion & is basic to ! op]ation ( bo? mas]s & las]s4 ,x %\ld be not$ t two ,russians1 ,n4 ,g4 ,basov & ,a4 ,m4 ,prokhorov1 7 work+ along simil> l9es indep5d5tly ( ,t[nes4 ,9 #aieb !y pres5t$ a pap] at an ,all-,union 7,u4,s4,s4,r47 ,conf]5ce1 9 :i* !y discuss$ ! possibility ( con/ruct+ a 8molecul> g5]ator01 t is1 a mas]4 ,_! proposal1 fir/ publi%$ 9 #aied1 0 9 _m respects simil> to ,t[nes's4 ,9 #aiee1 ,basov & ,prokhorov discuss$1 9 a %ort note1 a new way to obta9 ! active atomic sy/ems = a mas]1 a me?od t turn$ out to be ( great importance4 ,?us on ,octob] #bi1 #aifd1 ! ,nobel ,prize 9 ,physics 0 aw>d$1 n only to ,t[nes1 b to ,basov & ,prokhorov z well4 ,! aw>d 0 = fundam5tal "w 9 ! field ( quantum electronics1 :i* has l$ to ! con/ruction ( oscillators & amplifi]s bas$ on ! 8as]0 pr9ciple4 ,a ,,las] ,,is ,,born ,foll[+ ! mas] developm5t1 !re 0 mu* speculation ab\t ! possibility ( ext5d+ ! pr9ciple to ! optical region4 ,inde$ ! fir/ las]s--light amplification by stimulat$ emission ( radiation--7 call$ 8optical mas]s04 ,! difficulty1 ( c\rse1 0 t optical wavel5g?s are s t9y--ab\t _/1 t ( micr[aves4 ,! mas] pr9ciple dep5d$ ^u a physical resonator1 a box a few c5timet]s 7or ev5 millimet]s7 9 l5g?4 ,b at millimet] wavel5g?s1 su* resonators are already s small t !y are h>d to make accurately4 ,mak+ a box _/1 t size 0 out ( ! "q4 ,ano!r approa* 0 necess>y4 ,9 #aieh ,a4 ,l4 ,s*awl[ ( ,bell ,telephone ,laboratories & ,dr4 ,t[nes outl9$ ! !ory & propos$ a /ructure = an optical mas]4 ,!y sugge/$ t resonance c\ld be obta9$ by mak+ ! waves travel back & =? along a relatively long1 ?9 column ( amplify+ sub/ance t _h p>allel reflectors at ! ends4 ,aft] _! !ory ( ! optical mas] _h be5 publi%$1 ! race to build ! fir/ actual device began 9 e>ne/4 ,! w9n]1 9 #aifj1 0 ,dr4 ,t4 ,h4 ,maiman1 !n ) ,hughes ,aircraft ,company4 7,he is n[ presid5t ( ,maiman ,associates47 ,! active sub/ance he us$ 0 a s+le cry/al ( ruby1 ) ! ends gr\nd flat & silv]$4 ,ruby is an alum9um oxide 9 :i* a small fraction ( ! alum9um atoms 9 ! molecul> /ructure1 or lattice1 h be5 replac$ ) *romium atoms4 ,^! atoms absorb gre5 & blue light & h5ce imp>t a r$ color to ! ruby4 ,! *romium atoms c be boo/$ f _! gr\nd /ate into excit$ /ates :5 !y absorb ! gre5 or blue light4 ,?is process1 by :i* population inv]sion is a*iev$1 has be5 giv5 ! "n pump+4#ac ,pump+ 9 a cry/al las] is g5]ally a*iev$ by plac+ ! ruby rod )9 a spiral fla% lamp 7,figure #ae7 t op]ates l ^? us$ 9 high-spe$ 7/roboscopic7 photography4 ,:5 ! lamp is fla%$1 a bright beam ( r$ light em]ges f ! ruby1 %9+ out ?r\gh "o end1 :i* has be5 only p>tially silv]$4 ,illu/ration3 ,figure #ae ,a ruby las] sy/em4 ,ruby ,fla% lamp ,p>tially silv]$ end ,las] output ,p[] ,cool+ ,! duration ( ?is fla% ( r$ light is q brief1 la/+ only "s #cjj million?s ( a second1 b x is v int5se4 ,9 ! e>ly las]s1 su* a fla% rea*$ a peak p[] ( "s #aj1jjj watts4 ,:5 ,maiman's device 0 successfully built & op]at+1 a public relations exp]t 0 call$ 9 to help introduce ?is revolution>y device to ! _w4 ,he took "o look at ! las] & decid$ t x 0 too small & insignificant look+ & w\ld n photograph well4 ,look+ ar\nd ! lab1 he spott$ a l>g] las] & decid$ t t "o 0 bett]4 ,dr4 ,maiman in=m$ him 9 8 be/ sci5tific mann] t las] action _h n be5 a*iev$ ) t "o4 ,b ! _w ( promotion won out1 & ,dr4 ,maiman all[$ ! l>g] device to be photograph$ on ! assumption--or 0 x hope8--t he w\ld be able to get x to op]ate 9 ! future4 7,he did47 ,! device %[n 9 ,figure #af is ! true fir/ las]4 ,! all-important cry/al rod is se5 at ! c5t]4 ,^! cry/als1 incid5tally1 mu/ be q free ( extrane\s mat]ial2 h5ce !y are artificially 8gr[n01 z %[n 9 ,figure #ag4 ,! s+le l>ge cry/al is =m$ z x is pull$ sl[ly f ! 8melt01 aft] :i* x is gr\nd to size & poli%$4 ,illu/ration3 ,figure #af ,dr4 ,maiman's fir/ las]4 ,output 0 #aj1jjj watts4 ,illu/ration3 ,figure #ag ,an exotic cry/al ( ! g>net family is 8gr[n0 f a melt at a temp]ature ( #cdjj;,f4 ,,las+--,a ,,new ,,^w ,n[ we c beg9 to put toge!r ! v>i\s processes & equipm5t we h be5 discuss+ sep>ately4 ,p]haps ! be/ way to d ?is is to look aga9 at ! ^w las] & recall its mean+3 light amplification by stimulat$ emission ( radiation4 ,our objective is to create a p[]ful1 n>r[1 coh]5t beam ( light4 ,let u see h[ to d ?is4 ,9 ,figure #ah we imag9e a las] cry/al conta9+ _m atoms 9 ! gr\nd /ate 7:ite dots7 & a few 9 ! excit$ /ate 7black dots74 ,pump+ light 7wavy arr[s 9 a7 raises mo/ ( ! atoms to ! excit$ /ate1 creat+ ! requir$ population inv]sion4 ,illu/ration3 ,figure #ah ,sequ5ce ( op]ations 9 a solid cry/al las]4 7a7 ,pump+ light raises _m atoms to