Basics of Noncatact Temperature Measurement - Infrared

8/14/2019 Basics of Noncatact Temperature Measurement - Infrared

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nfrared:non-contact IRemperature sensors

and handheldndustrial IR sensors, thermometers andandhelds for non-contact

measurement, monitoring andnspection, also with lasersight

Non-contact infrared sensors, IR sensors and IR measuring devices for non-contactnd wear-free temperature measurement and monitoring, also with laser crosshairs,or portable and inline and online measurement, also as portable handhelds for hermography, thermal imagers, IR imagers


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Optris

Physical Basics

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With our eyes we see the world in visible light. Whereas visiblelight fills only a small part of theradiation spectrum, theinvisiblelight coversmost of the remainingspectralrange. The radiationof invisible lightcarries much more additionalinformation.

Each body with a temperature above the absolute zero(-273.15C = 0 Kelvin) emits an electromagnetic radiationfrom its surface, which is proportional to its intrinsic temperatu-re.A part of this so-calledintrinsic radiationis infrared radiation,which canbe used to measure a bodystemperature. Thisradi-ation penetrates the atmosphere. With the help of a lens (inputoptics) thebeamsare focusedon a detector element, which ge-

nerates an electrical signal proportional to the radiation. Thesignal is amplified and, using successive digital signal proces-sing, is transformed into an output signal proportional to theobject temperature. The measuring value may be shown in adisplay or released as analog output signal, which supports aneasy connection to control systems of the process manage-ment.

The Infrared Temperature Measurement System

The advantages of non-contact temperaturemeasurement are clear - it supports:

- temperature measurements of moving or overheatedobjects and of objects in hazardous surroundings

- very fast response and exposure times- measurement without inter-reaction, no influence on the

measuring object

- non-destructive measurement- long lasting measurement, no mechanical wear

The Electromagnetic Radiation Spectrum

A spectrum in the physical sense is the intensity of a mixture ofelectromagnetic waves as the function of the wavelength or fre-quency. The electromagnetic radiationspectrum coversa wave-length area of about 23 decimal powers and varies from sectorto sector in origin, creation and application of the radiation. Alltypes of electromagnetic radiation follow similar principles ofdiffraction, refraction, reflection and polarisation. Their expan-sion speed corresponds to the light speed under normal con-ditions: The result of multiplying wavelength with frequency isconstant:

f = c

The infrared radiation coversa very limited part in thewhole ran-ge of the electromagnetic spectrum: It startsat the visiblerangeof about 0.78 m and ends at wavelengths of approximately1000m.

Discovery of the Infrared Radiation

Searching for new optical material William Herschel by chancefound the infrared radiation in 1800.He blackened the peakof asensitive mercury thermometer. This thermometer, a glassprism that led sun rays onto a table made his measuring arran-gement. With this, he testedthe heating of different colorsof thespectrum.Slowly movingthe peak of theblackenedthermome-ter through the colors of the spectrum, he noticed the increa-sing temperature fromvioletto red. The temperature rose evenmore in the area behind the red end of the spectrum. Finally hefound the maximum temperature far behind the red area.Nowadays thisarea is calledinfraredwavelengtharea.

Infrared SystemObject Optics Sensor Electronics Display

William Herschel (1738 - 1822)

The electromagnetic spectrum with the infrared area used by pyrometers.


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3

Drawing of a black body:1 ceramic conduit, 2 heating, 3 conduit made from Al O 4 aperture 2 3 ,

Wavelengths ranging from 0.7 to 14 m are important for infra-red temperature measurement. Above these wavelengths theenergylevel is so low, that detectorsare notsensitive enoughtodetectthem.

In about 1900 Planck, Stefan, Boltzmann, Wien and Kirchhoffprecisely defined the electromagnetic spectrum and estab-lished qualitative and quantitative correlations for describingthe infrared energy.

A black body isa radiator, which absorbs allincoming radiation.It showsneither reflection nor transmissivity.

1 ( Absorption, Emissivity)

A black body radiates the maximum energy possible at each

wavelength. The concentration of the radiation does not de-pend on angles. The black body is the basis for understandingthe physical fundamentsof non-contact temperature measure-mentandfor calibratingthe infrared thermometers.

Physical Basics

The Black Body

= =

The construction of a black body is simple. A thermal hollowbodyhasa small holeat one end.If the bodyis heatedandrea-ches a certain temperature, inside the hollow room a balancedtemperature spreads. The hole emits ideal black radiation ofthis temperature. For each temperature range and application

purpose theconstruction of these black bodiesdependson ma-terial and the geometric structure. If the hole is very small com-pared to thesurface asa whole,the interference of theidealsta-te is very small. If you point the measuring device on this hole,you can declare the temperature emitting from inside as blackradiationwhich youcan usefor calibrating your measuringdevi-ce. In reality simple arrangements use surfaces, which are co-vered with pigmented paint and show absorption and emissivi-ty values of 99% within the required wavelength range. Usuallythis is sufficient for calibrations of realmeasurements.

The radiation lawby Planck shows thebasic correlation for non-contact temperature measurements: It describes the spectralspecific radiation M of the black body into the half space de-pending on itstemperatureT andthe wavelength.

Radiation Principles of a Black Body

s

With rising temperatures the maximum of the spectral specificradiationshifts to shorter wavelengths.As theformula isvery ab-stract it cannot be used for many practical applications. But,you may derive various correlations from it. By integrating thespectral radiation intensity for all wavelengths from 0 to infinite

you can obtainthe emitted radiation value of the bodyas a who-le. Thiscorrelation is calledStefan-Boltzmann-Law.

The entire emitted radiation of a black body within the overallwavelength range increases proportional to the fourth power ofits absolute temperature. The graphic illustration of Planckslaw also shows, that the wavelength, which is used to generatethe maximum of the emitted radiation of a black body, shiftswhen temperatures change. Wiens displacement law can bederived from Plancks formula by differentiation.

The wavelength, showing the maximum of radiation, shifts withincreasing temperature towards the range of short wave-lengths.

M T [Watt m] = 5.67 10 W M K

T = 2898 m K

s= 4 -8 -2 -4

max

C = light speedC = 3.74 10 W mC = 1.44 10h = Planck's constant

1

2

-16

-2 K m

The following illustration shows the graphic description of theformula dependingon with differenttemperaturesas parame-ters.

Spectral specific radiation M of theblack bodydepending on thewavelength s

Visible spectrum Wavelength in m

10 4

100

10 -2

10 -4

10 -6

10 -1 10 0 10 1 10 2 10 3

W

cm 2 m

6000 K

3000 K

800 K

300 K

77 K

1 1=M = s2 hc

5 e hc/ kT - 1 e 1C2 / T -

c1

5


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Thermopile TS80

The illustration shows the general construction of an infrared

thermometer. Withthe help of input optics theemitted object ra-diation is focused onto an infrared detector. The detector ge-nerates a corresponding electrical signal which then is ampli-fied and may be used for further processing. Digital signal pro-cessing transforms the signal into an output value proportionalto the object temperature. The temperature result is eithershown on a display or may be used as analog signal for furtherprocessing. In order to compensate influences from the sur-roundings a second detector catches the temperature of themeasuring device and of his optical channel, respectively.Consequently, the temperature of the measuringobjectis main-ly generatedin three steps:

1. Transformation of the received infrared radiation into an elec-trical signal

2. Compensation of background radiation from thermometerand object

3. Linearization and output of temperature information.

Besides the displayed temperature value, the thermometersal-so support linear outputs such as 0/4-20 mA, 0-10 V and ther-mocouple elements, which allow an easy connection to controlsystems of theprocess management. Furthermore, the most ofthe presently used infrared thermometers offer digital inter-faces (USB, RS232, RS485) for further digital signalprocessingand in order to be able to have access to the device parame-ters.

The most importantelement in each infrared thermometer is theradiation receiver, alsocalleddetector.

There are2 main groupsof infrared detectors.

Infrared Detectors

Infrared Detectors

Thermal DetectorsThermopile detectorPyroelectrical detectorBolometer FPA (for IR cameras)

Quantum Detectors

Thermal Detectors

In these detectors the temperature of the sensitive elementvarys because of the absorption of electromagnetic radiation.This leads to a modified property of the detector, which

depends on temperature. This change of the property will beelectrically analysed and used as a standard for the absorbedenergy.

