"Invisibility Caps" tseem tsis pom

Qhov tseeb nyob rau hauv ib tug series ntawm "cloaks ntawm invisibility" yog ib tug yug los nyob rau hauv University of Rochester (1), uas siv qhov tsim nyog kho qhov muag system. Txawm li cas los xij, cov neeg tsis ntseeg hu nws qee yam kev dag ntxias lossis cov txiaj ntsig tshwj xeeb, uas lub ntsej muag ntse ntse ua rau pom lub teeb thiab dag ntxias cov neeg saib xyuas lub zeem muag.

Muaj qee qhov kev ua lej zoo nkauj tom qab tag nrho - cov kws tshawb fawb yuav tsum siv nws los nrhiav kev teeb tsa ob lub lo ntsiab muag kom lub teeb pom kev zoo li qhov uas lawv tuaj yeem nkaum qhov khoom ncaj qha tom qab lawv. Qhov kev daws teeb meem no ua haujlwm tsis yog thaum saib ncaj qha ntawm lub lo ntsiab muag - lub kaum sab xis ntawm 15 degrees lossis lwm qhov txaus.

1. "Invisibility Cap" los ntawm University of Rochester.

Nws tuaj yeem siv rau hauv tsheb kom tshem tawm qhov muag tsis pom hauv daim iav lossis hauv chav ua haujlwm, tso cai rau cov kws phais pom los ntawm lawv txhais tes. Qhov no yog lwm qhov nyob rau hauv ib tug ntev series ntawm kev tshwm sim txog invisible technologyuas tau los rau peb xyoo tas los no.

Xyoo 2012, peb twb tau hnov ​​txog "Cap of Invisibility" los ntawm American Duke University. Tsuas yog qhov feem ntau inquisitive nyeem ces nws yog hais txog qhov tsis pom ntawm ib lub tog raj kheej me me nyob rau hauv ib qho me me ntawm lub microwave spectrum. Ib xyoo dhau los, Duke cov tub ceev xwm tau tshaj tawm txog kev siv tshuab sonar stealth uas yuav zoo li pheej hmoo hauv qee lub voj voog.

Hmoov tsis, nws yog pom kev tsuas yog los ntawm qee qhov kev pom thiab hauv qhov nqaim, uas ua rau cov cuab yeej siv me me. Hauv xyoo 2013, cov kws ua haujlwm tsis muaj zog ntawm Duke tau thov cov khoom siv 3D luam tawm uas camouflaged ib yam khoom tso rau hauv nrog micro-qhov hauv cov qauv (2). Txawm li cas los xij, dua, qhov no tau tshwm sim nyob rau hauv ib qho kev txwv ntawm nthwv dej thiab tsuas yog los ntawm qee qhov kev pom.

Cov duab luam tawm hauv Is Taws Nem zoo li kev cog lus Cape Canadian tuam txhab Hyperstealth, uas nyob rau hauv 2012 tau tshaj tawm nyob rau hauv lub npe ntxim nyiam ntawm Quantum Stealth (3). Hmoov tsis zoo, kev ua haujlwm prototypes yeej tsis tau tshwm sim, thiab tsis tau piav qhia nws ua haujlwm li cas. Lub tuam txhab hais txog cov teeb meem kev nyab xeeb raws li qhov laj thawj thiab cryptically qhia tias nws tab tom npaj cov khoom zais zais ntawm cov khoom rau cov tub rog.

Pem hauv ntej saib, rear koob yees duab

Thawj niaj hnubinvisibility cap» Qhia kaum xyoo dhau los los ntawm Japanese engineer Prof. Susumu Tachi los ntawm University of Tokyo. Nws siv lub koob yees duab nyob tom qab ib tug txiv neej hnav lub tsho loj uas tseem yog tus saib xyuas. Daim duab los ntawm lub koob yees duab tom qab tau npaj rau nws. Tus txiv neej cloaked yog "invisible". Ib qho kev ua kom zoo sib xws yog siv los ntawm Adaptiv tsheb camouflage ntaus ntawv qhia nyob rau hauv kaum xyoo dhau los los ntawm BAE Systems (4).

