ne rg y, ne rg y e mpe ra ture Infra re d E he rma l E a nd T - PDF document

ne rg y, ne rg y e mpe ra ture Infra re d E he rma l E a nd T T

ne rg y he rma l E T

e mpe ra ture – Absolute Ze ro ne rg y a nd he rma l E T T

E le c troma g ne tic Spe c trum Visible X- Ultra T.V. Radio Infrared Microwaves Rays Violet 0.1µ 1 µ 10 µ 100 µ 0.1cm 1cm 10cm 1m 10m 100m 1km 0.1 � 1 � 10 � 100 � Middle Extreme Visible Far Infrared Near Infrared Infrared Infrared VB GY OR 3µ 4µ .4µ .6µ .8µ 1.5µ 2µ 6µ 8µ 10µ 15µ 20µ 30µ

Prope rtie s of Infra re d E ne rg y • All obje c ts e mit infra re d e ne rg y • Infra re d E ne rg y E xhibits the Sa me Prope rtie s a s Visible L ig ht – T ra ve ls in stra ig ht line s a t the spe e d of lig ht – Bounc e s off re fle c tive surfa c e s – T ra nsmits throug h IR windows

T he Re la tionship of E ne rg y to T e mpe ra ture • E mitte d infra re d e ne rg y is proportiona l to the obje c t’s te mpe ra ture – As obje c ts g e t hotte r, the y e mit more e ne rg y – As obje c ts g e t c oole r, the y e mit le ss e ne rg y • T he a mount of e ne rg y e mitte d is a func tion of te mpe ra ture & e missivity • Opa que obje c ts e mit e ne rg y a t a ll wa ve le ng ths – E ne rg y is visible to the e ye a t te mpe ra ture s a bove a bout 1200°F (650°C)

missions Bla c kbody E

ne rg y vs Wa ve le ng th Infra re d E

a w qua tion Ste fa n- Boltzma n L Pla nk’s E

Infra re d E ne rg y vs. T e mpe ra ture Calibration Curve PRO 42 Auto Null Sensor Measured Temperature (°C) -17 8 33 58 83 108 133 158 183 208 233 258 283 308 333 358 383 408 433 458 483 508 533 0.14 0.12 En erg y (W atts/cm ^2) 0.10 0.08 0.06 0.04 0.02 0.00 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1,00 0 Measured Temperature (°F) 2um Sensor

ra nsmission Re fle c tivity missivity, a nd E T

De finition of a Bla c kbody 1. A bla c kbody a bsorbs a ll inc ide nt ra dia tion 2. F or a g ive n te mpe ra ture a nd wa ve le ng th, no surfa c e c a n e mit more e ne rg y tha n a bla c kbody 3. All bla c kbody ra dia tion is inde pe nde nt of dire c tion

Sc ie ntific De finition of E missivity missivity ( ε ) is: E T he ra tio of infra re d e ne rg y e mitte d by a n obje c t c ompa re d to the a mount of infra re d e ne rg y e mitte d by a pe rfe c t e mitte r (bla c kbody) a t the sa me te mpe ra ture . ε = (Me a sure d IR E ne rg y)/ (Bla c kbody Va lue )

De finition of E missivity E missivity is: T he a bility of a n obje c t to e mit infra re d e ne rg y is e qua l to the a bility of a n obje c t to a bsorb infra re d e ne rg y. E missivity = Absorption. E missivity = 100% - Re fle c tivity - T ra nsmission

E ne rg y T ra nsmission, Absorption, & Re fle c tion Incident Energy Incident Energy is either absorbed, reflected, or E transmitted E A E = E + E + E T A R ER E Absorbed T Energy Reflective Energy Energy Transmitted Emissivity = E / E A

Simple De finition of E missivity E missivity is: F or a n opa que ma te ria l, e missivity is the opposite of re fle c tivity. E = 100% - Re fle c tivity.

Surfa c e E missivity Cha ra c te ristic s • E missivity is: – A prope rty of the ta rg e t ma te ria l & surfa c e – Be twe e n 0.000 a nd 1.000 (1 = pe rfe c t e mitte r) – Inde pe nde nt of c olor • F or some ma te ria ls, e missivity is re la tive ly hig h & c onsta nt. • F or some ma te ria ls e missivity is le ss tha n 1 a nd va ria ble due to c ha ng e s in ma te ria l, surfa c e oxida tion, surfa c e roug hne ss, mic rostruc ture or c oa ting .

Surfa c e E missivity Cha ra c te ristic s E missivity Va rie s With Cha ng e s in … • Ma te ria l or Alloy, • Surfa c e Oxida tion, • Surfa c e Roug hne ss, • Mic rostruc ture , or • Surfa c e Conta mina tion. • Dire c tion (a ng le ) • Wa ve le ng th

E missivity of Se le c t Ma te ria ls* • Me ta llic s a nd the ir Oxide s – Polishe d Aluminum .04 – Anodize d Aluminum .82 – Polishe d Sta inle ss Ste e l .23 – L ig htly Oxidize d SS .33 – Hig hly Oxidize d SS .67 • Non Me ta llic s – Conc re te .88- .93 – Pa int, white zinc oxide .92 – Alumina Bric k .40 – Ka olin Bric k .70 – Wa te r .92 * Incropera, F.P. and DeWitt, D.P. Fundamentals of Heat and Mass Transfer, 3 rd Edition, pp. A27-A29

