TIEU_LUAN_THAY_SON.8268

7/31/2019 TIEU_LUAN_THAY_SON.8268

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Tiu lun v vt l Laser

B GIO DC V O TAOTRNG AI HOC VINH

Tiu lun chuyn ngnh

VT L LASER

ti:

Laser v cc tnh cht ca laser, ng dng

mi nht ca tia laser

Hc vin: H PHI CNG

Lp: CH16 - Quang hc Ngi hng dn :T.S ON HOI SN

Vinh, thng 2 nm 2010

H Phi Cng - Lp CH16 Quang hc 1


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M u

Laser l mt nh sng c bit, hin v ang c nghin cu mtcch c th. Laser l nh sng c bit v n c nhiu tnh cht v cng dnghn hn cc nh sng thng thng khc.

Hin ngi ta da vo cc tnh cht v cng dng ca n ng dngtrong nhiu lnh vc khc nhau.

Vy nhng tnh cht v ng dng nh th no? lm r iu ti chn ti nghin cu: Tnh cht, ng dng v cc ngdng mi nht ca tia laser .



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Chng I. CC TNH CHT CA CHM TIA LASER

Mc du laser c bn cht l sng in t nhng do ngun pht ra laser khchn so vi cc ngun pht nh sng thng thng khc nn n c nhng tnhcht c bit khc vi nh sng thng thng.

1.1 Cng tia laser ln gp bi ln cng tia sng nhit

lm r iu ny ta s so snh cng ca bc x laser vi bc x nhit.Vi laser kh He - Ne c cng sut thp c 1mW ch lin tc

pht ra phton nm trong vng nhn thy c ( 0,6328m), vi nng lngmt phton l h = 10-19J th s phton pht ra trong 1 giy l:

161 10==h

PN (1)

Nhng vi ngun nhit c T c 1000K bc x t din tch A = 1 cm2 vcng pht sng trong vng thy c (6000 0A ) th s phton pht ra trong

mt giy l: 12/2 101

=

kThce

AN (2)

So snh (1) v (2) ta thy cng ca laser kh thng thng gpc 1 vn ln so vi nh sng do bc x nhit.

Vi ngun laser c cng sut ln c 1GW th n gp hng t lnChnh l do nn n tr thnh ngun sng qu gi cho nhng ng

dng c th.

1.2 dnh hng ca Laser cao

Ngun sng nhit bc x theo mi phng trong khng gian. Nhngdo c cu ca bung cng hng ca my pht laser nn n ch pht daong ngang v chng tp trung trong mt mt phng phn cc. Cng sut

pht c phn b u v phn b ng pha trong khu ca ngun.Vi laser sng phng bc x t mt bung cng hng vi gng

ng knh d ( hoc din tch A = d2/4), sau gng chm laser s tn x dohin tng nhiu x, di gc nhiu x = d/, v chm tia bc x trongmt gc khi:

= ()2 = d2/2 = A/2 (3)gi tr gc khi ny nh so vi gc khi bc x ca mt ngun nh sngnhit c 2



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nh hng cao cho s tp trung nng lng trong mt gc khinh v to nn cng ln.1.3 n sc cao

n sc ca mt chm tia c nh ngha l rng vch ph cachm. Khi rng ca vch ph ca chm bng khng th chm c nsc cao nht. C nhiu nguyn nhn dn n bc x c mt rng nhtnh. Trong trng hp gn ng vi bung ccng hng quang hc rng vch c xc nh bng cng thc:

2

14

2

0

=P

hc (4)

Trong :0 : l tm tn s phtP - cng sut pht ca bc xc- thi gian sng ca phton trong bung cng hngh - hng s Planck

Vi laser cng sut pht P = 10-3 W, 1/c ~ 1MHz, vng bc sng c ~ 510-3Hz. y l rng rt b.

Nu s dng khi nim v sch ph:T0 = /0

Ta c: T0 = 17153

10310

510

=

Mun c s n nh tn s trn, bung cng hng phi rt n nh, di ca n phi thay i ( do nhit, nung ) rt t. Ta c th nh gi ihi ny theo t s:


0


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0

=

d

d(6)

t (5) v (6) ta suy ra: d = 10-70

Nh vy cho thy vi cc laser, c c s n nh tn s n sc

cao th bung cng hng phi c b tr khng rung ng v t trongnhng iu kin c bit ( cc gng phn x phi c kp cht nh ccthanh gi bng thp invar t chu thay i v nhit vv...)

1.4 Tnh cht khng gian ca tia laser

1.4.1 S n nh ca cc mode ngangTrong ch dng, ngi ta gi mode ngang l n nh khi s phn

b khng gian ca bin trng ca sng l n nh trong mt phng trc

giao vi trc ca BCH. iu ny c ngha bin v pha ca sng c lpli gi tr ca chnh mnh v khng bin i trong mt tit din ngang caBCH, sau qu trnh sng truyn i v v gia hai gng phn x.