excit$ /ate4 7b7 ,las+ beg9s :5 a photon is spontane\sly emitt$ along ! axis ( ! cry/al4 ,?is /imulates o!r atoms 9 its pa? to emit4 7c7 ,! result+ wave is reflect$ back & =? _m times betwe5 ! ends ( ! cry/al & builds 9 int5sity until f9ally x fla%es out ( ! p>tially silv]$ end4 7a7 ,ruby cry/al ,pump+ light ,atom 9 gr\nd /ate ,excit$ atom ,p>tial reflect+ mirror ,full reflect+ mirror 7b7 ,excit$ atom emits photon p>allel to axis 7c7 ,las+ beg9s :5 an excit$ atom spontane\sly emits a photon p>allel to ! axis ( ! cry/al 7b74 7,photons emitt$ 9 o!r directions m]ely pass out ( ! cry/al47 ,! photon /imulates ano!r atom 9 its pa? to contribute a second photon1 9 /ep1 & 9 ! same direction4 ,?is process cont9ues z ! photons are reflect$ back & =? betwe5 ! ends ( ! cry/al4 7,we might ?9k ( lone soldi]s fall+ into /ep ) a column ( m>*+ m547 ,! beam builds up until1 :5 amplification is great en\gh 7c71 x fla%es out ?r\gh ! p>tially silv]$ mirror at ! "r--a n>r[1 p>allel1 conc5trat$1 coh]5t beam ( light1 ready =4444 ,,"s ,,int]e/+ ,,applications ,application ( las]s c be divid$ into two broad categories3 7#a7 comm]cial1 indu/rial1 milit>y1 & m$ical uses1 & 7#b7 sci5tific rese>*4 ,9 ! fir/ case1 las]s are us$ to d some?+ t has be5 done 9 ano!r way up to n[ 7b n z well74 ,sometimes a las] solves a p>ticul> problem4 ,= example1 "o ( ! fir/ applications 0 9 eye surg]y1 = 8weld+0 a deta*$ ret9a4 ,! las] is p>ticul>ly useful "h because las] light c p5etrate transp>5t objects su* z ! eye's l5s 7,figure #ai71 elim9at+ ! ne$ to make a cut into ! eye4 ,illu/ration3 ,figure #ai ,diagram ( human eye %[+ las] beam focus$ on ret9a4 ,cornea ,l5s ,optic ,n]ve ,beam angle ,fovea c5tralis ,iris ,image ,ret9a ,surgeons h long want$ a bett] te*nique = treat+ extremely small areas ( tissue4 ,a las] beam1 focus$ into a small spot1 p]=ms p]fectly z a lilliputian surgical knife4 ,an additional advantage is t ! beam1 be+ ( su* high int5sity1 c also /]ilize or caut]ize tissue z x cuts4 ,! n>r[ness ( ! las] beam has made x ideal = applications requir+ accurate alignm5t4 ,p]haps ! ultimate "h is ! #b-mile-long l9e> accel]ator built by ,/an=d ,univ]sity = ! ,unit$ ,/ates ,atomic ,en]gy ,commission4 8,arr[-/raight0 w\ld n h be5 ne>ly good en\gh to assure expect$ p]=mance4 ,a las] beam 0 ! only te*nique t c\ld accompli% ! incr$ible task ( keep+ ! in* bore ( ! accel]ator /raight along its #b-mile l5g?4 ,a remote monitor+ sy/em1 bas$ on ! same las] beam1 tells op]ators :5 a section ( ! accel]ator has %ift$ out ( l9e 7due = example to small e>? movem5ts7 by m ?an ab\t _/ in*--& id5tifies ! section4#ad ,figure #bj %[s ! #b-mile-long 8kly/ron gall]y0 t g5]ates ! p[] = kick+ ! high-en]gy p>ticles d[n ! tube4 ,! gall]y p>allels ! accel]ator h\s+ & lies #be feet b5ea? x 7,figure #ba74 ,! l>ge tube h\ses ! optical alignm5t sy/em & supports ! small] accel]ator tube above4 ,t>get patt]ns dropp$ into ! l>ge tube at select$ po9ts produce an int]f]5ce patt]n at ! f> end ( ! tube simil> to ! "o 9 ,figure #ac4 ,precise alignm5t ( ! tube is a*iev$ by aim+ ! las] at ! c5t] dot ( ! patt]n4 ,!n ! section t is out ( l9e is physically mov$ until ! dot appe>s 9 ! prop] place at ! o!r end ( ! tube4 ,x is ! extreme coh]5ce ( ! las] beam t makes ?is te*nique possible4 ,hav+ he>d t las] light has bor$ ?r\gh /eel & is be+ us$ 9 micr[eld+1 "s h ask$ :e!r ! las] w ev] be us$ to weld bridge memb]s & o!r /ructural gird]s4 ,?is is miss+ ! :ole po9t ( ! las]3 ,x w\ld be l wa%+ y\r floor ) a too?bru% 7ev5 "o ) extra /iff bri/les76 ,!re w\ld be no advantage to us+ las]s = l>ge-scale weld+2 pres5t equipm5t = ?is op]ation is q satisfactory & f> less wa/eful ( input p[]4 ,! s5sible approa* is to use las]s :]e exi/+ processes leave some?+ to be desir$4 ,until ! adv5t ( ! las]1 = example1 !re 0 no good way to weld wires #j4jja in* 9 diamet]4 ,nor 0 !re a good way to bore ! t9y hole 9 a diamond t is us$ z a die = draw+ su* f9e wire4 ,x us$ to take #b days to drill a s+le diamond4 ,) las] light ! op]ation takes #b m9utes--& !re is no problem ) rapid we> ( a cutt+ tool4 ,s mu* = ! fir/ category ( application4 ,9 ! second category1 namely use ( ! las] z a sci5tific tool1 we ent] a m !oretical doma94 ,"h we use coh]5t light z an ext5sion ( ourselves1 to probe into & to look at ! _w ar\nd u4 ,illu/ration3 ,figure #bj ,a las] beam 0 us$ 7& cont9ues to be us$7 = precise alignm5t ( ,/an=d ,univ]sity's #b-mile-long l9e> accel]ator4 ,?is view %[s ! abovegr\nd portion dur+ con/ruction4 ,mu* exp]im5tal sci5ce is a matt] ( cool+1 heat+1 gr9d+1 squeez+1 or o!rwise abus+ matt] to see h[ x w react4 ,) ea* new tool--ultrafa/ c5trifuges1 high- & l[-pressure & extreme-temp]ature *amb]s1 int5se magnetic fields1 atomic accel]ators & s on--m has be5 le>n$ ab\t ?is /ill-puzzl+ _w4 ,s9ce coh]5t light is some?