If the joint between two wires of different metallic material heatsup, the thermoelectrical effect results in an electrical voltage.The contact temperature measurement has been using thiseffect for a long time with the help of thermocouple elements. Ifthe connection is warm because of absorbed radiation, thiscomponent is called radiation thermocouple. The illustrationshows thermocouples made of bismuth/antimony which are

arranged on a chip round an absorbing element. In case thetemperature of the detector increases, this results in a propor-tionalvoltage,which canbe caughtat theend of thebond isles.

Radiation Thermocouple Elements (Thermopiles)

Optris

Physical Basics

4

Construction and Operation of Infrared Thermometers

Block diagram of an infrared thermometer

IR-Detector

Pre-amplifier ADC Processor

Digital Interface

DAC 4 - 20 mA

The Grey Body

Only few bodies meet the ideal of the black body. Many bodiesemit far less radiation at thesame temperature. The emissivitydefines the relation of the radiation value in real and of the blackbody. It is between zero and one. The infrared sensor receivesthe emitted radiation from the object surface, but also reflectedradiation from the surroundings and perhaps penetrated infra-red radiation from the measuringobject:

emissivityreflection

transmissivity

Most bodies do not show transmissivity in infrared, thereforethe following applies:

This fact is very helpful as it is much easier to measure thereflection thanto measure the emissivity.

= 1

+

+ +

= 1


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U - C T + C T + C Tamb amb pyrn n n

C T =obj

n

The illustration shows the common construction of a pyroelec-tric detector. This sensitive element consists of pyroelectric ma-terial with two electrodes. The absorbed infrared radiationresults in a changed temperature of thesensitive element whichleads to a changed surface loading due to the pyroelectric

effect. The so created electric output signal is processed by apreamplifier. Due to the nature of how the loading is generatedin the pyroelectric element the radiation flow has to be con-tinuously and alternately interrupted. The advantage of the fre-quenceselectivepreamplifying is a bettersignal to noise ratio.

Bolometers use the temperature dependency of the electric re-sistance. The sensitive element consists of a resistor, whichchanges when it absorbs heat. The change in resistance leadsto a changed signal voltage. The material should have a high

temperature factor of the electrical resistance in order to workwith highsensitivity andhigh specific detectivity.

Bolometers which work at room temperature use the tempera-ture coefficient of metallic resistors (e.g. black layer and thinlayer bolometer) as well as of semiconductor resistors (e.g.thermistor bolometers). Nowadays infrared imagers are basedon the following technological developments:

The semiconductor technology replaces mechanical scan-ners. FPAs (Focal Plane Arrays) are produced on the basis ofthin layer bolometers. For that purpose VOX (Vanadium oxide)or amorphous silicon are used as alternative technologies.These technologies significantly improve the price-performance ratio. The latest standard include 160 x 120 and

320 x 240 elementarrays.

The decisive difference between quantum detectors and ther-maldetectorsis their fasterreaction on absorbed radiation. Themode of operation of quantum detectors is based on the photoeffect.The striking photons of theinfraredradiation lead to an in-crease of theelectrons into a higherenergy level insidethe semi-conductormaterial. When theelectronsfall back an electric sig-nal (voltage or power). Also a change of the electric resistanceis possible. These signals can be analysed in an exact way.

Quantum detectorsare very fast (nsto s).The temperature of the sensitive element of a thermal detectorchanges relatively slowly. Time constants of thermal detectorsare usually bigger than time constants of quantum detectors.

Bolometers

Quantum Detectors

Roughly approximated one can say that time constants ofthermal detectors can be measured in Milliseconds whereastime constants of quantum detectors can be measured inNanoseconds or even Microseconds. Despite of the fast de-velopmenton thefieldof quantum detectorsthereare lots of ap-plications, where thermal detectorsare preferably used. That iswhythey areequally positioned with thequantum detectors.

As per the Stefan-Boltzmann law the electric signal of the de-tectoris as follows:

U ~ T

As the reflected ambient radiation and the self radiation of theinfrared thermometer is to be considered as well, the formula isas follows:

U detector signalT object temperatureT temperature of background radiationT temperature of the deviceC device specific constant.

= 1- reflection of the object

As infrared thermometers do not cover the wavelength rangeas a whole, the exponent n depends on the wavelength . Atwavelengths ranging from 1 to 14 m n is between 17 and 2 (atlong wavelengths between 2 and 3 and at short wavelengthsbetween15 and17).

U = C ( T + (1- ) T - T )

Thus theobjecttemperature is determined as follows:

Transformation of Infrared Radiation into an ElectricalSignal and Calculation of the Object Temperature

obj

obj

amb

pyr

obj amb Pyr

4

n n n

U = C ( T + (1 )T - obj amb4 4- T )Pyr4

The results of these calculations for all temperatures are storedas curve band in the EEPROM of the infrared thermometer.Thus a quick access to the data as well as a fast calculation ofthe temperature are guaranteed.

The formula show that theemissivity is of centralsignificance,if you want to determine the temperature with radiation measure-ment. The emissivity stands for the relation of thermal radia-tions, which are generated by a grey and a black body at thesame temperature. The maximum emissivity for the black bodyis 1. A grey body is an object, which has the same emissivity atallwavelengthsand emits less infrared radiationthan a black ra-diator ( < 1). Bodies with emissivities, which depend on thetemperature as well as on the wavelength, are called non greyor selective bodies(e.g. metals).

Emissivity

Pyroelectric Detektors

Construction of a pyroelectric detector

Pyroelectricmaterial Radiation flow

Preamplifier

Backelectrode Frontelectrode(low in reflection)

5


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Spectral permeability of plastics made from polethylene.

The emissivity depends on the material, its surface, temperatu-re, wavelengthand sometimes on the measuring arrangement.Many objects consisting of nonmetallic material show a highand relatively constant emissivity independent from theirsurface consistency, at leastin longwave ranges.

Generallymetallic materials show a lowemissivity, which stronglydepends on the surface consistency and which drop in higherwavelengths.

Temperature Measurement of Metallic MaterialsThis may result in varying measuring results. Consequently, al-ready the choice of the infrared thermometer depends on thewavelength and temperature range, in which metallic materials

show a relatively high emissivity. For metallic materialsthe shor-test possible wavelength should be used, as the measuringerror increases in correlation to the wavelength.

The optimal wavelength for metals ranges with 0.8 to 1.0m forhigh temperatures at the limit of the visible area. Additionally,

wavelengths of1.6 m,2.2m and 3.9m are possible.

Transmissivitiesof plastics vary with the wavelength. They reactinversely proportional to the thickness, whereas thin materialsare more transmissive than thick plastics. Optimal measure-ments canbe carriedout with wavelengths,where transmissivi-ty is almost zero independent fromthe thickness. Polyethylene,polypropylen, nylon and polystyrene are non-transmissive at3.43 m, polyester, polyurethane, teflon, FEP and polyamideare non-transmissive at 7.9 m. For thicker and pigmentedfilms wavelengths between 8 and 14 m will do. The manufac-turer of infrared thermometerscan determine the optimal spec-tral range for thetemperature measurement by testing theplas-tics material. The reflection is between 5 and 10 % for almost allplastics.

Temperature Measurement of Plastics

Optris

Emissivity and Temperature Measurement

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Measurement error of 10 % as result of wrongly adjusted emissivity and in de- pendenceon wavelengthand object temperature.

object temperature (C)

M e a s u r e m e n t

e r r o r

i n % 10

8 -14 m

30002500150010000

2

4

6

8

2000

3.9 m

10

30002500150010005000

2

4

6

8

2000

2.2 m

1.0 m

5.0 m

500

Wavelength in m

Spectral emissivity of some materials1 Enamel, 2 Plaster, 3 Concrete, 4 Chamotte

Wavelength in m

Spectral emissivity of metallic materials1 Silver, 2 Gold, 3 Platin, 4 Rhodium, 5 Chrome, 6 Tantalum, 7 Molybdenum

Wavelength in m

T r a n s m i s s i v i t y

i n %


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Temperature Measurement of Glass

If you measure temperatures of glass it implies that you takecare of reflection and transmissivity. A careful selection of thewavelength facilitates measurements of the glass surface aswell as of thedeeperlayers of theglass. Wavelengthsof 1.0 m,2.2 m or 3.9 m are appropriate for measuring deeper layerswhereas 5 m are recommended for surface measurements. If

temperatures are low, you should use wavelengths between 8and 14 m in combination with an emissivity of 0.85 in order tocompensate reflection. For this purpose a thermometer withshort response time should be used asglass is a bad heat con-ductor and can change its surface temperaturequickly.