Wa ve le ng th Issue s

Atmosphe ric Absorption

E missivity of Cold Rolle d Ste e l Normal Spectral Emissivity of Cold Rolled Steel 0.55 0.5 0.45 Touloukian and DeWit t 0.4 Iuchi Emissivity Gaskey Eqn. 0.35 Met allic Theory (Fe @800 C) 0.3 0.25 0.2 0.15 0.1 0 1 2 3 4 5 6 Wavelength (microns)

E rror due to E missivity Va ria tion – Brig htne ss Se nsor

De finition of e - slope F or a dua l- wa ve le ng th pyrome te r ope ra ting a t wa ve le ng ths λ 1 a nd λ 2

missivity Va ria tion – Ra tio Se nsor rror due to E E

Gre y vs. Non- Gre y Surfa c e • Gre y Surfa c e - E missivity is inde pe nde nt of wa ve le ng th – Most c e ra mic s a nd othe r non- me ta llic s • Non- Gre y Surfa c e - e missivity de pe nds on wa ve le ng th – Most me ta llic s, inc luding ste e l

T ra nsmission Cha ra c te ristic s (Se le c tive E mitte rs) Glass Quartz Transmission % Transmission % 0 5 10 0 5 10 Wavelength μ m Wavelength μ m Polyester Polyethylene Transmission % Transmission % 0 5 10 0 5 10 Wavelength μ m Wavelength μ m

T e mpe ra ture Applic a tion Issue s BACKGROUND HEATED TARGET REFLECTIONS FOV Target Area w/ Diameter (d) HEAT Field of View SOURCE (FOV) Intervening Media Working FOV Full FOV Distance (D) Target Partially Area Filled FOV SENSOR Δ T (System) = Δ T (Emissivity) + Δ T (Transmission) + Δ T (Background) + Δ T (Instrument) + Δ T (Alignment )

Brig htne ss Se nsors • T e nd to me a sure a n a ve ra g e te mpe ra ture va lue • Are a ffe c te d by c ha ng e s in e missivity, optic a l obstruc tion & stra y ba c kg round e ne rg y • Wa ve le ng th Ma tte rs!

Ra tio Se nsors • Compe nsa te for e missivity va ria tion, a nd te nd to me a sure the hotte st te mpe ra ture vie we d. • Are a ffe c te d by c ha ng e s in e - slope , wa ve le ng th- se le c tive optic a l obstruc tion a nd e xc e ssive ly hot ba c kg round re fle c tions. • Wa ve le ng th Ma tte rs!

Multi- Va ria nt Se nsors • Are use d whe ne ve r tra ditiona l se nsors a re not a ppropria te . • Use multiple wa ve le ng ths to c ha ra c te rize the e missive na ture of the me a sure me nt. • Multi- Va ria nt a lg orithms a re de ve lope d for e a c h a pplic a tion type (usua lly the sa me from one pla nt to the ne xt) to a ddre ss spe c ific e missivity or inte rfe re nc e issue s.

Multi- Wa ve le ng th Infra re d T he rmome te rs • De sig ne d for diffic ult ma te ria ls a nd c ha lle ng ing a pplic a tions. • Use d whe re sing le - & dua l- wa ve le ng th se nsors c a n’t me e t re quire me nts • Common me a sure me nts inc lude Aluminum, Bra ss, Coppe r, Zinc , Ga lva nne a l, Sta inle ss Ste e l, E le c tric a l Ste e l, Hig h Stre ng th Ste e l, Cold Rolle d Ste e l, Ma g ne sium, Chrome , e tc … .

Adva nc e d Infra re d T e c hnolog ie s Brig htne ss T e c hnolog y • Auto Null T e c hnolog y for L ow- T e mpe ra ture , Short- Wa ve le ng th, – Sing le - Wa ve le ng th Me a sure me nts. L ow or Va rying E missivity a t L ow T e mpe ra ture s (be low 400- 600 F / – 200- 300 C) L ow T e mpe ra ture Me a sure me nt throug h Windows. – Na rrow ba nd wa ve le ng ths to a void c ommon inte rfe re nc e sourc e s or – to me a sure se le c tive e mitte rs. Dua l- Wa ve le ng th T e c hnolog y • Compe nsa te s for va rying e missivity, optic a l obstruc tions, – te mpe ra ture g ra die nts, a nd misa lig nme nt. Unique wa ve le ng th se le c tion to vie w throug h wa te r a nd ste a m a nd – for low- te mpe ra ture me a sure me nt. Adva nc e d Sig na l Conditioning with Unique E SP T e c hnolog y – Multi- Wa ve le ng th T e c hnolog y • Use d for Non- Gre ybody Me a sure me nts. – Adva nc e d Sig na l Conditioning with Unique E SP T e c hnolog y –

Othe r Infra re d T e c hnolog ie s • L ine Sc a nne rs • T he rma l Ima g ing Ca me ra s • F la me De te c tors • Hot Me ta l De te c tors • T wo- Compone nt Ba c kg round Compe nsa tion Syste m • L a se r Re fle c tion Multi- Va ria nt T ype