25.08.19Thaum nws los txog rau kev ntes cov duab meej thiab txhim khu kev qha hauv kev tshawb fawb tshawb fawb, qhov zoo ntawm koj cov ntaub ntawv nyob ntawm ntau dua li qhov kev daws teeb meem lossis qhov loj me. Ib qho tseem ceeb tshaj plaws - tab sis qee zaum saib tsis tau - kev ntsuas yog Qhov Ntsuas-rau-Noise Ratio (SNR). Hauv cov duab kos duab, SNR txiav txim siab seb koj tuaj yeem paub qhov txawv ntawm qhov teeb meem tiag tiag (cov ntaub ntawv muaj txiaj ntsig) los ntawm lub suab tsis xav tau.
Hauv daim ntawv thov kev tshawb fawb xws li microscopy, astronomy, thiab spectroscopy, SNR tsis zoo tuaj yeem txhais tau tias qhov sib txawv ntawm kev kuaj pom lub hom phiaj faint thiab ploj nws tag nrho. Kab lus no tshawb xyuas seb SNR txhais li cas, vim li cas nws tseem ceeb, nws cuam tshuam qhov sib txawv, thiab yuav ua li cas xaiv thiab ua kom zoo dua lub koob yees duab tshawb fawb raws li qhov ntsuas qhov tseem ceeb no.
Qhov Ntsuas-rau-Noise Ratio yog dab tsi thiab Nws txhais li cas?
Lub Teeb Pom Kev rau Noise Ratio (SNR) yog qhov kev ntsuas tseem ceeb tshaj plaws ntawm peb cov duab zoo, qhov tseem ceeb ntawm cov duab sib piv, thiab feem ntau yog qhov tseem ceeb tshaj plaws los txiav txim siab seb lub koob yees duab puas txaus rau koj daim ntawv thov.
Kev sim los txhim kho lub koob yees duab rhiab heev tig ib ncig ntawm ob qho tib si txhim kho cov teeb liab sau:
● Los ntawm kev txhim kho hauv quantum efficiency lossis nce pixel loj
● Txo lub koob yees duab nyob ntawm lub suab nrov
Lub suab nrov ntxiv ua ke, tab sis nyob ntawm qhov xwm txheej ib tus tuaj yeem ua tus thawj coj, thiab yuav tsum tau tsom mus rau thaum sim txhim kho SNR - los ntawm kev ua kom zoo dua los yog teeb tsa, lossis hloov kho kom zoo dua qhov chaw teeb pom kev zoo, optics, thiab koob yees duab.
Nws yog ib qho luv luv los piav txog cov duab nyob rau hauv cov nqe lus ntawm ib qho teeb liab-rau-suab nrov piv, piv txwv li thov ib daim duab muaj SNR ntawm '15'. Txawm li cas los xij, raws li pom tseeb los ntawm lub npe, lub teeb liab-rau-lub suab sib piv nyob ntawm lub teeb liab, uas yuav yog qhov txawv rau txhua pixel. Qhov no yog qhov muab peb cov duab.
SNR ntawm ib daim duab feem ntau yog hais txog SNR ntawm lub ncov teeb liab ntawm kev txaus siab hauv daim duab. Piv txwv li, SNR los ntawm cov duab ntawm cov fluorescent hlwb nyob rau hauv ib tug tsaus nti tom qab yuav siv lub ncov teeb liab siv los ntawm cov pixels ntawm ib tug qauv ntawm kev txaus siab nyob rau hauv lub cell.
Nws tsis yog tus sawv cev coj, piv txwv li, tus nqi nruab nrab rau SNR ntawm tag nrho cov duab. Nyob rau hauv cov tswv yim xws li fluorescence microscopy qhov twg ib tug tsaus nti keeb kwm yav dhau nrog xoom pom photons tuaj yeem tshwm sim, cov xoom teeb liab pixels muaj SNR ntawm xoom. Yog li ntawd, qhov nruab nrab ntawm ib daim duab yuav nyob ntawm seb muaj pes tsawg tus pixels tom qab tau pom.
Yog vim li cas SNR tseem ceeb rau Scientific Cameras
Hauv kev tshawb fawb imaging, SNR cuam tshuam ncaj qha tias koj tuaj yeem txheeb xyuas cov ntsiab lus tsis zoo, ntsuas cov ntaub ntawv kom muaj nuj nqis, thiab rov tsim cov txiaj ntsig.