Vi cc BCH c gng cu, sng c dng hnh Gauss do bt kim no trong bung, s phn b cng cng l dng Gauss

)(

2

0

2

2

)( zWr

eIrI

=(7)

Trong : I0 l cng trn trc ca BCH

W(z) bn knh ca vng trn cng gim mt tha se2 s0 vi I0

Khi BCH l n nh th tnh cht khng gian cn biu hin chchm tia laser l ra s gi nguyn tnh cht phn b Gauss khi trong BCHchng l chm phn b Gauss.1.4.2 Tnh chun trc ca chm tia

Trong thc nghim ngi ta b tr cc knh v thu knh s thu ccc chm hu nh song song.1.4.3 S hi t ca chm tia

Vi cc chm sang thng thng, ta khng th hi t chm tia vomt im vi ng knh nh tu do gp hin tng nhiu x.Vi chm tia laser n c th tp trung hi t mt im c din tch

c 2.



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1.5. Tnh cht thi gian ca tia LaserTnh cht ny c th hin trong ch lm vic lin tc hay l xung

ca laser.Hu ht cc laser u c th pht lin tc tr laser Ruby hay laser thu

tinh in him. Ngoi ra, cc laser cng d dng lm vic ch xung nhgnhng bin php k thut ring.

Trong cc tnh cht thi gian ny cn ch my im sau:+ Khi pht lin tc, theo thi gian laser c s thng ging v tn s

nguyn nhn l do c cu ca chnh laser, cc tc ng ngoi cnh vi BCH

+ Khi pht xung nng lng hay cng sut pht lin h vi nhau qua rng xung nh cng thc:

EPc = (9)

y: Pc l cng sut ca nh xung, E l nng lng xung, rng xungNgoi ra, cng sut trung bnh ca xung c xc nh bng cng thc

REPm =vi R l tn s lp li ca xung



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Chng II. CC NG DNG CA TIA LASER

2.1. ng dng ca laser trong nghin cu khoa hc:

a. Nghin cu v Quang hc phi tuyn:

Nh chng ta bit trong quang hc c in cc ngun sng pht sngl nhng ngun khng kt hp v c cng nh. Khi tng tc ca nhsng vi cc mi trng vt cht, phn cc ca mi trng ch l hmtuyn tnh ca cng in trng ca sng ti.

P = E y, P l phn cc ca mi trng.

l cm in ca mi trng.E l cng in trng

Khi cng sng ln nh c bc x laser th ta c th biu din li phn cc nh sau:

P = ...3

3

2

21EEE ++

Khi E cng ln th s hng bc cao ca E cng tr nn c tc dng ln vchng dn n nhng hiu ng mi trc y khng quan st c, lcc hiu ng quang phi tuyn. Ngy nay ngi ta nghin cu k lng ctrn phng din l thuyt ln thc nghim v cc hiu ng quang phi tuyn,m ra mt ngnh khoa hc mi l ngnh Quang hc phi tuyn vi nhiuhng nghin cu khc nhau v ng dng khc nhau lnh vc ny.

b. Holography:

Holography l tn thng gi ca chp nh khi. Nguyn l caholography c xut nm 1948 nhng do ngun sng chp khng mnh nn khng thu c kt qu. Ch t khi c laser, ngi ta s dngngun sng ny thu c nh khi ca vt v nghin cu v holographyc pht trin rt nhanh v tr thnh mt ngnh khoa hc ring trong vt lv quang hc k thut.

+ Holography l mt phng php ghi hnh nh phng php chp nh nhmy nh. Tuy nhin n c nhng u im ni bt hn phng php chpnh thng thng.

- Phng php ny chp nh khng cn thu knh.- N cho hnh nh khi ca vt, ngha l cho hnh nh 3 chiu.- Holography ghi li cc sng tn x t vt bao gm c bin v phaca sng v bt c im no ca Holography cng c cc tn hiu t



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ton vt chp . Do vy, nu nh ta b gy Holography tanh nhiu phnth mi mnh nh cng vn c nhng thng tin ca sng tn x tvt v cho ta hnh nh c vt khi phc hi. y l mt c tnh quantrng ca Holography c th c c nhiu bn sao chp ca vt , d

bo qun v nhn ln.- Do holography c hnh khi nn n c th ghi li tn hiu t cc vt

khc nhau trn cc vng khc nhau, ngha l c th cng mt lc gili nhiu thng tin.