+ new1 we c d ?+s to matt] t h n be5 done be=e1 & see h[ x reacts4 ,! las] is be+ us$ to inve/igate _m problem areas 9 biology1 *emi/ry1 & physics4 ,= example1 s\nd waves ( extremely high frequ5cy c be g5]at$ 9 matt] by subject+ x to las] light4 ,^! int5se vibrations may h pr(\nd effects on mat]ials4 ,illu/ration3 ,figure #ba ,subt]ranean view ( ,/an=d accel]ator h\s+4 ,alignm5t optics 7las] sy/ems7 are h\s$ 9 ! l>ge tube1 :i* also acts z support = ! small] accel]ator tube above x4 ,illu/ration3 ,figure #bb ,las] beam spot z obs]v$ at ! end ( ! accel]ator4 ,9 ! *emical field ! %>p beam & mono*romatic en]gy ( ! las] hold great promise 9 ! exploration ( molecul> /ructure & ! nature ( *emical reactions4 ,*emical reactions usually are set (f by heat1 agitation1 electricity1 or o!r broadly appli$ means4 ,none ( ^! en]giz]s all[ ! f9e control t ! las] beam does4 ,its extremely f9e beam c be focus$ to a t9y spot1 ?us all[+ *emical activity to be p9po9t$4 ,b !re is a second advantage3 ,! mono*romaticity ( coh]5t light also makes x possible to control ! en]gy 79 addition to ! int5sity7 ( ! beam accurately by simply v>y+ ! wavel5g?4 ,?us x may be possible1 = in/ance1 to cause a reaction 9 "o gr\p ( molecules & n 9 ano!r4 ,"o application 9 *emi/ry t holds great promise is ! use ( las] en]gy = caus+ specific *emical reactions su* z ^? involv$ 9 ! mak+ ( pla/ics4 ,bell ,telephone ,laboratory sci5ti/s h *ang$ ! /yr5e monom] 7a 8raw0 pla/ic mat]ial7 to its f9al /ate1 poly/yr5e1 9 ?is way4 ,! success ( ^! & simil> exp]im5ts else:]e op5s = exploration a va/ area ( molecul> ph5om5a4 ,9 ano!r sci5tific application1 ! las] is be+ us$ m & m z a tea*+ tool4 ,coh]5ce is a concept t =m]ly _h to be demon/rat$ by diagrams1 =mulas1 & inf]5ce f exp]im5ts4 ,! las] makes x possible to see coh]5ce 89 action01 along ) _m ( ! physical effects t result f x4 ,su* ph5om5a z diffraction1 int]f]5ce1 ! s-call$ ,airy disc patt]ns1 & spatial h>monics1 always difficult to demon/rate to /ud5ts 9 ! ab/ract1 c n[ be se5 q concretely4 ,o!r int]e/+ ?+s c also be se5 m pla9ly n[4 ,at ! ,los ,alamos ,sci5tific ,laboratory1 las] light is be+ us$ to 8look0 at plasmas2 ! result ( "o su* look is %[n 9 ,figure #bc4 ,plasmas are ioniz$ gase\s mixtures4 ,_! /udy lies at ! he>t ( a con/ant se>* by atomic sci5ti/s = a self-su/a9$1 controll$ fusion reaction t c be us$ to provide useful !rmonucle> p[]4 ,?is k9d ( reaction provides ! almo/ unlimit$ en]gy 9 ! sun & o!r />s4 ,x is m effici5t & releases less radioactivity ?an ! o!r pr9cipal nucle> process1 fission1 :i* is us$ 9 atomic-electric p[] plants4#ae ,illu/ration3 ,figure #bc ,%ad[graph ( deut]ium dis*>ge tak5 9 las] light4 ,turbul5ce ( ! plasma is cle>ly se54 ,we/+h\se ,electric ,corporation sci5ti/s1 on ! o!r h&1 h us$ ! conc5trat$ en]gy ( ! las]1 n to look at1 b to produce a plasma 7,figure #bd74 ,!y bla/$ an alum9um t>get ! size ( a p9head ) a las] beam1 !reby vaporiz+ x & creat+ a plasma4 ,! calculat$ temp]ature 9 ! electrically *>g$ gas 0 #c1jjj1jjj c5tigrade4 ,?is is pretty hot1 b /ill n hot en\gh = a !rmonucle> reaction4 ,illu/ration3 ,figure #bd ,plasma heat+ by las] light4 ,diamagnetic loop ,las] beam ,vacuum *amb] ,magnetic field ,magnetic coils ,electro/atic probe ,plasma ,l5s ,mirror ,to vacuum pump ,cam]a ,! temp]ature ( a plasma necess>y to su/a9 a !rmonucle> reaction is s high 7above #aj1jjj1jjj;,c7 t any mat]ial is vaporiz$ in/antly on com+ into contact ) x4 ,! only means develop$ s f> to conta9 ! plasma is an int5se magnetic field1 or 8magnetic bottle02 conta9m5t has be5 accompli%$ = only a few ?\s&?s ( a second at mo/4 ,! objective ( ! ,we/+h\se rese>*1 :i* 0 support$ by ! ,atomic ,en]gy ,commission1 0 to /udy 9 detail ! int]action ( ! plasma ) a magnetic field4 ,we d n h room to describe m applications 9 detail1 b x may be int]e/+ to li/ a few o!r uses ( las]s--"s comm]cial & "s /ill exp]im5tal3 --,e>?quake pr$iction4 --,measurem5t ( 8tides0 9 ! e>?'s cru/ "u ! sea4 --,las] gyroscopes4 --,highly accurate velocity measurem5t 7useful 9 c]ta9 assembly l9e & cont9u\s manufactur+ processes74 --,scann] = analyz+ photographs ( bubble *amb] tracks & a/ronomical ph5om5a4 --,comput] output & /orage sy/ems2 p]haps ev5 complete optical data process+ sy/ems4 --,lightn+-fa/ pr9t+ devices4 --,high-spe$ photography 7,figure #be74 --,missile track+ & accurate alignm5t ( ant5nas4 --,automatic flaw spott] = big radio ant5nas4 --,aircraft l&+ aid = poor wea!r conditions4 --,fa/1 pa9less d5tal drill4 --,canc] rese>*4 ,illu/ration3 ,figure #be ,tw5ty-two calib] bullet & its %ock wave are photograph$ f ! image produc$ by a d\bly expos$ las] hologram4 ,! orig9al hologram 0 expos$ twice by a ruby las] )9 half a ?