Txhua yam khoom siv kho qhov muag, tsis hais txog lawv qhov tshwj xeeb thiab lub hom phiaj, yuav tsum muaj ib tus yam ntxwv ntawm lub cev, uas yog hu ua "kev daws teeb meem". Cov cuab yeej ntawm lub cev no yog qhov txiav txim siab rau txhua yam khoom siv kho qhov muag thiab ntsuas qhov muag yam tsis muaj kev zam. Piv txwv li, rau lub tshuab kuaj kab mob, qhov tseem ceeb tshaj plaws tsis yog tsuas yog lub zog loj ntawm nws cov lo ntsiab muag, tab sis kuj yog qhov kev daws teeb meem, uas qhov zoo ntawm cov duab ntawm cov khoom hauv kev kawm ncaj qha nyob ntawm. Yog tias tus qauv tsim ntawm cov cuab yeej no tsis muaj peev xwm muab cais qhov kev nkag siab ntawm cov ntsiab lus me tshaj plaws, tom qab ntawd cov duab tshwm sim yuav tsis zoo txawm tias muaj qhov nce ntxiv.
Qhov kev daws teeb meem ntawm cov cuab yeej kho qhov muag yog tus nqi uas ua rau lawv muaj peev xwm paub qhov txawv ntawm tus kheej cov ntsiab lus tsawg tshaj plawspom lossis ntsuas cov khoom. Qhov kev daws teeb meem yog qhov tsawg kawg nkaus nyob nruab nrab ntawm qhov chaw nyob ib sab (cov ntsiab lus) ntawm ib qho khoom, uas lawv cov duab tsis pom tias yog cov khoom sib cais ntawm cov khoom, sib koom ua ke. Qhov kev ncua deb me me, qhov kev daws teeb meem ntawm lub cuab yeej siab dua.
Kev sib cuam tshuam ntawm kev daws teeb meem yog kev ntsuas kev daws teeb meem. Qhov kev ntsuas tseem ceeb tshaj plaws no txiav txim siab qhov zoo ntawm cov cuab yeej thiab, raws li, nws tus nqi. Vim yog cov khoom sib txawv ntawm lub teeb nthwv dej, tag nrho cov duab ntawm cov khoom me me ntawm ib qho khoom zoo li cov chaw ci ntsa iab uas nyob ib puag ncig los ntawm cov txheej txheem ntawm cov voj voog sib cuam tshuam. Nws yog qhov tshwm sim uas txwv qhov kev daws teeb meem ntawm ib qho khoom siv kho qhov muag.
Raws li txoj kev xav ntawm lub xyoo pua 19th English physicist Rayleigh, cov duab ntawm ob lub ntsiab lus me me ntawm ib qho khoom tseem tuaj yeem paub qhov txawv yog tias lawv qhov sib txawv siab tshaj plaws coincides. Tab sis txawm tias qhov kev daws teeb meem no muaj nws qhov txwv. Nws yog txiav txim los ntawm qhov kev ncua deb ntawm cov ntsiab lus me tshaj plaws ntawm cov khoom. Qhov kev daws teeb meem ntawm lub lens feem ntau yog txiav txim siab los ntawm qhov siab tshaj plaws ntawm cov kab pom cais ib millimeter ntawm daim duab. Qhov tseeb no tau tsim los ua pov thawj.
Kev daws teeb meem ntawm cov cuab yeej txo qis hauv qhov muaj qhov tsis sib xws (kev sib txawv ntawm lub teeb ntawm lub teeb los ntawm kev qhia) thiab ntau yam yuam kev hauv kev tsim cov tshuab kho qhov muag, uas ua rau kom qhov ntev ntawm qhov chaw diffraction. Yog liYog li, qhov me me ntawm qhov diffraction me ntsis, qhov siab dua qhov kev daws teeb meem ntawm ib qho optics. Nov yog qhov taw qhia tseem ceeb.
Qhov kev daws teeb meem ntawm ib qho khoom siv kho qhov muag yog ntsuas los ntawm nws cov khoom siv kho vajtse, cuam tshuam txhua yam uas cuam tshuam rau qhov zoo ntawm cov duab muab los ntawm cov cuab yeej no. Xws li cov cuam tshuam, ntawm chav kawm, yuav tsum ua ntej ntawm tag nrho cov muaj xws li aberration thiab diffraction - lub rounding ntawm obstacles los ntawm lub teeb nthwv dej thiab, yog li ntawd, lawv deviation los ntawm ib tug rectilinear kev taw qhia. Txhawm rau txiav txim siab txog kev daws teeb meem ntawm ntau yam khoom siv kho qhov muag, tshwj xeeb pob tshab lossis opaque kuaj daim hlau nrog tus qauv qauv, hu ua worlds, yog siv.