+ Vi nhng u im nh va nu trn th hin ti ngi ta ang v sm ra nhiu ng dng th v v quan trng nh sau:- Nu ngi ta ghi li mt lng thng tin ln mt yu t th tch ca

holography th n c th tr thnh b nh tt nht cho my tnh. V nc ghi li v phc hi bng nh sng nn dn ti vic xy dng ccmy tnh in t quang hc. i vi loi my tnh ny th tc x l

thng tin nhanh gp nhiu ln my tnh hin c do trong my tnhquang hc tc lan truyn tn hiu l vn tc nh sng trong mitrng.

- Khi s dng cc loi nh sng khc nhau ghi li Holoraphy th khiphc hi bng nh sng trng ta c th thy c hnh nh mu cavt. ay chnh l nguyn tc chp nh mu v video mu. V trongtng lai th k thut chp nh, truyn hnh ni v mu rt c trinvng.

- V holography cho ta hnh nh khi vt nn ngi ta c th s dngmu kim tra sn phm nh lp t khi so snh vi mt lp chunxem c sai hng g khng.

- Nh phng php ny ngi ta d dng ghi li hnh nh khi ca ccsinh vt nh khi chng ang chuyn ng hoc ngay c tn la, my

bay khi chng ang chuyn ng c th nghin cu s thay itheo thi gian ca cc vt trn theo nhng mc ch nghin cu khcnhau.

c. Nghin cu plasma nng v cc phn ng nhit hch:

Do tia laser c tnh cht l cng sut cao, ch pht xung c th tc cng sut c 1012 1015 W nn khi bn tia laser vo vt cht c th tora c plasma nhit cao. V nhit cao ny s c cc phn ngnhit hch, t y m ra kh nng nghin cu phn ng nhit hch c iukhin c trong phng th nghim.

d. Nghin cu sinh ha hin i:



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Trong cc phn ng ha hc khi c d tham gia ca nhiu ng v hahc thng gp kh khn khi ta mun loi tr nh hng ca ng v no trong lin kt. Tuy nhin, do cc ng v c nng lng lin kt ha hc saikhc nhau t nn ch c nh tia laser c n sc cao mi d dng ph hylin kt no khi c s tng tc cng hng. Nng lng bc x laser hfs ph hy ch lin kt no tng ng vi nng lng ny m khng nhhng n cc loi dao ng vi tn s f1, f2, f3,khc rt t f. Ngi ta nirng ay chnh l s ph hy hay kch thch chn lc phn ng ha hc.Chnh iu ny m ra kh nng nghin cu cc sn phm trung gian ca hahc, nghin cu qu trnh din bin theo thi gian ca phn ng, y l ium khoa hc m c t by lu nay. Cng chnh nh c laser m cc nhkhoa hc cn c th nghin cu c phn ng trng thi kch thch.

2.2. ng dng ca laser trong khoa hc k thut:

C th ni y l lnh vc rng ri ca s p dng laser v ang c nhiukt qu l th.

a. Trong thng tin lin lc:

V laser c tnh cht l n sc cao v tnh kt hp cao nn laser cs dng rng ri v nhanh nht trong ngnh thng tin lin lc.S dng tia laser c nhng u im sau:So vi sng v tuyn di sng truyn tin ca tia laser ln gp bi v d visng v tuyn tn s s dng l 104 3.1011Hz nn di sng truyn tng lnn 5.104 ln. Do , cc bc x laser nm trong khong 0,4 0,8 m v vimi knh truyn tin l 6,5 MHz th s dng laser ta c th c gn 80.10 5

knh truyn cng mt lc v gp 105 ln knh truyn khi s dng sng ccngn.

Ngoi ra, do tia laser c tnh cht l mang nng lng ln nn n c th ixa hn cc sng v tuyn. Do nu s dng tia laser th gim c hang tln nng lng cn dung. V vy, tia laser c s dng trong truyn tintrong v tr.

V nu s dng cc bc sng thch hp c th truyn tin cc mitrng khc nhau nh trong sng m, di bin

b. Trong nghin cu v tr:

Tia laser c s dng rng ri trong nghin cu v tr, v d nh:- Tia laser c s dng xc nh v tr cc vt th trong v tr.



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- Theo di cc tu v tr v lin lc vi chng.- iu khin cc tu v tr.

2.3. Trong cc ngnh khoa hc khc:

a. Trong cng ngh gia cng kim loi:

Da vo tnh cht tia laser c cng ln nn c th khoan, hn, ct,gt kim loi. Tia laser c ng knh nh nn c th thu c cc l khoanc ng knh c bc sng khoan c nhng kim loi cng nh bchkim, hng ngcVi cc laser xung cng sut ln vic gia cng kim loic tin hnh nhanh v hiu sut cao nn ngy nay n c s dng rng ritrong cc cng on khc nhau.

b. Trong o lng tiu chun:

Tia laser c n nh v tn s tr thnh thc o chiu di chun.Cc bc x ca laser Cd lm tn s chun, bc x ca laser He - Ne otc ca nh sng

c. Trong y hc:

Tia laser cng c s dng rng ri trong lnh vc y hc. Hin nay, CO2c s dng nh con dao m vi cc c im l vt m c hn ngaysau khi m, y l mt vic rt tt cho cc bnh nhn b bnh mu chmng. V vi cc dng c quang hc thch hp vi cc phu thut ni tng.