\s&? ( a second z ! bullet sp$ pa/ at #b times ! spe$ ( s\nd4 ,a ,,multitude ,,( ,,las]s ,x is almo/ self-evid5t t no s+le device1 ev5 "o z incr$ible z ! las]1 c\ld accompli% all ! feats m5tion$ 9 ! prec$+ p>agraphs4 ,aft] all1 "s ( ^! applications require high p[] b n extremely high mono*romaticity1 :ile 9 o!rs ! rev]se may be true4 ,yet1 by its v nature1 any las] produces a beam ) "o1 or at ! mo/ a few1 wavel5g?s1 & _m diff]5t mat]ials w\ld be ne$$ to provide ! _m diff]5t wavel5g?s requir$ = all ! tasks li/$4 ,also1 ! fir/ las] 0 a puls$ device4 ,light en]gy 0 pump$ 9 & a bullet ( en]gy em]g$ f x4 ,!n ! :ole process _h to be repeat$4 ,puls$ op]ation is f9e = spot-weld+ & = applications su* z rad>-type rangef9d+1 :]e pulses ( en]gy are normally us$ anyway4 ,) las]s small] objects c be detect$ ?an :5 us+ ! usual micr[aves4 ,b a puls$ process is n useful = communications4 ,9 o!r words1 puls+ is good = c]ta9 applications b n = o!rs4 ,& ( c\rse solid cry/als are difficult to manufacture4 ,h5ce1 x 0 natural = las] pione]s to look hopefully at gases4 ,gas las]s w\ld be easi] to make--simply fill a glass tube ) ! prop] gas & seal x4 ,b o!r advantages w\ld accrue4 ,= "o ?+ ! relatively sp>se population ( emitt+ atoms 9 a gas provides an almo/ ideally homog5e\s m$ium4 ,t is1 ! emitt+ atoms 7correspond+ to *romium 9 ! ruby cry/al7 are n 8contam9at$0 by ! lattice or ho/ atoms4 ,s9ce only active atoms ne$ be us$1 ! frequ5cy coh]5ce ( a gas las] w\ld probably be ev5 bett] ?an t ( ! cry/al las]1 !y reason$4 ,x 0 less ?an a ye> aft] ! developm5t ( ! ruby las] t ,ali ,javan ( ,bell ,telephone ,laboratories propos$ a gas las] employ+ a mixture ( helium & neon gases4 ,?is 0 an +5i\sly contriv$ p>tn]%ip :]eby "o gas did ! en]giz+ & ! o!r did ! amplify+4 ,gas las]s n[ utilize _m diff]5t gases = diff]5t wavel5g? outputs & p[]s & provide ! 8pure/0 light ( all4 ,an additional advantage is t ! optical pump+ light c\ld be disp5s$ )4 ,an input ( radio waves ( ! prop] frequ5cy did ! job v nicely4 ,b mo/ significant ( all1 ,javan's gas las] provid$ ! fir/ cont9u\s output4 ,?is is commonly ref]r$ to z ,,cw 7cont9u\s wave7 op]ation4 ,! di/9ction betwe5 puls$ & ,,cw op]ation is l ! diff]5ce betwe5 bak+ "o loaf ( bread at a "t & putt+ ! +r$i5ts 9 "o end ( a bak+ ma*9e & hav+ a cont9u\s loaf em]ge at ! o!r4 ,:5 a non-exp]t ?9ks ( a las]1 he is apt to ?9k ( p[]--bl9d+ fla%es ( en]gy--z illu/rat$ 9 ,figure #bf4 ,z we "k1 ?is is only a small "p ( ! capability ( ! las]4 ,nev]!less1 s9ce las]s are (t5 specifi$ 9 t]ms ( p[] output x may be well to discuss ?is aspect4 ,! two units g5]ally us$ are j\les & watts4 ,y are famili> ) a watt & h an idea ( its magnitude3 ?9k1 = example1 ( a #ae-watt or a #aej-watt bulb4 ,a watt is a unit ( p[]2 x is ! rate at :i* 7electrical7 "w is be+ done4 ,illu/ration3 ,figure #bf ,high p[] is demon/rat$ z a las] beam bla/s ?r\gh metal *a94 ,! j\le is a unit ( en]gy & c be ?\ght ( z ! total capacity to d "w4 ,"o j\le is equival5t to #a watt-second1 or #a watt appli$ = #a second4 ,b x c also mean a #aj-watt bur/ ( las] light la/+ #j4a second1 or a billion watts la/+ a billion? ( a second4 ,9 g5]al1 ! cry/al 7ruby7 las]s are ! mo/ p[]ful1 al?\gh o!r rec5tly introduc$ mat]ials1 su* z liquids 7see ,figure #bg7 & specially prep>$ glass1 are provid+ competition4 ,) prop] auxili>y equipm5t1 bur/s ( sev]al billion watts h be5 a*iev$2 b ! bur/ la/s only ab\t #ajj million?s ( a second4 ,= c]ta9 uses1 t's j :at is want$3 a highly conc5trat$ bur/ ( en]gy t does its "w )\t giv+ ! mat]ial be+ 8%ot0 a *ance to heat up & spread ! en]gy1 p]haps damag+ adjac5t areas4 ,illu/ration3 ,figure #bg ,active sub/ance = a mod]n liquid las] is made 9 an uncomplicat$ #aj-m9ute proc$ure4 ,blui% p[d] ( ! r>e e>?1 neodymium1 is dissolv$ 9 a solution ( sel5ium oxy*loride & seal$ 9 a glass tube4 ,s9ce ! j\le gives a measure ( ! total en]gy 9 a las] bur/ x is n applicable to ,,cw output4 ,p[] 9 ?is area began l[--9 ! milliwatt 7"o ?