Additional influences can arise from heat sources in the en-vironment of the measuring object. To prevent wrong measu-ring results due to increased ambient temperatures, the infra-red thermometer compensates the influence of ambient tem-peratures beforehand (as e.g. when measuring temperaturesof metals in industrial ovens, where the oven walls are hotterthan the measuring object). A second temperature sensing he-ad helps to generate accurate measuring results by automati-cally compensating the ambient temperatures and a correctlyadjusted emissivity.

Dust, smoke andsuspended matterin theatmosphere canpol-lute theoptics andresult in false measuringdata. Here airpurgecollars (which are installed in front of the optics with compres-sed air) help to prevent deposition of suspended matter in frontof the optics. Accessories for air andwater cooling support theuse of infrared thermometers even in hazardoussurroundings.

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Spectral transmissivity of glassWavelength in m

100

80

60

40

20

0 2 3 4 5


i n %

Spectral transmissivity of air (1 m, 32C, 75 % r. F.)Wavelength in m


i n %

2 4 6 8 10 12 14 16

100

75

50

25

0

Influence from the Surroundings

The illustration shows that the transmissivity of air stronglydepends on the wavelength. Strong flattening alternates withareas of high transmissivity - the so-called atmosphericwindows. The transmissivity in the longwave atmosphericwindow (8 - 14 m) is constantly high whereas there aremeasurable alleviations by the atmosphere in the shortwavearea, which may lead to false results. Typical measuringwindowsare1.11.7m,22.5mand35m.

Compensating ambient influences

Ambient radiation

Infrared thermometer

Atmospheric Absorption

Measuring object

Spectral transmissivity of plastic layers made of polyester

Wavelength in m


i n %

20

102030405060708090

100

3 4 5 6 7 8 9 10 11 1 2 13 14

0,25 mm Dicke


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Optical Diagram of an Infrared Sensor

Transmissivity of typical infrared materials (1 mm thick)1 Glass, 2 Germanium, 3 Amorphous Silicon, 4 KRS5

Experimental Determination of Emissivities

Construction of the Infrared Thermometers

Optics and Window

In the addendum you will find emissivity dates for variousmaterials from technical literature and measurement results.Thereare differentwaysto determine the emissivity.

Method1: With thehelp of a thermocouple

Method 2: Creating a black body with a test object from the measuring material.

Method3: With a referenceemissivity

With the help of a contact probe (thermocouple) an additionalsimultaneous measurement shows the real temperature of anobject surface. Now the emissivity on the infrared thermometerwill be adapted so that the temperature displayed correspondsto the value shown with the contact measurement. The contactprobe should have good temperature contact and only a low

heat dissipation.

A drilled hole (drilling depth


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Thetableshowsvarious windowmaterials in a survey.

Windows with anti reflection coating have a significantly highertransmissivity (up to 95%). The transmissivity loss can be cor-rected with the transmissivity setup, in case the manufacturerspecified the corresponding wavelength area. If not, it hasto beidentifiedwith an infrared thermometer anda reference source.

New principles of measurement and sighting techniques facili-tate an improved and precise use of infrared thermometers.Developments field of solid state lasers are adapted for multip-le laser arrangements to mark the spot sizes. Thus, the realspot sizes inside the objectfield are denoted with the help of la-ser crosshairs techniques. Different products use video came-ra chips instead of optical sighting systems.

Simple, cost-effective portable infrared thermometers use sing-le point laser aimersin order to distinguish thecentre of thespotwith a parallax default. With that technique the user has to esti-matethe spotsize withthe helpof the spotsizediagramandthelikewise estimated measuring distance. If the measuring objecttakes only a part of the measuring spot, temperature rises areonly displayed as average value of hot area and ambient coldarea. A higher resistance of an electric connection due to a cor-roded contact results in an undulyheating.Due to small objectsand inappropriate big spotsizes,thisrisewillbe shownas a mi-nor heating, only: Thus, potentially dangerous heatings maynot be recognized in time. In order to display spots in their realsize, optical sighting systems with a size marking were deve-loped. They allow an exact targeting. As laser pyrometers aresignificantly easier and safer than contact thermometers, engi-neers have tried to mark the spot size with laser sighting techni-ques independently from the distance - according to the dis-

Latest Trends in Sighting Techniques

Development of High-Performance Optics combined withLaser Crosshairs Techniques

tance-spot-size-ratioin the diagram.

Two warped laser beams approximately show the narrowing ofthe measuring beam and its broadening in longer distances.The diameter of the spot size is indicated by two spots on theouter circumference. Due to the design the angle position ofthese laser points on the circuit alternates which makes an ai-mingdifficult.

New laser sighting techniques support to denote measuringspots of infrared thermometers as real-size crosshairs, exactlymatching the measuringspotin theirdimension.

The Principle of the Crosshairs

Four laser diodesare arranged in symmetricalorder aroundtheinfrared optical measuring channel. They are connected to linegenerators, which create a line of defined length inside thefocus distance. The line generators, arranged in pairs, faceeach other. They overlap the projected laser lines at the focus.That way crosshairs are generated, which exactly display thediameter of the measuring spot. At longer or shorter distancesthe overlapping is only partly. Thus the user has a changed linelength and with this changed measuring crosshairs. With thehelp of this technology the precise dimensions of a measuringspot can be denoted for the first time. This developmentimproves the practical use of products with good opticalperformance.

Switching to Close Focus Mode

Common applications in electrical maintenance and industrialquality control imply optimal measuring distances of about0.75 to 2.5 metres. Additionally, it is often necessary tomeasure distinctly smaller objects at shorter distances.Because of that engineers designed products, which allowfocusing within certain limits. Still, they had not succeeded increating spot sizessmaller than 1 mm.

Infrared thermometerwith lasercrosshairsfor exactspot sizemarking

9

Window material/ features Al2O3 SiO2 CaF2 BaF2 AMTIR ZnS ZnSe KRS5

Recommendedinfraredwavelengthin m 14 12,5 28 2 8 3 14 2 14 2 14 114

Max. windowtemperaturein C 1800 900 600 500 300 250 250 k.A.

Transmissivityin visible area yes yes yes yes no yes yes yes

Resistivenessagainst humidity,acids, ammoniaccombinations very good very good few few good good good good

Appropriate forUHV yes yes yes yes no info yes yes yes


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New products apply a technology which uses two-lens optics:Similar to digital cameras, the inner lens position can beswitched digitally into focusing onto very small spot sizes. Theresult isa very small spot size, butonly ata constantdistance.Ifthe distance grows smaller or longer between measuring spotand infrared thermometer, the measuring spot increases insize. Two laser beams crossing each other create a laser pointdiameter of 1 mm at the smallest spot size position. They helpto show optimal distance as well as spot size. The illustrationshows the optical system of a modern infrared thermometer:Thelens position is selectable andsimultaneouslyvarious lasersighting systems support a real-size display of the measuringspot.

Optomechanical construction of a modern infrared thermometer

ElectronicsDisplays, Outputs and Interfaces

The electronics of the infrared thermometer linearise the outputsignal of the detector in order to generate a linear power signal

0/4 - 20 mA or voltage signal 0 - 10 V. The portable thermome-ters show this signal as a temperature result on the LCD dis-plays. Additionally some of the portable units as well as onlinesensors offer various outputs and interfaces for further signalprocessing.

Outputs andInterfaces

Analog Outputs Digital Outputsuni/bidirectional

Current output RS232/RS4220-20/4-20mA RS4850-5/0-10V FieldbusThermocouple (CAN,Profibus...)