Nws qhia txog cov duab infrared "los ntawm qab" ntawm lub tank lub armor. Xws li lub tshuab tsuas yog tsis pom hauv cov khoom siv pom. Lub tswv yim ntawm kev npog cov khoom coj los ua hauv xyoo 2006. John Pendry ntawm Imperial College London, David Schurig thiab David Smith ntawm Duke University tau luam tawm txoj kev xav ntawm "kev hloov kho qhov muag" hauv phau ntawv Journal Science thiab nthuav tawm nws ua haujlwm li cas hauv microwaves (ntev wavelengths dua li pom lub teeb).

2. Ib qho "invisibility cap" luam tawm hauv peb qhov loj me.

Nrog kev pab los ntawm metamaterials tsim nyog, lub electromagnetic yoj tuaj yeem khoov rau hauv txoj hauv kev los hla cov khoom nyob ib puag ncig thiab rov qab mus rau nws txoj kev tam sim no. Lub parameter characterizing lub dav dav optical cov tshuaj tiv thaiv ntawm nruab nrab yog lub refractive index, uas txiav txim seb yuav ua li cas muaj ntau zaus qeeb dua nyob rau hauv lub nqus tsev vacuum, lub teeb txav nyob rau hauv nruab nrab no. Peb xam nws raws li lub hauv paus ntawm cov khoom ntawm cov txheeb ze hluav taws xob thiab sib nqus permeability.

txheeb ze hluav taws xob permeability; txiav txim siab pes tsawg zaus ntawm kev sib cuam tshuam hluav taws xob hauv ib qho khoom siv tsawg dua li qhov sib cuam tshuam quab yuam hauv lub tshuab nqus tsev. Yog li ntawd, nws yog ib qho kev ntsuas ntawm yuav ua li cas cov nqi hluav taws xob nyob rau hauv ib yam khoom teb rau sab nraud hluav taws xob teb. Cov tshuaj feem ntau muaj qhov zoo permittivity, uas txhais tau hais tias thaj chaw hloov pauv los ntawm cov khoom tseem muaj lub ntsiab lus zoo ib yam li sab nraud.

Tus txheeb ze sib nqus permeability m txiav txim seb qhov sib nqus teb hloov pauv li cas hauv qhov chaw uas muaj cov khoom muab, piv rau cov hlau nplaum uas yuav muaj nyob hauv lub tshuab nqus tsev nrog tib qhov chaw sib nqus sab nraud. Rau tag nrho cov khoom tshwm sim, qhov txheeb ze sib nqus permeability yog qhov zoo. Rau cov ntaub ntawv pob tshab xws li iav lossis dej, tag nrho peb qhov ntau yog qhov zoo.

Tom qab ntawd lub teeb, dhau los ntawm lub tshuab nqus tsev lossis huab cua (cov huab cua tsis txawv me ntsis ntawm lub tshuab nqus tsev) mus rau hauv nruab nrab, yog refracted raws li txoj cai ntawm refraction thiab qhov ratio ntawm lub sine ntawm lub kaum sab xis ntawm qhov tshwm sim mus rau lub sine ntawm lub kaum sab xis ntawm refraction. sib npaug rau qhov refractive index rau qhov nruab nrab no. Tus nqi tsawg dua xoom; thiab m txhais tau hais tias cov electrons nyob rau hauv nruab nrab txav nyob rau hauv lub opposite kev coj mus rau lub zog tsim los ntawm hluav taws xob los yog magnetic teb.

Qhov no yog raws nraim li cas tshwm sim nyob rau hauv cov hlau, nyob rau hauv uas lub dawb electron gas undergoes nws tus kheej oscillations. Yog hais tias qhov zaus ntawm electromagnetic yoj tsis tshaj qhov zaus ntawm cov oscillations ntawm cov hluav taws xob, ces cov oscillations tshuaj ntsuam lub teb hluav taws xob ntawm lub nthwv dej kom zoo uas lawv tsis tso cai rau nws nkag mus tob rau hauv cov hlau thiab txawm tsim ib qho chaw taw qhia oppositely. mus rau sab nraud.

