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

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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

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SLIDE 1

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

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SLIDE 2

T he rma l E ne rg y

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SLIDE 3

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

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SLIDE 4

E le c troma g ne tic Spe c trum

X- Rays Ultra Violet Visible Infrared Microwaves T.V. Radio Visible

VB GY OR

Near Infrared Middle Infrared Far Infrared Extreme Infrared

0.1 1 10 100 0.1µ 1 µ 10 µ 100 µ 0.1cm 1cm 10cm 1m 10m 100m 1km .4µ .6µ .8µ 1.5µ 2µ 3µ 4µ 6µ 8µ 10µ 15µ 20µ 30µ

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SLIDE 5

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

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SLIDE 6

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

  • bje 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)

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SLIDE 7

Bla c kbody E missions

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SLIDE 8

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

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SLIDE 9

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

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SLIDE 10

Infra re d E ne rg y vs. T e mpe ra ture

Calibration Curve

PRO 42 Auto Null Sensor

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1,00 Measured Temperature (°F) En erg y (W atts/cm ^2)

  • 17

8 33 58 83 108 133 158 183 208 233 258 283 308 333 358 383 408 433 458 483 508 533 Measured Temperature (°C)

2um Sensor

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SLIDE 11

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

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SLIDE 12

De finition of a Bla c kbody

1. A bla c kbody a bsorbs a ll inc ide nt ra dia tion 2. F

  • r 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

  • f dire c tion
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SLIDE 13

Sc ie ntific De finition of E missivity

E missivity (ε) is:

T he ra tio of infra re d e ne rg y e mitte d by a n

  • bje 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 )

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SLIDE 14

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

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SLIDE 15

E ne rg y T ra nsmission, Absorption, & Re fle c tion

Incident Energy is either absorbed, reflected, or transmitted

Reflective Energy E Incident Energy ER Absorbed Energy E A E T

E = E + E + E R T A

Energy Transmitted

Emissivity = E / E

A

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SLIDE 16

Simple De finition of E missivity

E missivity is:

F

  • r a n opa que ma te ria l, e missivity is the
  • pposite of re fle c tivity.

E = 100% - Re fle c tivity.

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SLIDE 17

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
  • r some ma te ria ls, e missivity is re la tive ly

hig h & c onsta nt.

  • F
  • r 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 .

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SLIDE 18

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
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SLIDE 19

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, 3rd Edition, pp. A27-A29

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SLIDE 20

Wa ve le ng th Issue s

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SLIDE 21

Atmosphe ric Absorption

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SLIDE 22

Normal Spectral Emissivity of Cold Rolled Steel 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 1 2 3 4 5 6 Wavelength (microns) Emissivity

Touloukian and DeWit t Iuchi Gaskey Eqn. Met allic Theory (Fe @800 C)

E missivity of Cold Rolle d Ste e l

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SLIDE 23

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

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SLIDE 24

De finition of e - slope

F

  • r a dua l- wa ve le ng th pyrome te r ope ra ting

a t wa ve le ng ths λ1 a nd λ2

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SLIDE 25

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

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SLIDE 26

Gre y vs. Non- Gre y Surfa c e

  • Gre y Surfa c e - E

missivity is inde pe nde nt

  • f 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
  • n wa ve le ng th

– Most me ta llic s, inc luding ste e l

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SLIDE 27

T ra nsmission Cha ra c te ristic s (Se le c tive E mitte rs)

Wavelength μm Wavelength μm Wavelength μm Wavelength μm Glass Quartz Polyester Polyethylene

0 5 10 0 5 10 0 5 10 0 5 10

Transmission % Transmission % Transmission % Transmission %

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SLIDE 28

T e mpe ra ture Applic a tion Issue s

FOV Target Area Full FOV Partially Filled FOV FOV Target Area w/ Diameter (d) HEATED TARGET BACKGROUND REFLECTIONS Working Distance (D) HEAT SOURCE Intervening Media Field of View (FOV) SENSOR ΔT (System) = ΔT (Emissivity) + ΔT (Transmission) + ΔT (Background) + ΔT (Instrument) + ΔT (Alignment)

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SLIDE 29

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!
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SLIDE 30
  • 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

  • bstruc 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!

Ra tio Se nsors

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SLIDE 31

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.

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SLIDE 32
  • 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 … .

Multi- Wa ve le ng th Infra re d T he rmome te rs

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SLIDE 33
  • Brig htne ss T

e c hnolog y

–

Auto Null T e c hnolog y for L

  • w- T

e mpe ra ture , Short- Wa ve le ng th, Sing le - Wa ve le ng th Me a sure me nts.

–

L

  • w or Va rying E

missivity a t L

  • w T

e mpe ra ture s (be low 400- 600 F / 200- 300 C)

–

L

  • w 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

Adva nc e d Infra re d T e c hnolog ie s

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SLIDE 34
  • 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

Othe r Infra re d T e c hnolog ie s