●Duab Clarity- Siab dua SNR txo cov graininess thiab ua kom pom cov qauv zoo.
●Cov ntaub ntawv raug- Txo qhov ntsuas qhov ua yuam kev hauv kev sim siv zog.
●Low-light Performance- Qhov tseem ceeb rau fluorescence microscopy, sib sib zog nqus-ntev astrophotography, thiab spectroscopy, qhov twg photon suav tsis tshua muaj.
Seb koj siv asCMOS koob yees duabrau cov duab nrawm lossis CCD txias rau cov ntawv thov raug pom ntev, kev nkag siab SNR pab koj sib npaug ntawm kev ua lag luam tawm.
Yuav ua li cas SNR Influences Image Contrast
Qhov sib txawv yog qhov sib txawv ntawm qhov sib txawv ntawm qhov chaw teeb thiab qhov tsaus ntuj ntawm daim duab. Rau ntau daim ntawv thov, cov duab zoo sib xws hauv thaj chaw txaus siab yog lub hom phiaj kawg.
Muaj ntau yam nyob rau hauv cov kev kawm imaging, optical system thiab imaging tej yam kev mob uas yog lub hauv paus txiav txim yam tseem ceeb ntawm cov duab sib piv, xws li lens zoo thiab npaum li cas ntawm lub teeb tom qab.
●Siab SNR→ Kev sib cais ntawm qhov kaj thiab tsaus ntuj; npoo tshwm nkig; subtle cov ntsiab lus tseem pom.
●Tsawg SNR→ Tsaus thaj chaw tau ci dua vim lub suab nrov, thaj chaw ci ntsa iab tau dimmer, thiab tag nrho cov duab zoo sib xws flattens.
Piv txwv li, hauv fluorescence microscopy, tsawg SNR tuaj yeem ua rau cov qauv tsis muaj zog fluorescent sib xyaw rau hauv keeb kwm yav dhau, ua rau kev soj ntsuam ntau yam tsis ntseeg. Hauv astronomy, cov hnub qub faint lossis galaxies tuaj yeem ploj tag nrho hauv cov ntaub ntawv nrov.
Txawm li cas los xij, tseem muaj qhov tseem ceeb hauv lub koob yees duab nws tus kheej - qhov tseem ceeb tshaj plaws yog Lub Teeb Pom Kev rau Noise Ratio. Tsis tas li ntawd, thiab tshwj xeeb tshaj yog thaum lub teeb qis, cov duab siv scaling, yuav ua li cas cov duab tso tawm ntawm lub monitor, plays lub luag haujlwm loj hauv kev pom cov duab sib piv. Nrog lub suab nrov nyob rau hauv qhov tsaus ntuj ntawm daim duab, nws pib duab scaling algorithms tuaj yeem muaj lawv cov kev khi qis qis dhau los ntawm cov nqi qis tsis zoo, thaum lub siab ua ke yog nce los ntawm cov suab nrov hauv cov teeb liab siab pixels. Qhov no yog qhov ua rau tus yam ntxwv 'ntxuav-tawm' grey tsos ntawm cov duab qis-SNR. Qhov zoo sib xws tuaj yeem tau txais los ntawm kev teeb tsa qis dua rau lub koob yees duab offset.
Tej yam uas cuam tshuam rau SNR hauv Scientific Cameras
Ntau qhov kev tsim thiab kev ua haujlwm tsis zoo cuam tshuam rau SNR ntawm lub koob yees duab system:
Technology ntawm Sensor
● sCMOS – Muab cov suab nrov nyeem qis thiab cov ncej siab, zoo tagnrho rau kev ua duab zoo.
● CCD - Keeb kwm muaj suab nrov nyob rau hauv qhov ntev, tab sis qeeb dua li niaj hnub CMOS tsim.
● EMCCD - Siv cov khoom siv hluav taws xob los txhawb cov cim tsis muaj zog, tab sis tuaj yeem ua kom paub ntau lub suab nrov.
Pixel Loj thiab Fill Factor
Loj pixels sau ntau photons, ua rau lub teeb liab thiab yog li SNR.
Quantum Efficiency (QE)
QE siab dua txhais tau tias ntau cov photons tau hloov mus rau electrons, txhim kho SNR.