Yog li ntawd, lub permittivity ntawm xws li ib tug khoom yog tsis zoo. Tsis tuaj yeem nkag mus tob rau hauv cov hlau, hluav taws xob hluav taws xob electromagnetic cuam tshuam los ntawm qhov chaw ntawm cov hlau, thiab cov hlau nws tus kheej tau txais cov yam ntxwv luster. Yuav ua li cas yog tias ob hom permittivity tsis zoo? Cov lus nug no tau nug nyob rau hauv 1967 los ntawm Lavxias teb sab physicist Viktor Veselago. Nws hloov tawm hais tias lub refractive index ntawm xws li ib tug nruab nrab yog tsis zoo thiab lub teeb yog refracted nyob rau hauv ib tug txawv kiag li txoj kev tshaj li raws li txoj cai ntawm refraction ib txwm.

5. Negative refraction nyob rau saum npoo ntawm metamaterial - visualization

Tom qab ntawd lub zog ntawm electromagnetic yoj yog xa mus rau pem hauv ntej, tab sis lub maxima ntawm lub electromagnetic yoj tsiv nyob rau hauv opposite kev taw qhia mus rau cov duab ntawm lub impulse thiab lub zog hloov. Cov ntaub ntawv zoo li no tsis muaj nyob hauv qhov xwm txheej (tsis muaj cov tshuaj uas tsis zoo sib nqus permeability). Tsuas yog hauv xyoo 2006 cov ntawv tshaj tawm tau hais los saum toj no thiab hauv ntau lwm cov ntawv tshaj tawm tsim nyob rau xyoo tom ntej, nws muaj peev xwm piav qhia thiab, yog li ntawd, tsim cov qauv tsim nrog qhov tsis zoo refractive index (5).

Lawv hu ua metamaterials. Greek prefix "meta" txhais tau tias "tom qab", uas yog, cov no yog cov qauv tsim los ntawm cov khoom ntuj tsim. Metamaterials tau txais cov khoom uas lawv xav tau los ntawm kev tsim cov hluav taws xob me me uas ua raws li cov khoom sib nqus lossis hluav taws xob ntawm cov khoom. Ntau cov hlau muaj qhov tsis zoo hluav taws xob permeability, yog li nws txaus los tawm hauv chav rau cov ntsiab lus uas muab cov lus teb tsis zoo sib nqus.

Hloov chaw ntawm cov hlau homogeneous, ntau cov hlau nyias nyias nyob rau hauv daim ntawv ntawm daim phiaj cubic yog txuas rau lub phaj ntawm cov khoom siv insulating. Los ntawm kev hloov txoj kab uas hla ntawm cov xov hlau thiab qhov kev ncua deb ntawm lawv, nws muaj peev xwm kho qhov zaus qhov tseem ceeb ntawm cov qauv uas yuav muaj qhov tsis zoo hluav taws xob permeability. Txhawm rau kom tau txais qhov tsis zoo sib nqus permeability hauv qhov yooj yim tshaj plaws, tus qauv tsim muaj ob lub nplhaib tawg ua los ntawm tus neeg xyuas pib zoo (piv txwv li, kub, nyiaj lossis tooj liab) thiab sib cais los ntawm ib txheej ntawm lwm cov khoom.

Xws li ib tug system yog hu ua ib tug split nplhaib resonator - abbreviated li SRR, los ntawm lus Askiv. Split-ring resonator (6). Vim qhov khoob ntawm lub nplhaib thiab qhov kev ncua deb ntawm lawv, nws muaj qee qhov capacitance, zoo li lub capacitor, thiab txij li lub nplhaib yog ua los ntawm cov khoom siv hluav taws xob, nws kuj muaj qee qhov inductance, piv txwv li. muaj peev xwm tsim cov dej ntws.