\s&? ( a watt7 region--b has be5 creep+ up /eadily4 ,a rec5t gas las] utiliz+ c>bon dioxide has already rea*$ #eej watts ( cont9u\s infr>$ radiation4 ,?is is ! giant #dd-;foot] %[n 9 ,figure #bh4 ,an advantage ( gas 7& liquid7 las]s is t !y c be made j ab\t z l>ge z "o wi%es4 ,by way ( comp>ison1 ! smalle/ gas las] 9 use is %[n 9 ,figure #bi4 ,illu/ration3 ,figure #bh ,a giant #dd-;foot gas las] produces #eej watts ( cont9u\s p[] & is expect$ to rea* #ajjj watts4 ,gl[+ ( ! tube comes f gas dis*>ge1 n f las] light1 :i* is 9 ! infr>$ region & _c be se54 ,"o ( ! lea/ satisfactory aspects ( ! las] has be5 its notori\sly l[ effici5cy4 ,= a :ile ! be/ t c\ld be accompli%$ 0 ab\t #a4 ,t is1 a hundr$ watts ( light _h to be put 9 to get #a watt ( coh]5t light out4 ,9 gas las]s ! effici5cy 0 ev5 l[]1 rang+ f #j4ja to #j4a4 ,9 gas las]s ?is 0 no great problem s9ce high p[] 0 n ! objective4 ,b ) ! high-p[] solid las]s1 pump+ p[] c\ld be a major und]tak+4 ,a high-p[] las] pump built by ,we/+h\se ,rese>* ,laboratories h&les #gj1jjj j\les4 ,9 m famili> t]ms1 ! peak p[] input :ile ! pump is on is ab\t #ajj1jjj1jjj watts4 ,= a brief in/ant ?is is r\ghly equal to all ! electrical p[] ne$s ( a city ( #ajj1jjj p4 ,two relatively new developm5ts h *ang$ ! effici5cy levels4 ,"o1 ! c>bon dioxide gas las]1 is q effici5t1 ) ! figure hav+ pass$ #ae4 ,! second is ! injection1 or semiconductor las]1 9 :i* effici5cies ( m ?an #dj h be5 obta9$4 ,unless un=ese5 difficulties arise ?is figure is expect$ to cont9ue to rise to a !oretical maximum ( close to #ajj4 ,illu/ration3 ,figure #bi ,a m9iature gas las] produces cont9u\s output 9 visible r$ region4 ,! semiconductor las] is to solid & gas las]s :at ! transi/or 0 to ! vacuum tube2 all ! functions ( ! las] h be5 pack$ into a t9y semiconductor cry/al4 ,9 ?is case1 electrons & 8holes0 7vacancies 9 ! cry/al /ructure t act l positive *>ges7 accompli% ! job done by excit$ atoms 9 ! o!r types4 ,t is1 :5 !y are /imulat$ !y fall f upp] en]gy /ates to l[] ones1 & emit coh]5t radiation 9 ! process4 ,aside f ?is ! pr9ciple ( op]ation is ! same4 ,! device itself1 h[ev]1 is va/ly diff]5t4 ,= "o ?+ x is ab\t ! size ( ?is lett] 8o0 7,figure #cj74 ,= ano!r1 x is self-conta9$2 s9ce x c conv]t electric curr5t directly into las] light--! fir/ "t ?is has be5 possible--an ext]nal pump+ s\rce is n requir$4 ,?is makes x possible to modulate ! beam by simply modulat+ ! curr5t4 7,a diff]5t approa* has be5 to modulate a magnetic field ar\nd ! device4 ,?is1 x turns out1 c also be done ) "s new] solid cry/al las]s47 ,an additional advantage (f]$ by ! semiconductor las] is simplicity4 ,!re are no gases or liquids to deal )1 no glassw>e to break1 & no mirrors to align4 ,al?\gh x w n deliv] high p[]1 x c already deliv] en\gh ,,cw p[] = c]ta9 communications purposes4 ,its simplicity1 effici5cy1 & light weight make x ideal = use 9 space4 ,illu/ration3 ,figure #cj ,a t9y injection las] works 9 infr>$ region4 ,! beam is visible because photo 0 tak5 ) infr>$ film4 ,! las] itself is a t9y cry/al ( gallium ars5ide inside ! metal m\nt be+ held betwe5 ! f+]s4 ,,communications ,future deep space missions are expect$ to require extremely high data transmission rates 7on ! ord] ( a million bits#af p] second7 to relay ! huge quantities ( sci5tific & eng9e]+ in=mation ga!r$ by ! spacecraft4 ,high] data rates are necess>y to increase bo? ! total capacity & ! spe$ ( transmission4 ,by comp>ison1 ! ,m>9]-#d spacecraft t s5t back ,,tv pictures ( ,m>s _h a data rate ( only eight bits p] second--a hundr$ ?\s& times too small = future missions4 ,! use ( las]s w\ld mean t results c\ld be transmitt$ to e>? 9 seconds in/ead ( ! #h h\rs x took = ! photos to be s5t f ,m>9]-#d4 ,"o ( ! problems to be solv$ 9 us+ las]s = deep space communication1 oddly en\gh1 is t ( po9t+ accuracy4 ,s9ce ! beam ( las] en]gy is n>r[1 x w\ld be possible = ! radiation to miss ! e>? altoge!r & be lo/ entirely unless ! las] 7 po9t$ at ! receiv] ) extreme precision4 ,aim+ a gun at a t>get #ej y>ds away is "o ?+2 aim+ a las] f an unmann$ spacecraft #ajj million miles away is q ano!r4 ,x is believ$1 h[ev]1 t pres5t te*niques c cope ) ! problem4 ,ano!r peculi>ity ( las] communication is t x w probably be accompli%$ fa/] & m readily 9 space ?an "h on e>?4 ,p[]ful ?