Lub sij hawm nphav raug
Kev nthuav tawm ntev dua tuaj yeem sib sau ntau cov photons, ua kom lub teeb liab, tab sis kuj tseem tuaj yeem ua rau muaj suab nrov tam sim no.
Txias Systems
Txias txo qhov tam sim no tsaus nti, txhim kho SNR kom ntev ntev.
Optics thiab Illumination
Cov lo ntsiab muag zoo thiab lub teeb pom kev ruaj khov ua kom lub teeb liab ntes thiab txo qhov sib txawv.
Piv txwv ntawm Txawv Peak SNR tus nqi
Hauv kev kos duab, PSNR feem ntau yog hais txog qhov kev xav siab tshaj plaws ntawm pixel saturation. Txawm hais tias muaj qhov sib txawv ntawm cov duab kos duab, cov duab kos duab thiab cov cuab yeej siv lub koob yees duab, rau cov koob yees duab scientific, cov duab nrog tib lub teeb liab-rau-lub suab sib piv tuaj yeem muaj qhov sib xws. Qib ntawm 'graininess', variation ntawm ncej mus rau ncej, thiab rau qee qhov sib txawv, txhua tus tuaj yeem zoo sib xws nyob rau hauv cov xwm txheej sib txawv. Yog li ntawd, nws muaj peev xwm nkag siab txog SNR qhov tseem ceeb thiab cov xwm txheej sib txawv thiab cov teeb meem uas lawv cuam tshuam los ntawm cov duab sawv cev, xws li cov uas pom hauv lub rooj.
Nco tseg: Peak teeb liab qhov tseem ceeb hauv photoelectrons rau txhua kab yog muab xiav. Tag nrho cov duab tso tawm nrog nws pib histogram scaling, ignoring (saturating) 0.35% ntawm lub brightest thiab darkest pixels. Sab laug ob kab duab: Lens-raws li kev yees duab ntawm lub hom phiaj kev sim duab. Txoj cai plaub kab: Ascaris ntes nyob rau hauv fluorescence nrog lub hom phiaj 10x microscope. Txhawm rau qhia txog qhov sib txawv ntawm cov ncej-rau-thav duab hauv cov txiaj ntsig pixel ntawm qis SNR, peb qhov txuas ntxiv tau muab.
Lub lens-raws li duab ntawm lub hom phiaj kev sim, nrog rau cov duab fluorescence microscopy yog ob qho tib si pom, nrog rau kev pom zoo ntawm cov duab fluorescent uas qhia qhov sib txawv hauv 3 qhov txuas ntxiv. Lub ncov yees duab-electron suav ntawm txhua theem teeb liab kuj tau muab.
Daim duab hauv qab no qhia tag nrho cov qauv ntawm cov duab piv txwv no rau kev siv.
Cov duab puv loj siv rau cov teeb liab-rau-nruab nrab piv piv cov lus
Sab laug: Ib qho kev sim ntsuas lub hom phiaj thaij duab nrog lub lens.
Txoj cai: Ib qho piv txwv ntawm Ascaris nematode worm seem saib nrog fluorescence microscopy ntawm 10x magnification.
SNR hauv Applications
SNR yog lub luag haujlwm tseem ceeb hauv ntau qhov chaw:
● Microscopy - Kev kuaj pom faint fluorescence hauv cov qauv tshuaj lom neeg yuav tsum muaj SNR siab kom tsis txhob muaj qhov tsis zoo.
● Astronomy – Txheeb xyuas cov galaxies nyob deb lossis exoplanets xav tau ntev ntev nrog lub suab nrov tsawg.
● Spectroscopy - High SNR ua kom qhov tseeb qhov kev ntsuas siab tshaj plaws hauv kev tshuaj xyuas tshuaj.
● Kev Tshawb Fawb Kev Lag Luam - Hauv cov kab sib dhos uas tsis muaj teeb pom kev zoo, SNR siab pab tshawb xyuas qhov tsis xws luag.
Xaiv lub koob yees duab kev tshawb fawb nrog txoj cai SNR
Thaum ntsuas lub koob yees duab scientific tshiab:
●Tshawb xyuas SNR Specifications- Sib piv dB qhov tseem ceeb nyob rau hauv cov xwm txheej zoo ib yam li koj daim ntawv thov.