Vi cc laser pht xung nh ruby ngi ta cng s dng c gicmc, hn gic mc, dn vt bong gic mc cha mt.

Ngoi ra, vi cc laser xung hay laser lin tc cc bc sng khc nhaunh laser bn dn c dng thay cc kim chm cu, l nhng kim khnggy au v cc hu qu khc cho ngi s dng.

d. Trong kh tng:

Dng tia laser c th o c nng cc ht hi nc trong cc mmy d on thi tit. Bng cch th cc bng thm khng trc y,vic xc nh thi tit thng lu v tn km.



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Chng III. CC NG DNG MI NHT CA TIA LASER

Ngy nay, ngi ta ch to ra c gn 500 loi laser khc nhau, ngdng trong rt nhiu lnh vc:

- o c nhng khong cch cc ln, nh trong nghnh thin vn (okhong cach t tri t n cc hnh tinh v khong cch gia cchnh tinh trong v tr).

- Thit lp dn ng nh cc loi bom, tn la c dn ng bnglaser.

- Thng tin lin lc- Cng nghip nng: hn ct kim loi- Cng nghip ch to v kh.- Ci to ging

- Trong y hc (chun on v iu tr bnh, sn sc thm m)

3.1 ng dng ca laser trong y hc:

Khi chiu tia sng laser vo mt h sinh vt nh c th con ngi, s cnhng hiu ng sinh hc xy ra trong c th. Nhng hiu ng sinh hc nyl c s s dng laser trong y hc phc v con ngi.

Khi s dng laser iu tr th yu t quyt nh hiu qu l liu chiu,bao gm cc tham s:

- Cng sut- hi t (mt cng sut )- Thi gian chiu- S ln chiu- Khong cach gia cc ln chiu

Bn cnh c im ca t chc c th ni chiu cng l yu t quantrng gp phn to nn kt qu tt trong iu tr. Cc ng dng c bn ca laser trong y hc:

3.1.1 Trong chun on:

C nhiu thit b chun on s dng laser nh :- My Dopler Laser thm d, o dng mu trong c th.- My chp ct lp laser.- Cc my d tm, o c, dn ng trong chun on.



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3.1.2 Trong iu tr:

ng dng ca laser trong iu tr rt phong ph:

- Da liu : ty xa cc u, mn, cc m sc t nh nt rui tn nhang, cc

bt bm sinh vv- Nhn khoa: rt nhiu ng dng nh iu tr hn gn cc tn thng vngmc, iu tr cc tn thng gic mc, trong cc phu thut sa cha cc ttkhc x ca mt v phu thut iu tr cc bnh l khc ca mt.- H thng tiu ha: Tn si ng mt ch, trong cc th thut ngoi khoaiu tr cc khi u ng tiu ha, trong to hnh thc qun, trong vic hngn cc tn thng mch mu ni tng nh trong cc trng hp ung th,vim lot ng tiu ha, vv..- Sn ph khoa: iu tr cc tn thng bnh l c t cung trnh nguy c

ung th ha.- Tai Mi Hng: iu tr cc tn thng ca dy thanh m, cc bnh lv tn thng vng hng hu.- Thn kinh: iu tr cc tn thng dng u do h thng thn kinh.- H hp: iu tr cc khi u phi, cc tn thng bnh ly khng phi do u,v hn gn c cc tn thng kh qun do t ng ni kh qun khi gy mhay do th thut m kh qun cp cu.- Tim mch: Ph hy cc mng x va thnh ng mch.3.1.3Dao m laser:

Ngi ta s dng cc laser nhit phu thut nh mt dao m bng tiasng laser. in hnh l dao m bng laser CO2. Khi chiu tia laser, t chcc th ni tia i qua s bay hi rt nhanh to nn mt ng ct st nh dao.Do tc dng ca nhit, hai bn ng ct s s hnh thnh ct hng ro sinhhc bo v vt m nn vt m rt v trng v khng b chy mu.V chmtia laser CO2 khng nhn thy nn trong my pht laser phi gn thm laserHe Ne cng sut 1-2 mw pht tia mu dn ng.

* Nhng u im ca dao m laser:

v khun cao v laser to nhit cao ti ng rch v khng c s tipxc gia dng c v c th.Laser CO2 c kh nng va rch ng m va cm mu.To ra hng ro sinh hc bo v chung quanh ng rch.t gy tn thng cho cc t chc ln cn vt m.