Examples for Outputs and Interfaces of InfraredThermometers

The output interfaces of infrared thermometers may be directly connected with PC, laptop, measuring data printer. PC software allows customer oriented graphicsand tables.

The importance of industrial field bus systems increases moreand more. They allow more flexibility and less cabling and wi-ring efforts. If the manufacturing plans a change in products,the sensor parameters (emissivity, measuring range or limitingvalue) can be adjusted remotely. Consequently, a continuousprocess control andmanagement is guaranteed even in hazar-dous surroundings and with a minimum of labor. If a failure oc-curs, e.g. cable interruptions, drop-out of components, auto-matically an error message appears. A further advantage of in-frared thermometers with digital interface is the possibility tocarry outfield calibrationswith calibration software of themanu-facturer.

Noncontact temperature measurement with infrared thermo-meters is a qualified method of controlling, monitoring and ma-naging process temperatures and of preventive maintenanceof machines and facilities.Portable infrared thermometers or in-frared online sensors, additionally split into point and imagemeasuring products, can be selected depending on the appli-cation.

Generally portable infrared thermometers are used for preven-tive maintenance and inspection of electrical facilities, rotatingmachines as well as a tool for diagnosis for heating, ventilationandair conditioningsystemsandfor thequickanalysisof cars.

Applications of Infrared Thermometers

Portable Infrared Thermometers

Optris

Applications

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Easy andprecise - fast inspection with portable infrared thermometers.The infrared thermometers are also designed for applicationsunder difficult industrial conditions. They might be used insideand outside, in sun and rain, in unsteady temperature condi-tions.The optrisMS - although lightweightandwith thelatest de-sign- isrugged and easyto handle. No matter whetheryoucar-ryit inyourshirt pocket, atthe belt oryou put itintothetoolbox, itshouldalways be with youfor fast inspections.

Portable Optris infrared thermometers

Within only 0.3 seconds you can take temperatures from -32 to530C with an accuracy of 1 % and 1C. Theinstalled laserhelps you toaim atthe measuring object,withonlyone click thetemperature is shown on the display with a resolution of 0.1C. An alarm signal for maximum and minimum values supports asystematic scanning of the measuring object and a quick de-

tection of the hot spot. The new precision optics allow to mea-sure very small objects. If you can approach the measuring ob-ject up to 14 cm, you will have a spot size of only 13 mm. Thespot size increaseswith growing distance.Ata distance (D)of 1meter you can take the temperature of a surface 50 mm in size(S)- consequently, theoptical resolution D:Sis 20:1.

Spot size in mm

Distance in mm

13140

20300

37700

501000

Distance-to-spot-ratio (D:S) 20:1

with the size of 1 mm. Two lasers, which cross each otherdirectly at the close focus point at the distance of 62 mm, helpto aim at the small spot.Up to now thermometers have beenconstructed to either measure at long distancesor to exclusive-ly measure small objects. Thus it was necessary to buy severaltools or exchangeable lenses. The optris LS is an all in one-tool, which enables to focus on close distances by switchinginto theclosefocusmode.

Detailed infrared temperature measurement of an electric control with the helpofthe installedclosefocus opticsfor 1 mm rangesof theoptrisLS

Typical Applications in Maintenance and Service

The optris LS allows very fast inspections: Within 150 ms youcan take temperatures ranging from -32 to 900C. The installedlaser crosshairshelp to exactly aimat themeasuring object andmark the real measuring spot size. Just one click later thetemperature result is shown on the display with a temperatureresolution of 0.1C. A visual and optical alarm signalizes thatvalues either exceeded or dropped below the set limits

(MAX/MIN-function). That way a systematic scanning of theobject and a fast detection of the source of trouble is possible.The new two-lens precision optics of the optris LS alsofacilitates to measure very small objects. Switching into theclose focus mode supports theuser to exactly measure objects

A special sophisticated solution is the smart Flip display of theoptris LS. An integrated position sensor automatically turns theLCD display into the most convenient viewing position forvertical or horizontal measurements. Common infraredthermometers have made it difficult to read the display invertical or upright down positions. The illustration shows such atypically vertical measuring position during the control ofelectronic components. Please note the well visible andautomatically into the best position turned display. Hand heldinfrared thermometers like these with very small measuringspot geometries of 1 mm arean alternative to buyingan infraredthermal imager. Under common conditions - due to highproduction quantities and a high number of testing places - theuse of several infrared thermal imagers at different stations canbe tooexpensive.

Highly accurate infrared temperature measurement with the optris LS of only mmsmallSMD componentsduring a printed circuit boardtesting

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Defective switchgears, fuses, engines and electrical connec-tions are barely visible with the naked eye. But it is commonknowledge, that most production facilities, which consumeelectricity or transfer mechanical power, heat up in case of amalfunction. Non-contact temperature measurement ist animportantinstrumentin preventivemaintenance in order to gua-rantee the safeness of facilities. The optris LS portable thermo-meters offer a spot size of 1 mm, only. Combined with the lasersighting technique they are the ideal tools for quick everydaytemperature measurements of a vast number of measuring ob-jects in a company.

Optical diagram of closefocus optics

temperature difference compared to the evenly chargedcontacts as well as the ambient temperature lead toconclusions on the operating condition. 10 K differenceindicate a badconnection,30 K imply a critical state.

Transformers have a maximum operating temperature. Undulyheating of wiringsof the airtransformer indicatesa malfunction. A reason for that can either be the wiring or an unsteady char-

ging of thephases.

Hidden defects in cables may be localized by a fast scanningwith infrared thermometers. Increased temperatures signalizean increased power consumption. At these points the cablescanbe checkedfor splits, corrosion andaging.

Drafty rooms or bad climate are often the result of defective orunsteady working heating, ventilation and air conditioning sys-tems. The HVAC engineer is asked to locate the source of trou-ble in the shortest possible time and to prevent unscheduledshutoffs. This has been a very time-consuming and troubleso-me work depending on the method. Often the engineer had todrill holes into channels in order to trace leakages in channels,jammed filtersor iced refrigerating coils.The then inserted ther-

mometers took some time to stabilise and to correctly take theair temperature of the conduit. The use of infrared thermome-ters makes this work considerably easier and saves valuableworking time. Surface temperatures of components can nowbe taken from a safe distance in a fast and comfortable way.There is no more need for ladders. HVAC engineers need mea-suring tools, which work efficiently and reliably, which have aruggeddesign andare easy to handle. Theoptris LS supports:

- to detect defective isolations- to find leakages in floor heating systems- to check burners of oil heaters and gas boilers- to control heat exchangers, heating circles as well as

heating distributors- to locate leakages in conduits- to control air outlets and safety valves- to regulate thermostats or to condition the air of a room

Checking the Transformers

Localization of Defective Cables

Typical Applications in Heating, Ventilation and AirConditioning Systems

Optris

Applications

- Temperature measurements of moving machines andfacilities, electrical connections of engines and of objects inhazardous surroundings

- Detection of loose connection joints- Localization of hidden failures in cable channels- Inspection of fuses and circuit breakers- Monitoring the low and medium voltage facilities- Detection of one-sided overload and unbalanced

energy distribution- Checking transformers and small components

During the transfer of high electrical performance bus contactsoften show unbalanced load distribution and overheating,which might be a safety risk. Mechanical movement of materialmay result in loose contacts, which - due to cyclic heating andcooling - increase their electrical resistance, which leads to ahigherpower consumption andgenerates more heat. Also dustand corrosion may be reasons for higher resistance. The

Temperature Measurement of Contacts


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13

Checking the temperature of heating circles

Controlling the Air Conduits

Checking the Outlets for Supply Air and Extracted Air

Regulating the Condition of the Air of a Room

Checking Burners

Air conduit joints are often sources of trouble. They either loo-

sen because of vibrations or because of the constant expansi-on andcontraction of theconduitswhen cold andwarm air runsthrough. Cracks may lead to a overloaded climate aggregateand may shorten their durability. Regular controls of the con-duits with infrared thermometers support to detect and monitorunbalanced temperature distribution (increase or drop of tem-peratures) which may lead to leakages, cracks or indicate de-fective isolation.