●Ntsuas Lwm Cov Kev Ntsuas- Xav txog quantum efficiency, dynamic ntau yam, thiab ncej tus nqi.
●Match Technology siv Case- Rau kev kub ceev dynamic scenes, lub koob yees duab sCMOS tej zaum yuav zoo tagnrho; rau cov kev kawm ultra-low-light static, ib qho txias CCD lossis EMCCD yuav ua tau zoo dua.
●Kev sib txuas rau Workflow Efficiency- Thaum tsis cuam tshuam rau SNR ncaj qha, cov yam ntxwv xws li HDMI tso zis tuaj yeem ua kom pom cov duab hauv lub sijhawm, pab koj tshawb xyuas sai sai tias koj qhov kev yuav khoom tau ua tiav qhov xav tau SNR.
Xaus
Teeb liab-rau-Noise Ratio (SNR) yog qhov kev ntsuas tseem ceeb uas cuam tshuam ncaj qha rau qhov pom tseeb thiab kev ntseeg siab ntawm cov duab tshawb fawb. Nkag siab seb SNR txhais li cas, cov yam ntxwv uas cuam tshuam rau nws, thiab qhov cuam tshuam ntawm qhov sib txawv SNR qhov tseem ceeb tso cai rau cov kws tshawb fawb thiab cov neeg siv khoom los ntsuas cov duab kos duab zoo dua. Los ntawm kev siv qhov kev paub no-txawm yog xaiv ib qho tshiablub koob yees duab scientificlos yog optimizing ib qho kev teeb tsa uas twb muaj lawm - koj tuaj yeem xyuas kom meej tias koj cov duab ua haujlwm tau txais cov ntaub ntawv nrog rau qib ntawm qhov xav tau rau koj daim ntawv thov tshwj xeeb.
FAQs
Dab tsi yog qhov "zoo" SNR rau cov koob yees duab tshawb fawb?
Qhov zoo tshaj SNR nyob ntawm daim ntawv thov. Rau kev xav tau ntau, kev ua haujlwm ntau - xws li fluorescence microscopy lossis astronomy - ib qho SNR saum 40 dB feem ntau pom zoo, vim nws tsim cov duab nrog cov suab nrov tsawg thiab khaws cov ntsiab lus zoo. Rau kev siv dav dav hauv chav kuaj lossis kev tshuaj xyuas kev lag luam, 35-40 dB tuaj yeem txaus. Txhua yam hauv qab no 30 dB feem ntau yuav pom pom cov nplej thiab tuaj yeem cuam tshuam qhov tseeb, tshwj xeeb tshaj yog nyob rau hauv qhov tsis sib xws.
quantum efficiency (QE) cuam tshuam SNR li cas?
Quantum efficiency ntsuas qhov zoo npaum li cas lub sensor hloov cov photons tuaj rau hauv electrons. QE siab dua txhais tau tias ntau dua ntawm cov teeb pom kev zoo yog ntes tau raws li cov teeb liab, txhawb nqa tus lej hauv qhov sib npaug SNR. Qhov no yog qhov tseem ceeb tshwj xeeb tshaj yog nyob rau hauv cov teeb meem tsis tshua muaj teeb meem, qhov twg txhua photon suav. Piv txwv li, sCMOS lub koob yees duab nrog QE ntawm 80% yuav ua tiav SNR siab dua nyob rau hauv cov xwm txheej zoo ib yam piv rau lub sensor nrog 50% QE, tsuas yog vim nws ntes cov teeb liab siv tau ntau dua.
Dab tsi yog qhov txawv ntawm SNR thiab Contrast-to-Noise Ratio (CNR)?
Thaum SNR ntsuas tag nrho cov teeb liab lub zog txheeb ze rau lub suab nrov, CNR tsom rau qhov pom ntawm qhov tshwj xeeb tiv thaiv nws keeb kwm yav dhau. Hauv kev tshawb fawb pom, ob qho tib si tseem ceeb: SNR qhia koj li cas "huv" daim duab tag nrho, thaum CNR txiav txim siab seb cov khoom tshwj xeeb ntawm kev txaus siab sawv tawm txaus rau kev kuaj xyuas lossis ntsuas.
Xav kawm ntxiv? Ua tib zoo saib cov lus hais txog:
Quantum Efficiency nyob rau hauv Scientific Cameras: A Beginner's Guide
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