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- Thi gian m ngn hn.- Sn sc hu phu thun li hn.- p dng thun li trong nhng trng hp m dao m thng t hiu qu.c bit, dao m laser c s dng phu thut nhng b phn sutrong c th m khng lm tn thng nhng phn c th n i qua. N chtc dng chn lc trn phn m t chc nh sn. Nh l phu thut cc tnthng, cc khi u s no, ty sng, phu thut mt vv.

3.1.4 Tc dng kch thch sinh hc:C rt nhiu loi laser cng sut thp c s dng khai thc kh nngkch thch cc qu trnh sinh hc.

Nhiu cng trnh nghin cu cng nh thc t ng dng lm sng cho thy

hiu ng kch thch sinh hc khi chiu laser c rt nhiu ng dng mang lihiu qu cao trong cng vic phng bnh v cha bnh, duy tr sc khe conngi.* Chiu iu tr vt thng:

+ St trng vt thng+ Tiu hy cc t bo m cht+ Tng cng chng vim, gim au+ Tng sinh cc m lnh+ Kch thch t chc ht vt thng pht trin nhanh+ Thc y nhanh qu trnh lnh so v hi phc chc nng

* Chiu kch thch t chc lnh:

+ hi phc v tng cng sc khe+ duy tr v tng cng hot ng sinh l bnh thng ca cc c quan

trong c th+ iu chnh cc ri lon v tng cng hot ng ca h tim mch+ Duy tr chc nng bnh thng ca cc hot ng tm thn kinh+ Chm cu bng laser

+ Tng lu lng mu n nhng vng c chiu

3.2 ng dng laser to ra v kh ht nhn:

V kh laser khi c bn ra, tuy khng c n nh sng pho thngnhng li pht ra chm tia laser nng lng cao vi tc 300.000 km/giy.

Nng lng ny tp trung rt mnh, khi chiu vo vt th kim loi, trong



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nhy mt s lm cho kim loi nng chy, bc hi, thm ch bin thnh ion.Tc dng gi l hiu ng lan chy nhit. V kh laser ph hoi mc

tiu ch yu nh vo hiu ng . Chm tia laser gy tc dng lan chy cngln hn i vi c th sng, thm ch gy t vong. Cho nn tia laser tngc mnh danh l tia cht chc.

Nu bn a knh hi t ra trc nh nng ly tiu im sng. Tiuim ny c th lm chy giy. Vy m sng ca tia laser cn cao gp vitrm triu, thm ch vi t ln so vi nh nng Mt tri. Nng lng ca nd nhin l rt ln. Do , ngi ta s dng v kh tia laser bn my

bay, tn la ca i phng. Ngoi ra, khi bn vo mc tiu dng kim loi,tia laser cn sinh ra tc dng ph hoi ph. l dng ion hnh thnh dinhit cao ca tia laser khi pht ra khi b mt kim loi, lc phn tc dngs gy ph ti xung kch trn b mt kim loi, lm bin dng, ph hu nhanhchng vt th. ng thi dng ion cn pht ra bc x X, lm cho cc linh

kin in t gn mc tiu b v hiu ho.

Mt iu cn phi ni thm l, chm tia laser cn lm cho ngi ta b mmt hoc tm thi khng nhn thy g. l v mt ngi ging nh mtthu knh hi t, khi b chm laser chiu vo qua hi t ca thu tinh th shnh thnh tiu im trong vng mc, lm cho nng lng laser cng tptrung hn. T chc vng mc cc mng b hp th nng lng ln ca tiuim nh sng, s nhanh chng chuyn thnh nhit nng lm chy bngvng mc, dn n m mt.

3.3 Tia laser phng tu v tr

Khi rung ng, tia laser t nng khng kh cho n khi chy. Mi lnkhng kh chy li to ra mt tia sng lo ln.

thot khi sc ht tri t, lu nay, loi ngi vn s dng tu conthoi, loi tu phi mang theo hng tn nhin liu v hai tn la y ln.

Nhng khng lu na, cc con tu v tr s lt vo khng gian trn mtchm tia laser, cn rt t hoc khng cn cht n y v khng h gy nhim.

tng c bn ng sau k thut y bng nh sng l s dng cc tialaser t mt t t nng khng kh n mc lm khng kh n tung, ycon tu tin ln pha trc. Nu thnh cng, k thut y bng nh sng slm con tu nh hn hng nghn ln, hiu qu hn so vi cc ng c tn las dng cht ho hc v khng gy nhim.