Cov kev hloov ntawm sab nraud magnetic teb los ntawm electromagnetic yoj ua rau ib tug tam sim no ntws nyob rau hauv lub rings, thiab tam sim no tsim ib tug magnetic teb. Nws hloov tawm hais tias nrog ib tug tsim nyog tsim, lub magnetic teb tsim los ntawm lub system yog qhia opposite rau sab nraud teb. Qhov no ua rau muaj qhov tsis zoo sib nqus permeability ntawm cov khoom uas muaj cov ntsiab lus. Los ntawm kev teeb tsa qhov tsis sib xws ntawm cov txheej txheem metamaterial, ib tus tuaj yeem tau txais cov lus teb tsis zoo sib nqus hauv ntau qhov sib txawv ntawm cov nthwv dej ntau zaus.

meta-tsev

Kev npau suav ntawm cov neeg tsim qauv yog tsim kom muaj ib qho kev ua haujlwm uas cov nthwv dej yuav ua kom zoo nyob ib puag ncig cov khoom (7). Xyoo 2008, cov kws tshawb fawb ntawm University of California, Berkeley, thawj zaug hauv keeb kwm, tau tsim cov ntaub ntawv peb-seem uas muaj qhov tsis zoo refractive index rau pom thiab ze-infrared lub teeb, khoov lub teeb nyob rau hauv ib qho kev taw qhia tawm tsam nws cov kev taw qhia ntuj. Lawv tsim cov khoom siv tshiab los ntawm kev sib txuas cov nyiaj nrog magnesium fluoride.

Tom qab ntawd nws raug txiav mus rau hauv ib lub matrix uas muaj cov koob me me. Qhov tshwm sim ntawm qhov tsis zoo refraction tau pom ntawm wavelengths ntawm 1500 nm (ze infrared). Thaum ntxov 2010, Tolga Ergin ntawm Karlsruhe Institute of Technology thiab cov npoj yaig ntawm Imperial College London tsim pom teeb ntaub. Cov kws tshawb fawb tau siv cov ntaub ntawv muaj nyob hauv khw.

Lawv siv photonic crystals nteg rau ntawm qhov chaw los npog lub microscopic protrusion ntawm lub phaj kub. Yog li cov metamaterial tau tsim los ntawm cov lo ntsiab muag tshwj xeeb. Cov lo ntsiab muag tawm tsam lub hump ntawm lub phaj yog nyob rau hauv xws li ib txoj kev uas, los ntawm deflecting ib feem ntawm lub teeb tsis, lawv tshem tawm cov tawg ntawm lub teeb ntawm lub bulge. Los ntawm kev soj ntsuam lub phaj nyob rau hauv lub tshuab raj, siv lub teeb nrog lub wavelength ze ntawm qhov pom lub teeb, cov kws tshawb fawb pom lub phaj tiaj tus.

Tom qab ntawd, cov kws tshawb fawb los ntawm Duke University thiab Imperial College London tau tswj kom tau txais qhov tsis zoo ntawm microwave hluav taws xob. Yuav kom tau txais cov txiaj ntsig no, tus kheej cov ntsiab lus ntawm cov qauv metamaterial yuav tsum tsawg dua qhov wavelength ntawm lub teeb. Yog li nws yog ib qho kev sib tw uas yuav tsum tau tsim cov qauv metamaterial me me uas phim lub wavelength ntawm lub teeb uas lawv yuav tsum refrac.

Pom pom lub teeb (violet rau liab) muaj lub wavelength ntawm 380 txog 780 nanometers (ib nanometer yog ib billionth ntawm ib 'meter'). Nanotechnologists los ntawm Scottish University of St. Andrews tuaj cawm. Lawv tau txais ib txheej ntawm tsis tshua muaj densely meshed metamaterial. Cov nplooj ntawv ntawm New Journal of Physics piav qhia txog metaflex muaj peev xwm khoov wavelengths txog 620 nanometers (txiv kab ntxwv-liab teeb).

Hauv xyoo 2012, ib pawg neeg tshawb fawb Asmeskas ntawm University of Texas ntawm Austin tuaj nrog kev sib txawv kiag li siv microwaves. Lub tog raj kheej nrog txoj kab uas hla ntawm 18 cm tau coated nrog cov khoom siv tsis zoo ntawm cov ntshav plasma, uas tso cai rau kev tswj hwm cov khoom. Yog hais tias nws muaj raws nraim qhov opposite optical zog ntawm lub zais khoom, nws tsim ib hom ntawm "tsis zoo".