Differences in temperatures between supply and extracted airindicate malfunctions. 10 to 12 K are normal in cooling proces-ses. If values rise above 12 K too few air might be running andthe cooling liquid might be too cold. If values drop below 10 Kthey indicate jammed refrigerating coils, where the cooling li-quid cannot pass. Temperatures in heating systems may varybetween 15 and40 K. If temperaturesshow more variation, jam-med filters or malfunction in heat exchangers may be the rea-son.

The engineer needs detailed information on the temperaturedistribution inside a room in order to dimension climate aggre-

gates or evaluate air outlets. With an optris infrared thermome-ter walls, ceilings and floors can be scanned in seconds. Justaimat themeasuring surface and thetemperature is displayed.With the help of the measuring data the HVAC engineer is ableto create the optimal climate. Thus, optimal ambient conditionshelp to protect devices andfacilitiesandfurthermorebuild a he-althyclimate for the employees.

Infrared temperature measurement helps to check burners ofoil heating systems and gas boilers. The results offer informati-on on thesources of trouble. Increasedtemperatures imply jam-med heat exchangers and polluted surfaces on the side of theflame.

Typical Applications of Car Analysis

The important factor is to locate and mend sources of troubleas quickly as possible.Please find here some examples of howto use non-contact temperature measurement in order toprevent repetitiveexchange of expensive components:

Analysisof- malfunction in engines- overheating of catalyticconverters- engine managementsystem- air conditioningsystem- cooling systemor- braking system.

Checking the heating system

Checking the Functionality of Brakes and Tyres

Controlling the Heating

Checking the Air Conditioning System

In order to check the reason for an unsteady braking behavior,drive thecar straight ahead andbrake.Instantly take thetempe-rature of the brake drums and disks. Big temperature differen-ces indicate jammed brake calipers and brake pistons, whichhavefunctioningproblems.

Check the temperature of the cooling liquid at the upper end ofthepipe when theengine is warm. If thetemperaturedropsnota-

bly below 95Cthe thermostat might not close. Afterwards takethe temperatures of input and output of the pipes of the splatte-ring wall. A 20 K increase in temperatures at the supply is nor-mal. A cold outlet pipe implies that no cooling liquid runsthrough the heating system. Either the heat exchanger is jam-medor theheating control spool isclosed.

Check the performance of the cooling system of a running airconditioning system by taking the temperature of the air con-duits in the inside of the car. Compare the measuring resultswith the specifications of the manufacturer. A balanced tempe-rature distribution at theoutlets of the air conduits provides for acomfortableclimate.


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11

11

Analysis of the Cooling System

The enginerunswarm,but you cannotfinda leakage inthe coo-ling system. Causes for that could be various: a jammed radi-ator block, a defective fan sensor, a defective thermostat or aworn out rotor in the coolant pump. You already checked thecooler, cooling liquid sensor and catalytic converter. The ther-mostat needs to be controlled with the engine idling warm inneutral gear. Afterwards take the temperature of the upper endof the cooling pipe and of the thermostat housing. With the en-gine reaching a temperature of 80 to 105C, the thermostatshould open and you should see a temperature increase in theupper end of the cooling pipe. If the values remain unchanged,no cooling liquid is running and the thermostat can be locatedassourceof problem.

- easyto handle- work non-contactand deliver precise measurementresultswithinseconds

- carry out safe inspections on hot components or objects inhazardous surroundings

- locatesources of problem without exchangingcomponents- detectweak pointsbefore they becomea problem- save valuable time andmoney

Online infrared temperature sensors applicable for quality ma-nagement purposes in production lines. In addition to the non-contact temperature measurement and the display of theresults the user is able to control and manage the process tem-peratures. The wide range of possibilities to adjustinfrared sen-sors to the measuring task allows an easy upgrade in existingproduction facilities as well as in the long-term planned equip-ment in cooperation with OEM customers in the machineconstruction industry.Manifold applications are:

- plasticsprocessing- glassprocessing- paperprocessing- in printing plants- in laser weldingand cutting processes- measurements of electronic components

Advantages of Infrared Thermometers:

Online Infrared Thermometers

Typical Applications for Online Infrared Thermometers

Online infrared thermometers are used to control thetemperature of paper web and the application of glue during

the manuacturing of corrugated paper

The high production speed of running paper web in modernlaminating facilities require a precise and fast control of thepaper temperature, of the glue and of the basic product, whichneeds to be concealed. An accurate laminating is onlypossible, if the necessary temperature balance for this processistakencareof atall times.

Temperature monitoring and managing of temperatures of prin-ting machines with miniaturized infrared temperature sensors

from Optris

Controlling the Temperature of Electronic Components duringFunction Tests

The use of miniaturized infrared temperature sensors fromOptris along the paper web of the press-on roller and along themachine applying the glue in order to monitor and manage thetemperatures support a steady laminating process. Air purgingand cleaning processes on the optical channels of the infraredsensors support a maintenance-free measurement. The intelli-gent signal processing of the infrared sensors right along thetrack facilitate a geometrical correction of the glue applicationprocess.

Increasingly more manufacturers of electronic componentsand PCB's use non-contact temperature measurement in orderto monitor andcheckthe thermal behavior of their products.

Infrared temperature measurement of wafers and electronic components

Infrared temperature measurement in paper and cardboard processing

Optris

Applications

14


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Infrared cameras support a detailed real-time analysis of thethermal reaction of circuit boards in research and developmentas well as in serial production. Under certain circumstanceshigh production numbers and the increasing number of testandcalibration stations make the use of infrared thermal came-ras too expensive. The miniaturized infrared temperature sen-sors optris CT can be applied for serial monitoring of criticalcomponents in production facilities. The result is at once com-municated to the test desk for further decision making. Thatway smallest spot sizes of only 0,6 mm can be monitored withan optrisCT andan installedfocuslens.

To join and cut with the help of lasers appears to be a very so-phisticated, cost- and time-effective technology. These pro-cesses use the precision of lasers and a high energy concen-tration. More accuracy on the cutting edge and shorter retenti-on times combined with a higher temperature require a highquality product handling and compensation routine. Expansion

in length according to temperature changes is one result for adeterioration in accuracy.

Monitoring the Product Temperature in Laser Welding andLaser Cutting Processes

The miniaturized infrared temperature sensors optris CT mea-sure the product temperature at the cutting or joining edge veryquickly and react with corresponding correction signals. Theoptris CT and an installed focus lens can measure small spotsof 0.6 mm. Thus production engineers have a measurementand control system, which works continuously and monitorsthetemperaturereactionof theproductsin order to:- quickly adjust and startfacilitiesduring batchchanges,

reducing idle times andtestmaterial- monitor and recordbatch production- guaranteea high andconstantprocessquality

Thermal Imagers

The use of portable thermal imagers is increasingly importantfor preventive maintenance. As anomalies and malfunction onsensitive and important facility components often show with aheat radiation, the consequent and directed use of thistechnology helps to prevent high consequential costs, whichmightbe theresult of machine failure andproduction stops.

The latest thermal imagers are small, lightweight, are easy touse and have good ergonomics. The integrated LCD displaysupports the data analysis on site in order to decide on appro-priate maintenance methods at once and to carry out repairs. According to the environmental rating IP54 the systems are sa-fe against environmental influencesuch asdust andsplattering water and therefore are best equipped for the indu-strial use. The thermal imagers take temperatures ranging from-20 and 350C (optionally to 900C). The systems accuracy is 2 % or 2C of the reading. A logically built menu supportsthe easy adjustment of basic features such as choosing the co-lors, setting date and time, emissivity. It also helps to changebetween automatic and manual set-up and to organize the sto-

red thermal images.

The high quality Vanadium oxide detectors are safe againsthigh radiation, dazzling sunlight andhot objects,which areacci-dentally included in the image. Consequently, measurementscan be safely carried out outside and with direct light. The ima-ge rating of 50 Hz combined with a high thermal resolution of< 0.1 K help to catch even small temperature discrepancies inreal time, even if objects are moving or different objects are ai-medat in fast sequence.

Due to the high thermal sensitivity the detector shows the sur-roundings of the measuring objects in high contrast.Thishelpsto better orientate in the thermal image. Additionally, the laserprovides an improved localization and targeting of the monito-ringpoints.