Chng ta s xem xt hai kiu h thng y tin tin: mt kiu c th achng ta t tri t ln mt trng ch trong vng 5 gi ri v kiu kia c th



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a chng ta du lch h mt tri trn cc xa l nh sng.nh sng rc r l khng kh ang chy di vnh tu.Tu v tr nh c y bng laser. Nguyn l rt n gin: con tu s

dng cc tm gng thu nhn v hi t chm laser chiu vo, ri tnng khng kh n khng kh n tung, y con tu i.

Di y l cc thnh phn ca h thng y mang tnh cch mng ny.- Tia laser carbon dioxit: Tia laser xung 10 kW ang c s dng thnghim con tu nh ny l mt trong s nhng tia mnh nht th gii.

- Gng parabole: Phn y ca tu v tr l mt gng hi t chmlaser vo khoang cha khng kh hay cht n y trn tu. Vt truyn thhai, nm trn mt t, l mt gng ging nh knh vin vng c dng hng chm tia laser ln con tu.- Khoang ht thu: Khng kh c hng vo trong khoang ny; ti y

khng kh b t nng ln bi chm laser, gin n ra v y con tu i.- Hydro trn tu: Mt lng nh cht n y hydro c s dng y tnla khi kh quyn qu long khng th cung cp khng kh.

Trc khi bay ln khi mt t, mt lung khng kh nn s y nh contu ln n vn tc khong 10.000 vng/pht. Khi n ang ln xoy vimt tc ti u, tia laser s c bt ln, thi con tu ln khng trung. Tialaser 10 kW ny rung ng mc t 25-28 ln/giy. Bng cch rung ng,n lin tc y con tu ln pha trn. Chm tia sng c hi t bi gng

parabole y ca con tu t nng khng kh ln ti khong t 10.000-30.000 C, nng hn b mt ca mt tri vi ln. Khi khng kh b tnng n nhit cao nh vy, n s bin i sang th plasma (loi kh cs lng cc ht mang in m, dng, tng ng nhau trn mt tri v

phn ln cc v sao) th plasma ny sau n tung y con tu ln phatrn.

Ngoi ra, ngi ta cng s t cc gng bn trong con tu chiu mts chm nng lng v pha trc. Sc nng t chm laser s to ra mtcm kh lm chch hng i ca mt phn lung khng kh i qua con tu,t gip gim bt ma st v gim lng kh nng m con tu hp th.

3.4Thit b iu khin bng laser gip ngi tn tt i li

Cc nh nghin cu thuc i hc Virginia (M) ang th nghim mtmu thit b dnh cho nhng ngi ln tui khng c kh nng i li. Thit

b ny c hnh dng tng t nh xe y tay ca tr con, c cn li v phanhxe bng in c iu khin bng tia laze.



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Thng qua ng c gn km, cc tia laser gip nhn bit quang cnh xungquanh ngi iu khin, d on hng di chuyn ca h kp thi b li

bnh xe trc ng thi kp cht bnh xe sau. Nu pht hin c vt cn, xes t ng b li trnh sang mt bn. Ngi iu khin xe s khng s ngv c phanh xe t ng. Cc nh nghin cu hy vng sp ti h s thit kthm cho xe chc nng nhn bit ging ni con ngi.

3.5Chic ng h chnh xc nht th gii:

S dng cng ngh laser phc tp v mt n nguyn t thu ngn, ccnh khoa hc M to ra chic my o thi gian chnh xc gn nh tuyti, vi sai s 1 giy trong c cuc i ca v tr - khong 15 t nm.

Cc nh khoa hc ti Vin Tiu chun v Cng ngh quc gia Boulder,Colorado, pht trin mt loi ng h nguyn t mi c th tc tc mttriu t ln trong mi giy, chnh xc gp 100-1.000 ln so vi cc ng hvi sng xezi hin nay. Chic ng h ny c gi l ng h nguyn tquang hc, v n p dng cng ngh laser, o nhng khong thi gian ngnnht tng c ghi nhn ti nay. Nguyn l lm vic tng t nh cc loing h nguyn t ra i t thp k 50, nhng thay v vi sng, n s dngnh sng quang hc c tn s cao hn, cung cp thi gian chnh xc hn.

Tng lai, loi ng h ny s ng vai tr quan trng trong nhiu lnhvc cn chnh xc cao nh cc thit b v tinh, Internet, phn phi in,nh bng

3.6My laser ln nht th gii

Trong khong thi gian bng 1/10 t giy, my siu laser Jena s phngra mt ngun nng lng bng tng nng lng ca tt c cc nh my intrn th gii cng li. y s l mt bc tin ln nht trong lch s ngdng laser.

My c xy dng theo m hnh hin i, gm 4.500 it laser mc songsong vi nhau. Trong mi it s c cng sut tng ng vi 100.000ln cng sut ca my qut laser dng trong a CD hin nay.Khi ra mt my laser Jena s c cng sut 1.000 t Watt!