\gh las] light may be1 x is light & is !re=e imp$$ to "s ext5t by our atmosph]e ev5 "u good conditions4 ,data transmissions ( #bj & #cj miles h already be5 accompli%$ 9 good wea!r ) las]s4 ,b if y h ev] tri$ to =ce a se>*light beam or %9e automobile headlights ?r\gh heavy fog1 ra91 or sn[1 y w appreciate ! magnitude ( ! problem "u ^! conditions4 ,! use ( infr>$ frequ5cies helps to "s ext5t1 s9ce infr>$ is some:at m p5etrat+1 b ! poor-wea!r problem is a s]i\s "o4 ,a possible solution is ! use ( 8light pipes01 simil> to ! wave guides already 9 use = c]ta9 micr[ave applications ov] %ort di/ances4 ,b z (t5 happ5s1 new developm5ts create new ne$s2 h[1 = example1 c we get ! las] beam to /ay c5t]$ 9 ! pipe & foll[ curves8 ,a s]ies ( closely spac$ l5ses1 ab\t #ajjj p] mile1 probably w\ld accompli% ?is1 b too mu* light w\ld be lo/ by scatt]+ f ! _m l5s surfaces4 ,sci5ti/s are exp]im5t+ ) a new k9d ( 8l5s01 "o t uses v>iations 9 ! d5sity ( gases to focus & guide ! beam automatically4 ,s9ce !re are no surfaces 9 ! pa? ( ! light beam1 & s9ce ! gas is transp>5t & free ( turbul5ce1 ! las] beam is n appreciably weak5$ or scatt]$ z x travels ?r\gh ! pipe4 ,illu/ration3 ,figure #ca ,las] light beam be+ guid$ ?r\gh a 8light pipe0 by a gas 8l5s04 ,heat+ coil 7l[] left7 or mixture ( gases 7l[] "r7 are two possible ways ( ma9ta9+ prop] d5sity gradi5t 9 ! gas4 ,figure #ca %[s h[ ! gas focus+ pr9ciple might be us$ to guide a beam ?r\gh a curv+ pipe4 ,! %ad+ repres5ts ! d5sity ( ! gas4 ,sev]al means h be5 develop$ to keep ! gas d5s] 9 ! c5t] ?an ar\nd ! outside4 ,:5 ! pipe curves1 ! light beam />ts mov+ (f ! axis ( ! pipe4 ,! gas !n acts l a prism1 deflect+ ! light beam 9 ! direction ( ! curvature ( ! 8prism04 ,9 communication betwe5 di/ant space & e>?1 a light pipe might be a little cumb]some2 h5ce x may prove necess>y to set up an int]m$iate orbit+ relay /ation t w1 p>ticul>ly 9 cases ( poor wea!r1 int]cept ! incom+ las] beam & conv]t x to radio frequ5cies t c p5etrate our atmosph]e ) great] reliability4 ,p[]+ space-borne las]s w1 ( c\rse1 be a problem4 ,inde$ "o ( ! major unsolv$ problems 9 production ( spacecraft & long-t]m satellites is ! provision ( an adequate supply ( p[]4 ,fuel cells & sol> cells h help$ b d n give ! :ole answ]4#ag ,"o o!r approa* has already be5 develop$3 a sun-pump$ las]4 ,sunlight focus$ onto ! side ( ! las] 7see ,figure #cb7 provides ! pump+ p[]1 enabl+ ! device to put out #a watt ( cont9u\s infr>$ radiation1 en\gh = special space applications4 ,desc5d5ts ( ?is device c\ld produce visible light if ?is is deem$ desirable4 ,ano!r approa*1 us+ *emical las]s1 is ev5 m intrigu+ & may h great] consequ5ces4 ,*emical las]s w d]ive _! en]gy f _! int]nal *emi/ry r ?an f ! outside4 ,a mixture ( two *emicals may be all t is ne$$ to initiate las] action abo>d a spacecraft or satellite4 7,*emical las]s also (f] ! promise ( ev5 great] conc5trations ( p[] ?an h be5 a*iev$ h]et(ore1 :i* may make !m useful 9 plasma rese>*47 ,) all ^! possibilities1 x may /ill be t spacecraft w ne$ m p[] ?an is available on bo>d4 ,! n>r[ beam ( ! las] (f]s "o m fasc9at+ possibility1 especially 9 ! case ( satellites relatively ne> e>?4 ,! light ( a las] might actually be us$ to beam en]gy to a receiv]1 ei!r = imm$iate use or /orage4 ,x w\ld !n become possible to 8refuel0 satellites at w1 giv+ !m mu* great] capabilities4 ,if available las] p[] is great en\gh1 las] beams might ev5 be us$ to pu% satellites back into _! prop] orbits :5 !y beg9 to w&] (f c\rse1 z !y almo/ inv>iably d aft] a :ile4 ,illu/ration3 ,figure #cb ,arti/'s r5d]+ ( sun-pump$ las] z x w\ld op]ate 9 space4 ,! sun's rays are collect$ by a p>abolic reflector & are focus$ on ! las]'s surface by two cyl9drical mirrors4 ,sun ,p>abolic ,collector ,hyp]bolic-cyl9dric second>y mirror ,semi-circul>-cyl9dric t]ti>y mirror ,las] beam ,a ,,las] ,,9 ,,y\r ,,future8 ,atomic en]gy1 only a sci5tific dream a few %ort ye>s ago1 is n[ provid+ ne$$ p[] 9 _m p>ts ( ! _w4 ,9 ! same way1 ! las]1 also an atomic ph5om5on1 has made its way out ( ! laboratory & into ! fields ( m$ic9e1 comm]ce1 & indu/ry4 ,if x hasn't t\*$ y\r life z yet1 y ne$ only be pati5t4 ,x w4 ,inde$ ! mo/ excit+ probability ( all is t las]s und\bt$ly w *ange our lives 9 ways we _c ev5 conceive ( n[4 ,illu/ration3 ,figure #cc ,t9y hole drill$ 9 pap] clip demon/rates rem>kable capability ( las] beam4 ,pap] clip is #a in*es long4 ,hole 7top7 0 drill$ by ! las] micr[eld] %[n 9 ,figure #a4 ,,sugge/$ ,,ref]5ces ,books ,,abc's ( ,mas]s & ,las]s1 ,allan ,h4 ,lytel1 ,h[>d ,w4 ,sams & ,company1 ,inc41 ,publi%]s1 ,indianapolis1 ,indiana #dfbjf1 #aiff1 #if pp41 #b4be4 ,! ,las]3 ,light ,t ,nev] ,0 ,be=e1 ,b5 ,patrusky1 ,dodd1 ,mead & ,company1 ,new ,york #ajjaf1 #aiff1 #abh pp41 #c4ej4 ,mas]s & ,las]s1 ,manfr$ ,bro!rton1 ,mc,graw-,hill ,book ,company1 ,new ,york #ajjcf1 #aifd1 #bbd pp41 #h4ej4 ,mas]s & ,las]s1 ,h4 ,ar?ur ,kle91 ,j4 ,b4 ,lipp9cott ,company1 ,philadelphia1 ,p5nsylvania #aiaje1 #aifc1 #ahd pp41 #c4ie4 ,! ,/ory ( ! ,las]1 ,john ,m4 ,c>roll1 ,e4 ,p4 ,dutton & ,company1 ,inc41 ,new ,york #ajjjc1 #aifd1 #aha pp41 #c4ie4 ,quantum ,electronics3 ,! ,fundam5tals ( ,transi/ors & ,las]s1 ,john ,r4 ,pi]ce1 ,d\bl$ay & ,company1 ,inc41 ,new ,york #ajjag1 #aiff1 #ach pp41 #a4be4 ,las]s & ,_! ,applications1 ,kurt ,r4 ,/ehl+1 ,! ,_w ,publi%+ ,company1 ,clevel&1 ,ohio #ddajb1 #aiff1 #aib pp41 #f4jj4 ,und]/&+ ,las]s & ,mas]s1 ,/anley ,le9woll1 ,hayd5 ,book ,companies1 ,new ,york #ajjaa1 #aifd1 #if pp41 #a4ie4 ,atomic ,light3 ,las]s1 ,ri*>d ,b4 ,nehri*1 ,jr41 ,gl5n ,i4 ,voran1 & ,norman ,f4 ,dessel1 ,/]l+ ,publi%+ ,company1 ,inc41 ,new ,york #ajjaf1 #aifg1 #acf pp41 #c4ie4 ,articles--,g5]al & ,hi/orical ,advances 9 ,optical ,mas]s1 ,a4 ,l4 ,s*awl[1 ,sci5tific ,am]ican1 #bji3 #cd 7,july #aifc74 ,! ,evolution ( ! ,physici/'s ,picture ( ,matt]1 ,p4 ,a4 ,m4 ,dirac1 ,sci5tific ,am]ican1 #bjh3 #de 7,may #aifc74 ,fill+ 9 ! ,blanks 9 ! ,las]'s ,spectrum1 ,f4 ,m4 ,johnson1 ,electronics1 #ci3 #hb 7,april #ah1 #aiff74 ,! ,amateur ,sci5ti/--,h[ a p]sev]+ amateur c build a gas las] 9 ! home1 ,c4 ,l4 ,/ong1 ,sci5tific ,am]ican1 #baa3 #bbg 7,septemb] #aifd74 ,! ,amateur ,sci5ti/--,homemade ,las]1 ,c4 ,l4 ,/ong1 ,sci5tific ,am]ican1 #bac3 #ajh 7,decemb] #aife74 ,! ,amateur ,sci5ti/--,h[ to make holograms & exp]im5t ) !m or ) ready-made holograms1 ,c4 ,l4 ,/ong1 ,sci5tific ,am]ican1 #baf3 #abb 7,febru>y #aifg74 ,! 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,sophomore ,laboratory1 ,r4 ,h4 ,webb1 ,am]ican ,j\rnal ( ,physics1 #cf3 #fb 7,janu>y #aifh74 ,las] ,light1 ,a4 ,l4 ,s*awl[1 ,sci5tific ,am]ican1 #bai3 #abj 7,septemb] #aifh74 ,! ,modulation ( ,las] ,light1 ,d4 ,f4 ,nelson1 ,sci5tific ,am]ican1 #bah3 #ag 7,june #aifh74 ,articles--,special ,subjects ,biological ,effects ( ,high ,peak ,p[] ,radiation1 ,s4 ,f9e et al41 ,life ,sci5ces1 #c3 #bji 7#aifd74 ,! ,int]action ( ,light ) ,light1 ,j4 ,a4 ,giordma9e1 ,sci5tific ,am]ican1 #baj3 #ch 7,april #aifd74 ,*emical ,las]s1 ,george ,c4 ,pim5tal1 ,sci5tific ,am]ican1 #bad3 #cb 7,april #aiff74 ,color ,las] ,/ores ,data1 ,j4 ,eb]h>t1 ,sci5ce ,news1 #ij3 #ea 7,july #bc1 #aiff74 ,communication by ,las]1 ,/ew>t ,e4 ,mill]1 ,sci5tific ,am]ican1 #bad3 #ai 7,janu>y #aiff74 ,guidel9es = ,select+ ,las] ,mat]ials1 ,r4 ,h4 ,hosk9s1 ,electronic ,design1 #ac3 ,m#bi 7,july #ai1 #aife74 ,holography3 ,! ,picture ,looks ,good1 ,j4 ,blum1 ,electronics1 #ci3 #aci 7,april #ah1 #aiff74 ,h[ ,dang]\s ,are ,las]s81 ,l4 ,h4 ,dulb]g]1 ,electronics1 #ce3 #bg 7,janu>y #bf1 #aifb74 ,injection ,las]s1 ,r4 ,w4 ,keyes1 ,indu/rial ,rese>*1 #f3 #df 7,octob] #aifd74 ,las] ,pot5tial 9 ,deep-,space ,l9k ,gr[s1 ,b4 ,mill]1 ,aviation ,week & ,space ,te*nology1 #hd3 #ga 7,janu>y #ca1 #aiff74 ,las] ,ret9al ,photocoagulator1 ,n4 ,s4 ,kapany et al41 ,appli$ ,optics1 #d3 #eag 7,may #aife74 ,las] ,weld+ 9 ,electronic ,circuit ,fabrication1 ,j4 ,p4 ,epp]son1 ,electrical ,design ,news 7,,edn71 #aj3 #h 7,octob] #aife74 ,! ,light ,t ,slices ,in* into ,million?s1 7use ( int]f]ometry 9 indu/ry71 ,/eel1 #aeh3 #ch 7,febru>y #bh1 #aiff74 ,! ,optical ,het]odyne--,key to ,advanc$ ,space ,signal+1 ,s4 ,jacobs1 ,electronics1 #cf3 #bi 7,july #ab1 #aifc74 ,photography by ,las]1 ,e4 ,n4 ,lei? & ,j4 ,upatnieks1 ,sci5tific ,am]ican1 #bab3 #bd 7,june #aife74 ,liquid ,las]s1 ,alex&] ,lempicki & ,h>old ,samelson1 ,sci5tific ,am]ican1 #baf3 #ha 7,june #aifg74 ,plasma ,exp]im5ts ) a #egj-k,j ,!ta-,p9*1 ,f4 ,c4 ,yahoda1 et al41 ,j\rnal ( ,appli$ ,physics1 #ce3 #bcea 7,augu/ #aifd74 ,a ,sun-,pump$ ,,cw ,"o-,watt ,las]1 ,c4 ,g4 ,"y1 ,appli$ ,optics1 #e3 #iic 7,june #aiff74 #c-;,d ,image ,made at ,home1 ,sci5ce ,news1 #ij3 #ahe 7#aj ,septemb] #aiff74 ,scann+ ) ,las]s1 ,rob]t ,a4 ,my]s1 ,int]national ,sci5ce & ,te*nology1 #fe3 #dj 7,may #aifg74 ,booklets ,applications ( ,las]s to ,in=mation ,h&l+1 ,! ,p]k9-,elm] ,corporation1 ,norwalk1 ,connecticut #jfheb1 #aiff1 #cb pp41 free4 ,repr9t ( five talks giv5 by company p]sonnel4 ,las] ,int]f]omet]1 ,airborne ,in/rum5ts ,laboratory1 ,division ( ,cutl]-,hamm]1 ,inc41 ,de] ,p>k1 ,long ,isl&1 ,new ,york #aagbi1 #aife1 #bj pp41 free4 ,collection ( article repr9ts4 ,las]3 ,! ,new ,light1 ,bell ,telephone ,laboratories1 ,murray ,hill1 ,new ,j]sey #jgiga1 #ai pp41 free4 ,full color1 nonte*nical bro*ure pres5ts "s backgr\nd1 pr9ciples1 & applications ( ! las]4 ,illu/ration3 ,argon las]1 :i* emits high-p[] blue-gre5 beam cont9u\sly1 has application 9 signal process+1 communications1 & spectroscopy4 ,?is unit is be+ beam$ ?r\gh prisms t sep>ate its sev]al discrete wavel5g?s ( light1 display$ on c>d at left =egr\nd4 ,,footnotes #a,sometimes ref]r$ to z h]tz 7abbreviat$ ,hz71 = ! #ai? ,c5tury ,g]man physici/ ,he9ri* ,h]tz2 #ajjj ,hz #ajjj cps4 #b;,devis$ 9 ,france & (ficially adopt$ !re 9 #agii1 ! metric sy/em uses ! met] z ! basic unit ( l5g? & has be5 propos$ = all measurem5ts 9 ?is c\ntry4 #c,nam$ = ! ,sw$i% physici/ ,&]s ,j4 ,ang/rom4 #d,! wavel5g?1 indicat$ by ! ,greek lett] 7lambda7 is relat$ to frequ5cy 7f7 9 ! proportion 79 met]s7 #cjj1jjj1jjj_/;f4 7,! numb] #cjj1jjj1jjj is ! velocity ( light 9 met]s p] second47 #e,micr[aves are radio waves ) frequ5cies above #ajjj megacycles p] second4 #f,t5 to #cj1jjj1jjj kilocycles p] second2 ?is is l[ 9 ! electromagnetic spectrum1 b n l[ 9 t]ms ( ! radio spectrum1 :i* has a l[-frequ5cy classification ( its own4 #g,primitive z e>ly radios 7 by today's /&>ds1 !y br\ght a new era to communication at ! "t4 ,unmodulat$ ,,cw 7cont9u\s wave7 transmissions & cry/al receiv]s 7 us$ to summon rescu]s 9 ! ,titanic disa/] ( #aiab1 = example4 #h;,en]gy h 7,planck's con/ant7 frequ5cy4 ,planck's con/ant is ! en]gy ( #a quantum ( radiation1 & equals #f4fbeef #aj erg-sec4 #i;,ea* photon c>ries #a quantum ( radiation en]gy1 :i* is a unit equal to ! product ( ! radiation frequ5cy & ,planck's con/ant 7see footnote page #ae74 #aj;,e9/e9 0 aw>d$ ! ,nobel ,prize 9 #aiba = 8 #aije explanation ( ! photoelectric effect 79 t]ms ( quanta ( en]gy7 & n = 8 relativity !ory4 #aa;,e9/e9's !oretical explanation applies 9 ! case ( /imulation ( a s+le atom4 ,9 practical /imulation1 directionality is enhanc$ by /imulat+ _m atoms 9 phase4 #ab;,an atomic clock is a device t uses ! extremely fa/ vibrations ( molecules or atomic nuclei to measure "t4 ,^! vibrations rema9 con/ant ) "t1 consequ5tly %ort int]vals c be measur$ ) mu* high] precision ?an by me*anical or electrical clocks4 #ac,! #aiff ,nobel ,prize 9 ,physics 0 aw>d$ to ,pr(4 ,alfr$ ,ka/l] ( ! ,univ]sity ( ,p>is = 8 rese>* on optical pump+ & /udies on ! en]gy levels ( atoms4 #ad,see ,accel]ators1 a companion booklet 9 ?is s]ies1 = a full acc\nt ( ! ,/an=d 8,atom ,sma%]04 #ae;,= descriptions ( fission & fusion processes1 see ,controll$ ,nucle> ,fusion1 ,nucle> ,reactors1 & ,nucle> ,p[] ,plants1 o!r booklets 9 ?is s]ies4 #af;,a bit is a digit1 or unit ( in=mation1 9 ! b9>y 7base-(-two7 sy/em us$ 9 electronic data transmission sy/ems4 #ag,see ,,snap1 ,nucle> ,space ,reactors & ,p[] f ,radioisotopes1 o!r booklets 9 ?is s]ies1 = descriptions ( nucle> s\rces ( p[] = space4 ,?is booklet is "o ( ! 8,und]/&+ ! ,atom0 ,s]ies4 ,comm5ts are invit$ on ?is booklet & o!rs 9 ! s]ies2 please s5d !m to ! ,division ( ,te*nical ,in=mation1 ,u4 ,s4 ,atomic ,en]gy ,commission1 ,wa%+ton1 ,d4 ,c4 #bjede4 ,publi%$ z "p ( ! ,,aec's educational assi/ance program1 ! s]ies includes ^! titles3 ,accel]ators ,animals 9 ,atomic ,rese>* ,atomic ,fuel ,atomic ,p[] ,safety ,atoms at ! ,sci5ce ,fair ,atoms 9 ,agriculture ,atoms1 ,nature1 & ,man ,books on ,atomic ,en]gy = ,adults & ,*ildr5 ,c>e]s 9 ,atomic ,en]gy ,comput]s ,controll$ ,nucle> ,fusion ,cryog5ics1 ,! ,uncommon ,cold ,direct ,conv]sion ( ,en]gy ,fall\t ,f ,nucle> ,te/s ,food ,pres]vation by ,irradiation ,g5etic ,effects ( ,radiation ,index to ! ,,uas ,s]ies ,las]s ,micro/ructure ( ,matt] ,neutron ,activation ,analysis ,nonde/ructive ,te/+ ,nucle> ,clocks ,nucle> ,en]gy = ,desalt+ ,nucle> ,p[] & ,m]*ant ,%ipp+ ,nucle> ,p[] ,plants ,nucle> ,propulsion = ,space ,nucle> ,reactors ,nucle> ,t]ms1 ,a ,brief ,gloss>y ,our ,atomic ,_w ,pl[%>e ,plutonium ,p[] f ,radioisotopes ,p[] ,reactors 9 ,small ,packages ,radioactive ,wa/es ,radioisotopes & ,life ,processes ,radioisotopes 9 ,indu/ry ,radioisotopes 9 ,m$ic9e ,r>e ,e>?s ,rese>* ,reactors ,,snap1 ,nucle> ,space ,reactors ,s\rces ( ,nucle> ,fuel ,space ,radiation ,spectroscopy ,syn!tic ,transuranium ,elem5ts ,! ,atom & ! ,ocean ,! ,*emi/ry ( ! ,noble ,gases ,! ,elusive ,neutr9o ,! ,fir/ ,reactor ,! ,natural ,radiation ,environm5t ,:ole ,body ,c\nt]s ,y\r ,body & ,radiation ,a s+le copy ( any "o booklet1 or ( no m ?an ?ree diff]5t booklets1 may be obta9$ free by writ+ to3 ,,usaec1 ,p4 ,o4 ,,box #fb1 ,,oak ,,ridge1 ,,t5nessee #cghcj ,complete sets ( ! s]ies are available to s*ool & public libr>ians1 & to tea*]s :o c make !m available = ref]5ce or = use by gr\ps4 ,reque/s %\ld be made on s*ool or libr>y lett]heads & indicate ! propos$ use4 ,/ud5ts & tea*]s :o ne$ o!r mat]ial on specific aspects ( nucle> sci5ce1 or ref]5ces to o!r read+ mat]ial1 may also write to ! ,oak ,ridge address4 ,reque/s %\ld /ate ! topic ( int]e/ exactly1 & ! use int5d$4 ,9 all reque/s1 include 8,zip ,code0 9 return address4 ,pr9t$ 9 ! ,unit$ ,/ates ( ,am]ica ,,usaec ,division ( ,te*nical ,in=mation ,ext5sion1 ,oak ,ridge1 ,t5nessee ,transcrib]'s ,notes --,sil5tly correct$ a few typos4 --,reta9$ publication in=mation f ! pr9t$ edition3 ?is e,book is public-doma9 9 ! c\ntry ( publication4 --,9 ! text v]sions only1 text 9 italics is delimit$ by und]scores4