The Infrared Detector Infrared temperature measurement in laser welding processes

Thermal imagers

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12

Smart Camera

The temperature resultis shown on thedisplay with a resolutionof 0.1C. Furthermore, crosshairs mark the measuring point inthe display. Thus, the user may in a first step obtain anoverviewof the electric switch box. In a second step hecan control singlecomponents such as electrical connections, contacts or con-tactors and record them. Very small objects, as for instance cir-cuits or SMD components on printed circuit boards, are bettercontrolled with an infrared camera, as the aiming at such smallobjects requires either a tripod or much patience. Infrared ca-meras can be switchedintoa mode, which helps tofindthema-ximum temperature:Inside a defined squareimagecutout allpi-xels are itemised and their temperatures are shown on the dis-play. This very helpful function allowsto determinethe tempera-

ture of tiny objects. Optional to the maximum result, the displayalso shows minimum or average result.

Temperaturecontrolon a circuitwith maximumfunction

The camera stores the infrared images in JPG format includingallradiometric data of each singlepixel for further processing ordocumentation purposes. An integrated USB interfacesupports the transfer of the data to PC or laptop. The providedsoftware allows the analysis of the results. An integrated videointerface (EU standard PAL) makes the presentation of imagesandvideosequenceson an externalmonitor easy.

Three different exchangeable lenses are available for variousmeasuring distances between camera and object. Thus, theuser canchoosethe optimal adjustment for hisapplication. Thestandard lens for medium distances is a 25-lens. With its opti-mized field of viewit can be usedfor all standardeverydaymea-surements, as there are the control of mechanical systems like

Exchangeable Lenses for Manifold Applications

bearings,waves and drive units, the inspection of conduits andisolationsas well as classicalbuilding thermography.The 9-tele lens is appropriate for measuring objects at a longerdistance with a high detailed resolution of single components(e.g. controlling switches and insulators in high voltage facili-ties).The 34-wide-angle lens completes the supply and providesthe monitoring of medium-sized electric switch boards at oneglance in narrow circumstances as they often are in manufac-turingfacilities. Thus, the camerastill coversan area of 1.50 m x1.40 m even at a distance of only 2 m between measuring ob-ject andlens. A further important application is the measurement of verysmallSMD componentson printed circuit boards.

For that purpose the 34-lens can be focused on very short dis-tances of less than 50 mm. The so achieved resolution enablesthe user to determine temperatures of objects of only 0.5 mmdiameter.

Thermographic solutions are completed with software for theonline video display and recording of fast thermodynamic pro-cesses with manifold tools for picture analysis. Comfortabletransfer and management of data from the infrared camera aswell as subsequent analysis of the radiometric data of the infra-red images support the processing of the temperature results.

Temperature information can be displayed for each single ima-ge pixel. Subsequent adjustment of colors as well as setup ofthe color palette help to customize the data to the requirementsof the analysis. Emissivities and ambient temperatures may beadjusted accordingly. Afterwards the reports are saved asWORD or PDF files. The user is able to share his results aboutthe analysed thermal process withhis colleagues.

Software of Thermal Imagers and Thermographic Solutions

Optris

Thermal Imagers

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Recommended Literature:

/1/ VDI/VDE Richtlinie, Technische Temperaturmessungen -Spezifikation von Strahlungsthermometern, Juni 2001, VDI 3511 Blatt 4.1

/2/ Stahl, Miosga: Grundlagen Infrarottechnik, 1980,Dr. Alfred Htthig Verlag Heidelberg

/3/ Walther, Herrmann: Wissensspeicher Infrarotmesstechnik,1990, Fachbuchverlag Leipzig

/4/ Walther, L., Gerber, D:. Infrarotmesstechnik, 1983, Verlag Technik Berlin

/5/ De Witt, Nutter: Theory and Practice of RadiationThermometry,1988, John Wiley & Son, New York,ISBN 0-471-61018-6

/6/ Wolfe, Zissis: The Infrared Handbook, 1978,Office of Naval Research, Department of the Navy,Washington DC.

Addendum

Emissivity Tablesfrom Optris InfraSight Plus manual

Glossary

from Optris InfraSight Plus manual

Selection criteria for infrared thermometers

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Glossar

Optris

Addendum: Glossary, Emissivity Tables

18

Term Explanation

Absorption

Ratio of absorbed radiation by anobject to incoming radiation. A

number between 0 and 1.

Emissivity

Emitted radiation of an objectcompared to the radiation from ablack bodysource. A numberbetween 0 and 1.

FilterMaterial, permeable for certaininfrared wavelengths only

FOVField of view: Horizontal field of viewof an infrared lens.

FPAFocal Plane Array: type of aninfrared detector.

Grey Body Source

An object, which emits a certain partof the energy which a black bodysource emits at every wavelength.

IFOV

Instantaneous field of view: A valuefor the geometric resolution of athermal imager.

NETD

Noise equivalent temperaturedifference. A value for the noise (inthe image) of a thermal imager.

Object parameter

Values, with which measurementconditions and measuring object aredescribed (e.g. emissivity, ambienttemperature, distance a.s.o.)

Object signal

A noncalibrated value, which refersto the radiation the thermal imagerreceives from the measuring object.

Palette Colors of the infrared image

PixelSynonym for picture element. Asingle picture point in an image.

Term Explanation

Reference temperatureTemperature value to compareregular measuring data with.

Reflection

Ratio of radiation reflected by theobject and incoming radiation. Anumber between 0 and 1.

Black body source

Object with a reflection of 0. Anyradiation is to be traced back to itstemperature.

Spectral specificradiation

Energy emitted by an object relatedto time, area and wavelength(W/m/m).

Specific radiation

Energy emitted from an object

related to units of time and area(W/m).

Radiation

Energy emitted by an object relatedto time, area and solid angle(W/m/sr).

Radiation flowEnergy emitted by an object relatedto the unit of time (W)

Temperature difference

A value, which is determined bysubtraction of two temperaturevalues.

Temperature range

Current temperature measuringrange of a thermal imager. Imagerscan have several temperatureranges. They are described with thehelp of two black body sourcevalues, which serve as thresholdvalues for the current calibration.

Thermogram Infrared image

Transmissity

Gases and solid states havedifferent transmissivities.Transmissivity describes the level ofinfrared radiation, which permeatesthe object. A number between 0 and

1.

Ambient surroundingsObjects and gases, which passradiation to the measuring object.


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Emissivity Tables

In the following you will find a list of emissivities from technicalliterature and from measurements carried out by the OptrisGmbH.

References

1Mikal A. Bramson: Infrared Radiation, A Handbook for Applications,Plenum Press, N.Y.

2William L. Wolfe, George J. Zissis: The Infrared Handbook, Office ofNaval Research, Department of Navy, Washington, D.C.

3

Madding, R.P.: Thermographic Instruments and Systems. Madison,Wisconsin: University of Wisconsin - Extension, Department ofEngineering and Applied Science

4William L. Wolfe: Handbook of Military Infrared Technology, Office ofNaval Research, Department of Navy, Wahsington, D.C.

5

Jones, Smith, Probert: External thermography of buildings , Proc. Ofthe Society of Phot-Optical Instrumentation Engineers, vol. 110,Industrial and Civil Applications of Infrared Technology, Juni 1977London

6Paljak, Pettersson: Thermography of Buildings, Swedish BuildingResearch Institute, Stockholm 1972

7

Vlcek, J.: Determination of emissivity with imaging radiometers andsome emissivities at = 5 m. Photogrammetric Engineering andRemote Sensing.

8

Kern: Evaluation of infrared emission of clouds and ground asmeasured by weather satellites, Defence Documentation Center, AD617 417.

9

hman, Claes: Emittansmtningar med AGEMA E-Box. Tekniskrapport, AGEMA 1999. (Emissionsmessungen mit AGEMA E-Box.Technischer Bericht, AGEMA 1999.)