Khi nghin cu sn xut my laser Jena, Sauerbrey cn t c mt ktch khng gian khc. Trong khi cc my phng laser c cng sut ln hin



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nay phi cn mt din tch tng ng vi c mt sn vn ng, th mysiu laser Jena ca ng c t trong mt phng th nghim vn vn c 200m2!

My siu laser Jena s ng gp ln cho vic sn xut ng v phng xdng cho chn on y hc v tr liu bng tia X. Mt khc, vi cng siu mnh, my c th gip kh x cht thi nguy him. Hin nay, cht thiloi ny c x l bng cch bc trong v ch, sau chn su xung lngt hoc th xung y bin.

3.7 Cu ni laser gia cc v tinh

Ln u tin, hai v tinh khong cch trn 30.000 km trao i thngtin c vi nhau thng qua mt chm laser. K thut ny cho php cc v

tinh qu o thp gi thng tin nhanh chng v n nh xung trm x ldi mt t thng qua mt v tinh a tnh qu o cao hn.

Trong th nghim ln ny, cu ni laser (laser link, l mt chm laser cng knh vi mt) c th truyn cc d liu v hnh nh vi tc 5megabits trong mt giy. Hin cc nh khoa hc ang pht trin mt ngtruyn mi c dung lng ln hn nhiu, cho php truyn c m thanh vhnh nh. Cc nh khoa hc s dng h thng laser c tn l SILEX (doC quan V tr chu u ESA v C quan V tr Php CNES trin khai) ni v tinh Artemis vi v tinh thin vn SPOT 4. Chm laser ny c iuchnh tinh vi, cho php SPOT 4 chuyn lng d liu ln vi tc nhanhti Artemis.

Artemis bay qu o a tnh, cch tri t 31.000 km, trong khi SPOT4 di chuyn vi tc 7.000 m/s cao 832 km. Bi vy, cu ni laser

phi c thit lp rt chnh xc. Theo ng Oppenhaeuser, ng truynlaser gn hn, chc chn hn v cn t nng lng hn h thng thu phtsng v tuyn. Vic gi thng tin t cc v tinh quan trc nh SPOT 4 vtri t hin ko di c ting ng h, bi v thng tin phi i qua nhiutrm: Trc ht, v tinh cn lu gi thng tin khi n chuyn ng trn qu

o. Sau , n gi d liu xung mt trm trn mt t. trm ny, thngtin li c sp xp li mt ln na trc khi c gi qua sng radio titrung tm x l.

Nay, s dng cu ni laser, cc nh khoa hc c th rt ngn thi giantruyn tin t cc v tinh qu o thp xung mt t. ng thi, ngtruyn bng laser cng t ra n nh hn rt nhiu.



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3.8Nam chm hot ng bng nh sng:

Chic nam chm do (plastic magnet) nhy cm vi nh sng ny c ths m ra hng ng dng mi cho vic lu gi v c thng tin: B chaquang trng (magneto optic) dng tia laser s c nhng u im nhdung dng ln, r v nhanh

Chic nam chm do, chy bng nh sng (laser) l loi u tin clm t cc phn t hu c (carbon). Tc gi, ng Arthur Epstein, i hcQuc gia Ohio Columbus, v ng Joel Miller thuc H Utah Salt Lake(M), cho rng, c th s dng phng php ha hc vi chnh nhng ctnh ca vt liu. Vic u tin l tng nhit hot ng ca n. Hin nay,vt liu ny ch hot ng nhit cc lnh (-198 C).

Vt liu gm cc nguyn t mangan, an xen vi cc phn t hu c nhxu. Khi n hp th nh sng laser, cc phn t hu c b kch thch, to ramt t trng. Qua , mt h thng quang t (magneto optic) cxc lp, lm nn tng cho cha t tnh. Bnh thng, trong cha in t,chiu ca t trng ph thuc vo dng in, nhng h thng quang t,chiu t trng ph thuc vo nh sng.

Vi cng tng lai, thng tin c th c c, ghi hoc xa nh cctia laser, thng qua hiu ng quang t. Tuy nhin, Epstein tha nhn rngvic s dng hiu ng ny hin cn rt hn ch.

3.9 Dng laser di chuyn xung sng trong kh lnh

Ngi ta c th iu khin ng i ca xung sng cng nh tn s can bng 3 chm laser, gia cc nguyn t kh lnh. K thut nyc ng dng trong vic ch to cc mch quang in v b nhca my tnh lng t.