Yog li, ob lub nthwv dej sib tshooj thiab cov khoom ua tsis pom. Raws li qhov tshwm sim, cov khoom siv tuaj yeem khoov ntau qhov sib txawv ntawm cov nthwv dej kom lawv ntws los ntawm cov khoom, sib sau ua ke ntawm lwm sab ntawm nws, uas tej zaum yuav tsis pom zoo rau cov neeg saib xyuas sab nraud. Cov tswv yim theoretical muaj ntau ntau.

Kwv yees li kaum ob lub hlis dhau los, Cov Khoom Siv Kho Kom Zoo Tshaj Plaws tau luam tawm ib tsab xov xwm hais txog qhov kev tshawb fawb los ntawm cov kws tshawb fawb hauv University of Central Florida. Leej twg paub yog tias lawv ua tsis tau raws li cov kev txwv uas twb muaj lawm "cov kaus mom tsis pom» Ua los ntawm metamaterials. Raws li cov ntaub ntawv uas lawv tau luam tawm, qhov ploj ntawm cov khoom hauv qhov pom lub teeb pom kev tuaj yeem ua tau.

7. Txoj kev theoretical ntawm khoov lub teeb ntawm ib qho khoom tsis pom

Debashis Chanda thiab nws pab neeg piav qhia txog kev siv cov metamaterial nrog cov qauv peb sab. Nws muaj peev xwm tau txais nws ua tsaug rau lub npe hu ua. nanotransfer printing (NTP), uas tsim cov hlau-dielectric tapes. Lub refractive index tuaj yeem hloov pauv los ntawm cov txheej txheem nanoengineering. Txoj kev tshaj tawm lub teeb yuav tsum tau tswj hwm hauv peb-dimensional deg qauv ntawm cov khoom siv txoj kev electromagnetic resonance.

Cov kws tshawb fawb tau ceev faj heev hauv lawv cov lus xaus, tab sis los ntawm cov lus piav qhia ntawm lawv cov thev naus laus zis nws tau pom tseeb tias cov txheej txheem ntawm cov khoom siv no muaj peev xwm tiv thaiv cov hluav taws xob hluav taws xob mus rau qhov loj. Tsis tas li ntawd, txoj kev uas cov khoom tshiab tau txais tso cai rau kev tsim cov cheeb tsam loj, uas tau ua rau qee tus npau suav ntawm cov neeg tua hluav taws uas npog hauv cov camouflage uas yuav muab rau lawv. pom kev ua tiav, los ntawm radar mus rau nruab hnub.

Cov khoom siv zais cia siv cov khoom siv los yog cov txheej txheem kho qhov muag tsis ua rau qhov tseeb ploj ntawm cov khoom, tab sis tsuas yog lawv qhov tsis pom kev rau cov cuab yeej tshawb nrhiav, thiab tsis ntev, tej zaum, rau lub qhov muag. Txawm li cas los xij, twb muaj ntau lub tswv yim radical. Jeng Yi Lee thiab Ray-Kuang Lee los ntawm Taiwan National Tsing Hua University tau npaj lub tswv yim theoretical ntawm quantum "cloak of invisibility" muaj peev xwm tshem tawm cov khoom tsis yog los ntawm kev saib, tab sis kuj los ntawm kev muaj tiag tag nrho.

Qhov no yuav ua haujlwm zoo ib yam li qhov tau tham saum toj no, tab sis Schrödinger kab zauv yuav siv los ntawm Maxwell qhov sib npaug. Lub ntsiab lus yog txhawm rau ncab qhov khoom qhov tshwm sim teb kom nws sib npaug rau xoom. Raws li txoj cai, qhov no ua tau ntawm microscale. Txawm li cas los xij, nws yuav siv sij hawm ntev los tos cov txheej txheem kev tsim khoom xws li npog. Zoo li ib qho "invisibility cap"Qhov twg tuaj yeem hais tau tias nws tau zais qee yam los ntawm peb qhov kev xav.