19

Tables

Legends: 1: material, 2: specification, 3: temperature in C,4: spectrum, T: total spectrum SW: 2 - 5 m, LW: 8 - 14 m,LLW:6,5- 20m,5: emissivity, 6: references

1 2 3 4 5 6 Aluminum-brass 20 T 0.6 1

AluminumPlate, 4 samplesdifferently scratched 70 LW 0.03 - 0.06 9

AluminumPlate, 4 samplesdifferently scratched 70 SW 0.05 - 0.08 9

Aluminumanodized, light grey,dull 70 LW 0.97 9

Aluminumanodized, light grey,dull 70 WS 0.61 9

Aluminumanodized, light grey,dull 70 LW 0.95 9

Aluminumanodized, light grey,dull 70 SW 0.67 9

Aluminum anodized plate 100 T 0.55 2 Aluminum film 27 3 m 0.09 3 Aluminum film 27 10 m 0.04 3 Aluminum harshened 27 3 m 0.28 3 Aluminum harshened 27 10 m 0.18 3 Aluminum Cast, sandblasted 70 LW 0.46 9 Aluminum Cast, sandblasted 70 SW 0.47 9

Aluminumdipped in HNO3,plate 100 T 0.05 4

Aluminum polished 50 - 100 T 0.04 - 0.06 1 Aluminum polished, plate 100 T 0.05 2

1 2 3 4 5 6 Aluminum polished plate 100 T 0.05 4 Aluminum harshened surface 20 - 50 T 0.06 - 0.07 1 Aluminum deeply oxidized 50 - 500 T 0.2 - 0.3 1

Aluminumdeeply weatherbeaten 17 SW 0.83 - 0.94 5

Aluminum unchanged, plate 100 T 0.09 2 Aluminum unchanged, plate 100 T 0.09 4 Aluminum vacuumcoated 20 T 0.04 2

Aluminum-oxide activated, powder T 0.46 1 Aluminum-hydroxide powder T 0.28 1 Aluminum-oxide

clean, powder(aluminumoxide) T 0.16 1

Asbestos Floor tiles 35 SW 0.94 7 Asbestos Boards 20 T 0.96 1 Asbestos Tissue T 0.78 1 Asbestos Papier 40 - 400 T 0.93 - 0.95 1 Asbestos Powder T 0.40 - 0.60 1 Asbestos brick 20 T 0.96 1 Asphaltroad surface 4 LLW 0.967 8

Brass

treated with 80-

sandpaper 20 T 0.2 2Brass plate, milled 20 T 0.06 1

Brassplate, treated withsandpaper 20 T 0.2 1

Brass stron lgy polished 100 T 0.03 2Brass oxidized 70 SW 0.04 - 0.09 9Brass oxidized 70 LW 0.03 - 0.07 9Brass oxidized 100 T 0.61 2Brass ox idized at 600C 200 - 600 T 0.59 - 0.61 1Brass polished 200 T 0.03 1Brass blunt, patchy 20 - 350 T 0.22 1Brick Aluminumoxide 17 SW 0.68 5

BrickDinas-Siliziumoxide,fireproof 1000 T 0.66 1

BrickDinas-Siliziumoxid,glazed, harshened 1100 T 0.85 1

BrickDinas-Siliziumoxid,unglazed, harshened 1000 T 0.8 1

Brickfireproof product,corundom 1000 T 0.46 1

Brickfireproof product,magnesit 1000 - 1300 T 0.38 1

Brickfireproof product,mildly beaming 500 - 1000 T 0.65 - 0.75 1

Brickfireproof product,strongly beaming 500 - 1000 T 0.8 - 0.9 1

Brick fire brick 17 SW 0.68 5Brick glazed 17 SW 0.94 5Brick brickwork 35 SW 0.94 7

Brick brickwork, plastered 20 T 0.94 1Brick normal 17 SW 0.86 - 0.81 5Brick red, normal 20 T 0.93 2Brick red, grey 20 T 0.88 - 0.93 1Brick chamotte 20 T 0.85 1Brick chamotte 1000 T 0.75 1Brick chamotte 1200 T 0.59 1

Brickamorphous silicon95% SiO2 1230 T 0.66 1

BrickSillimanit, 33% SiO2,64% Al2O3 1500 T 0.29 1

Brick waterproof d17 SW 0.87 5Bronze Phosphorbronze 70 LW 0.06 9Bronze Phosphorbronze 70 SW 0.08 1

Bronze polished 50 T 0.1 1Bronze Porous, harshened 50 - 100 T 0.55 1Bronze powder T 0.76 - 0.80 1Carbon fluent 20 T 0.98 2


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Optris

Addendum

20

1 2 3 4 5 6Carbon p lumbago powder T 0.97 1Carbon charcoal powder T 0.96 1Carbon candle soot 20 T 0.95 2Carbon lamp soot 20 - 400 T 0.95 - 0.97 1Cast Iron treated 800 - 1000 T 0.60 - 0.70 1Cast Iron f luent 1300 T 0.28 1Cast Iron cast 50 T 0.81 1

Cast Ironblocks made of castiron 1000 T 0.95 1

Cast I ron oxid ized 38 T 0.63 4Cast I ron oxid ized 100 T 0.64 2Cast I ron oxid ized 260 T 0.66 4

Cast I ron oxid ized 538 T 0.76 4Cast Iron oxidized at 600C 200 - 600 T 0.64 - 0.78 1Cast I ron polished 38 T 0.21 4Cast I ron polished 40 T 0.21 2Cast I ron polished 200 T 0.21 1Cast Iron untreated 900 - 1100 T 0.87 - 0.95 1Chipboard untreated 20 SW 0.9 6Chrome polished 50 T 0.1 1Chrome polished 500 - 1000 T 0.28 - 0.38 1Clay burnt 70 T 0.91 1Cloth black 20 T 0.98 1Concrete 20 T 0.92 2Concrete pavement 5 LLW 0.974 8Concrete harshened 17 SW 0.97 5

Concrete dry 36 SW 0.95 7

Copperelectrolytic, brightlypolished 80 T 0.018 1

Copper electrolytic, polished -34 T 0.006 4Copper scraped 27 T 0.07 4Copper molten 1100 - 130 0 T 0.13 - 0.15 1Copper commercial, shiny 20 T 0.07 1Copper oxidized 50 T 0.6 - 0.7 1Copper oxidized , dark 27 T 0.78 4Copper oxidized , deeply 20 T 0.78 2Copper oxidized , b lack T 0.88 1Copper polished 50 - 100 T 0.02 1Copper pollished 100 T 0.03 2

Copper polished, commercial 27 T 0.03 4

Copper polished, mechanical 22 T 0.015 4

Copperclean, thoroughlyprepared surface 22 T 0.008 4

Copper-dioxide powder T 0.84 1Copper-dioxide r ed, powder T 0.7 1Earth saturated with water 20 T 0.95 2Earth dry 20 T 0.92 2Enamel 20 T 0.9 1Enamel paint 20 T 0.85 - 0.95 1Fiberboard hard, untreated 20 SW 0.85 6Fiberboard Ottrelith 70 LW 0.88 9

Fiberboard Ottrelith 70 SW 0.75 9Fiberboard particle plate 70 LW 0.89 9Fiberboard particle plate 70 SW 0.77 9Fiberboard porous, untreated 20 SW 0.85 6

1 2 3 4 5 6GlazingRebates

8 different colors andqualities 70 LW 0.92 - 0.94 9

GlazingRebates

8 different colors andqualities 70 SW 0.88 - 0.96 9

GlazingRebates

aluminum, differentage 50 - 100 T 0.27 - 0.67 1

GlazingRebates

on oily basis, averageof 16 colors 100 T 0.94 2

GlazingRebates chrome green T 0.65 - 0.70 1GlazingRebates cadmium yellow T 0.28 - 0.33 1Glazing

Rebates cobal t blue T 0.7 - 0.8 1GlazingRebates plastics, black 20 SW 0.95 6GlazingRebates plastics, white 20 SW 0.84 6GlazingRebates oil 17 SW 0.87 5GlazingRebates oil, different colors 100 T 0.92 - 0.96 1GlazingRebates o il , shiny grey 20 SW 0.96 6GlazingRebates o il , g rey, matt 20 SW 0.97 6GlazingRebates oil, black, matt 20 SW 0.94 6Glazing

Rebates oil, black, shiny 20 SW 0.92 6Gold brightly polished 200 - 600 T 0.02 - 0.03 1Gold strongly polished 100 T 0.02 2Gold polished 130 T 0.018 1Granite polished 20 LLW 0.849 8Granite harshened 21 LLW 0.879 8