Ngi ta gn 3 thit b phng laser trong mi trng kh nit cc lnh.My laser th nht (cn gi l my pht tn hiu) phng ra mt xung sng

vo mi trng kh nit. Sau , mt thit b khc, gi l thit b gilaser, phng ra mt tia, hm xung sng li trong kh lnh. Tip theo, mtthit b phng laser th 3 y xung sng ti mt v tr cch v tr ban u 6milimt. Nh vy, xung sng ny c gi v "vn chuyn" gia mitrng ca cc nguyn t kh lnh. Cc nh khoa hc cho bit, trong thnghim ny, h thay i tn s ca xung sng bng cch thay i tn sca thit b gi laser. y l ln u tin ngi ta c th gi mt xung sng,



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iu chnh tn s v di chuyn n gia cc nguyn t kh lnh. V nguyntc, cc nh khoa hc c th m ha thng tin trong xung sng lu gi vs dng. V th, th nghim ln ny l mt bc tin mi trn ng tmkim y l ln u tin ngi ta c th gi mt xung sng, iu chnh tns v di chuyn n gia cc nguyn t kh lnh. V nguyn tc, cc nh khoahc c th m ha thng tin trong xung sng lu gi v s dng. V th,th nghim ln ny l mt bc tin mi trn ng tm kim b nh ltng cho my tnh lng t.

3.10 ng c lng t bin kh thi thnh laser

Lung kh thi nng hi thot ra t ng x khng hn l tha v dng.Ngi ta c th li dng nguyn l c hc lng t chuyn chng thnhnng lng c li di dng bc x laser. Nh vt l Marlan Scully, i

hc Texas A&M (M), thng bo.Scully ni rng, s dng kh thi t ng x ca ng c bn k, ngi

ta cn mt ng c lng t ph (quantum afterburner). ng c ph nyhot ng theo nguyn l c hc lng t, ti s dng nhit lng tha cakh thi chuyn thnh nng lng hu ch di dng bc x laser, nhmnng cao hiu sut ca ton b h thng.

ng c lng t ph ca Scully gm hai thit b: mt to ra laser vmt to ra maser (tia maser l mt loi tia laser vi bc sng siu ngn,

ngn hn bc sng nh sng thng). Bnh thng, trong kh thi nng, slng ht t l nghch vi mc nng lng ca chng. Ngha l, ht c mcnng lng cng cao th mt ca chng cng nh. Tuy nhin, khi i vothit b laser, cc ht trong kh thi b kch thch, lm s lng ht cpnng lng cao tng vt.

ng c lng t s dng cc ht kh thi ba trng thi khc nhau(3 cp nng lng). Thit b maser y cc ht b kch thch cp nnglng th hai ln cp cao nht. Qu trnh ny lm tng mt cc ht nnglng cao gia bc hai v bc mt. Chnh cc ht ny to ra bc x laser.

Tm li, vi vic gn thm mt ng c lng t ph, nhit lng cakh thi c chuyn thnh bc x laser, gp phn nng cao hiu sut caton b h thng. Ngc li, trong mt ng c bn k bnh thng, nhitlng ca kh thi khng dng c na.



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Scully v cng s ang th lp t mt ng c lng t thc s kimnghim tng ny.

3.11 Trng thi th t ca vt cht:

Vt cht, ngoi ba trng thi thng gp l th rn, lng, kh, cn tn ti mt dng c bit khc, c gi l "trng thi plasma", hay l th kh ionho.

Hy ly nc lm v d: un nng mt cc bng n mc nht nh,n ( th rn) s bin thnh nc (th lng), nhit tng ln na nc s

bc hi (th kh). Nu tip tc tng nhit nc ln cao na, kt qu s lg?

Khi nhit cht kh cao hn vi ngn , cc electron mang in m btu bt khi nguyn t v chuyn ng t do, nguyn t tr thnh cc ionmang in dng. Nhit cng cao th s electron bt ra khi nguyn tcht kh cng nhiu, hin tng ny c gi l s ion ho ca cht kh. Ccnh khoa hc gi th kh ion ha l trng thi plasma. Ngoi nhit cao,ngi ta c th dng cc tia t ngoi, tia X, tia bta cc mnh chiu vo chtkh cng lm cho n bin thnh plasma.

Khng phi l xa l

C th bn cm thy trng thi plasma rt him gp. Nhng thc ra lmt trng thi rt ph bin trong v tr. Trong lng phn ln nhng v saopht sng u c nhit v p sut cc cao, vt cht y u trng thiplasma. Ch c mt s hnh tinh ti v vt cht phn tn trong thin hmi c th tm thy cht rn, cht lng v cht kh.

Ngay xung quanh chng ta cng thng gp vt cht trng thi plasma.Nh trong ng n hunh quang, n neon hay trong h quang in sngchi. Hn na, trong tng ion xung quanh tri t, trong hin tng ccquang, trong kh phng in sng chi kh quyn v trong ui ca cc sao

chi u c th thy trng thi k diu ny.

3.12 Lm tia laser ng yn trong tinh th



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