Dab tsi yog qhov ua haujlwm ntawm lub cev dub hauv cov ntsuas kub infrared?
(1) Ib yam khoom uas absorbs xwm txheej tawg ntawm tag nrho cov wavelengths yam tsis muaj kev xav nyob rau hauv tej yam kev mob.(2) Ib yam khoom uas muaj ib tug absorptivity ntawm 1.(3) Ib yam khoom uas absorbs tag nrho cov teeb meem hluav taws xob ntawm tag nrho cov wavelengths ntawm txhua qhov kub thiab txias.
Txhua yam khoom tsis tu ncua radiate, nqus thiab emit electromagnetic tsis. Cov electromagnetic nthwv dej radiated sib txawv ntawm cov wavebands sib txawv thiab nthuav tawm ib qho kev faib spectral. Qhov kev faib tawm no muaj feem xyuam rau ib qho khoom muaj txiaj ntsig thiab qhov kub thiab txias, thiab txhais tau tias yog thermal tawg. Txhawm rau kawm cov cai ntawm thermal tawg tsis muaj kev ywj pheej ntawm cov yam ntxwv ntawm cov khoom siv, physicists tau txhais cov khoom zoo tshaj plaws - lub cev dub, uas yog tus qauv siv rau kev tshawb fawb hluav taws xob thermal. Lub cev dub absorbs tag nrho cov xwm txheej electromagnetic tsis muaj kev xav lossis kev sib kis, thaum tseem emitting hluav taws xob sab nraud.
Raws li Kirchhoff's Law of Radiation, nyob rau hauv ib lub xeev ntawm thermal equilibrium, qhov piv ntawm ib yam khoom lub radiant zog rau nws absorptivity yog ywj siab ntawm nws cov khoom siv thiab nyob ntawm tsuas yog wavelength thiab kub. Raws li txoj cai no, lub cev dub muaj lub zog hluav taws xob muaj zog tshaj plaws ntawm qhov ntsuas kub thiab tseem hu ua lub tshuab hluav taws xob tag nrho.
Hauv infrared thermal imaging, electromagnetic nthwv dej radiated los ntawm cov khoom sib txawv txawv txawv. Lub cev dub ua raws li qhov ntsuas ntsuas, sib npaug rau xoom taw tes. Txij li thaum lub cev dub zoo tshaj plaws tsis muaj nyob hauv qhov tseeb, emissivity yog txhais los ntsuas qhov sib txawv. Rau txhua qhov muab wavelength, emissivity yog hais txog qhov sib piv ntawm lub zog radiant ntawm ib yam khoom tiag tiag nyob rau hauv ib lub voj voog nqaim rau ntawm lub cev dub ntawm tib qhov kub. Emissivity yog ib qho txiaj ntsig zoo ntawm 0 thiab 1, feem ntau cuam tshuam los ntawm cov khoom siv, ib puag ncig thiab kev ntsuas ntsuas. Cov khoom nrog wavelength-yooj yim emissivity yog hu ua grey lub cev, thaum lwm tus yog cais raws li xaiv radiators.
Kev ua haujlwm ntev ntawm infrared thermal imagers muaj kev cuam tshuam rau sab nraud, uas tuaj yeem ua rau kev ntsuas yuam kev. Yog li ntawd, blackbodies yog saws rau ntsuas ntsuas calibration.