Graniteharshened, 4 differentsamples 70 LW 0.77 - 0.87 9

Graniteharshened, 4 differentsamples 70 SW 0.95 - 0.97 9

Gypsum 20 T 0.8 - 0.9 1Gypsum,applied 17 SW 0.86 5Gypsum,applied

gypsum plate,untreated 20 SW 0.9 6

Gypsum,applied harshened surface 20 T 0.91 2

Ice: see Water

Iron and Steel electrolytic 22 T 0.05 4



Iron and Steelelectrolytic, brightlypolished 175 - 225 T 0.05 - 0.06 1

Iron and Steel freshly milled 20 T 0.24 1

Iron and Steelfreshly processed withsandpaper 20 T 0.24 1

Iron and Steel smoothed plate 950 - 1100 T 0.55 - 0.61 1

Iron and Steelforged, brightlypolished 40 - 250 T 0.28 1


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21

1 2 3 4 5 6Nickel electr olytic 260 T 0,07 4Nickel electr olytic 538 T 0,1 4Nickel galvanized, polished 20 T 0,05 2

Nickelgalvanized on iron,not polished 20 T 0,11 - 0,40 1

Nickelgalvanized on iron,non polished 22 T 0,11 4

Nickelgalvanized on iron,non polished 22 T 0,045 4

Nickel lightly matt 122 T 0,041 4Nickel oxidized 200 T 0,37 2Nickel oxidized 227 T 0,37 4Nickel oxidized 1227 T 0,85 4Nickel oxidized at 600C 200 - 600 T 0,37 - 0,48 1Nickel polished 122 T 0,045 4Nickel clean, pol ished 100 T 0,045 1Nickel clean, pol ished 200 - 400 T 0,07 - 0,09 1Nickel-chrome wire, bare 50 T 0,65 1Nickel-chrome wire, bare 500 - 1000 T 0,71 - 0,79 1Nickel-chrome wire, oxidized 50 - 500 T 0,95 - 0,98 1

Nickel-chrome milled 700 T 0,25 1Nickel-chrome sandblasted 700 T 0,7 1Nickeloxide 500 - 650 T 0,52 - 0,59 1Nickeloxide 1000 - 1250 T 0,75 - 0,86 1

Oil,Lubricating Oil 0,025-mm-layer 20 T 0,27 2



Oil,Lubricating Oil thick layer 20 T 0,82 2

Oil,Lubricating Oil

layer on Ni-basis: onlyNi-Basis 20 T 0,05 2

Paint3 colors, sprayed onaluminum 70 LW 0,92 - 0,94 9

Paint3 colors, sprayed onaluminum 70 SW 0,50 - 0,53 9

Paintaluminum onharshened surface 20 T 0,4 1

Paint bakelite 80 T 0,83 1Paint heat-proof 100 T 0,92 1

Paintblack, shiny, sprayedon iron 20 T 0,87 1

Paint black, matt 100 T 0,97 2Paint black, blunt 40 - 100 T 0,96 - 0,98 1Paint white 40 - 100 T 0,8 - 0,95 1Paint white 100 T 0,92 2Paper 4 di fferent colors 70 LW 0,92 - 0,94 9Paper 4 di fferent colors 70 SW 0,68 - 0,74 9

Papercoated with blackpaint T 0,93 1

Paper dark blue T 0,84 1Paper yellow T 0,72 1Paper green T 0,85 1Paper red T 0,76 1Paper black T 0,9 1Paper black, blunt T 0,94 1Paper black, blunt 70 LW 0,89 9

Paper black, blunt 70 SW 0,86 9Paper white 20 T 0,7 - 0,9 1

Paperwhite, 3 different shinycoatings 70 LW 0,88 - 0,90 9

1 2 3 4 5 6

Iron and Steel milled plate 50 T 0.56 1

Iron and Steel shiny, etched 150 T 0.16 1

Iron and Steelshiny oxide layer,plate 20 T 0.82 1

Iron and Steel hotly milled 20 T 0.77 1

Iron and Steel hotly milled 130 T 0.6 1

Iron and Steel coldly milled 70 LW 0.09 9

Iron and Steel coldly milled 70 SW 0.2 9

Iron and Steel covered with red rust 20 T 0.61 - 0.85 1

Iron and Steel oxidized 100 T 0.74 1


Iron and Steel oxidized 125 - 525 T 0.78 - 0.82 1


Iron and Steel oxidized 200 - 600 T 0.8 1


Iron and Steel polished 100 T 0.07 2

Iron and Steel polished 400 - 1000 T 0.14 - 0.38 1

Iron and Steel polished plate 750 - 1050 T 0.52 - 0.56 1

Iron and Steelharshened, evensurface 50 T 0.95 - 0.98 1

Iron and Steel rusty, red 20 T 0.69 1

Iron and Steel rusty red, plate 22 T 0.69 4

Iron and Steel deeply oxidized 50 T 0.88 1

Iron and Steel deeply oxidized 500 T 0.98 1

Iron and Steel deeply rusted 17 SW 0.96 5

Iron and Steel deeply rusted plate 20 T 0.69 2

Iron galvanized plate 92 T 0.07 4

Iron galvanized plate, oxidized 20 T 0.28 1

Iron galvanized plate, oxidized 30 T 0.23 1

Iron galvanized deeply oxidized 70 LW 0.85 9

Iron galvanized deeply oxidized 70 SW 0.64 9Iron tinned plate 24 T 0.064 4L eather tanned fur T 0.75 - 0.80 1Limestone T 0.3 - 0.4 1Magnesium 22 T 0.07 4Magnesium 260 T 0.13 4Magnesium 538 T 0.18 4Magnesium polished 20 T 0.07 2Magnesium-powder T 0.86 1Molybdenum 600 - 1000 T 0.08 - 0.13 1Molybdenum 1500 - 2200 T 0.19 - 0.26 1Molybdenum twine 700 - 2500 T 0.1 - 0.3 1Mortar 17 SW 0.87 5

Mortar dry 36 SW 0.94 7Nickel wire 200 - 1000 T 0.1 - 0.2 1Nickel elect rolytic 22 T 0.04 4Nickel elect rolytic 38 T 0.06 4


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Optris

Emissivity Tables, Selection Criteria

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1 2 3 4 5 6

Paperwhite, 3 different shinycoatings 70 SW 0.76 - 0.78 9

Paper white, bonded 20 T 0.93 2

Plasticsfiber optics laminate(printed circuit board) 70 LW 0.91 9

Plasticsfiber optics laminate(printed circuit board) 70 SW 0.94 9

Plasticspolyurethane-insulating plate 70 LW 0.55 9

Plasticspolyurethane-insulating plate 70 SW 0.29 9

PlasticsPVC, plastic floor,blunt, structured 70 LW 0.93 9

PlasticsPVC, plastic floor,blunt, structured 70 SW 0.94 9

Plate shiny 20 - 50 T 0.04 - 0.06 1Plate white plate 100 T 0.07 2Platinum 17 T 0.016 4Platinum 22 T 0.05 4Platinum 260 T 0.06 4Platinum 538 T 0.1 4Platinum 1000 - 1500 T 0 .14 - 0.18 1Platinum 1094 T 0.18 4Platinum band 900 - 1100 T 0.12 - 0.17 1Platinum wire 50 - 200 T 0.06 - 0.07 1Platinum wire 500 - 1000 T 0.10 - 0.16 1Platinum wire 1400 T 0.18 1Platinum clean, polished 200 - 600 T 0.05 - 0.10 1Plumb shiny 250 T 0.08 1

Plumb non oxidized, pol ished 100 T 0.05 4Plumb oxidized, g rey 20 T 0.28 1Plumb oxidized, g rey 22 T 0.28 4Plumb oxidized at 200C 200 T 0.63 1Plumb rot 100 T 0.93 4Plumb rot,Powder 100 T 0.93 1Polystyrene heat insulation 37 SW 0.6 7Porcelain glazed 20 T 0.92 1Porcelain white, glowing T 0.70 - 0.75 1Rubber hard 20 T 0.95 1

Rubber soft, grey, harshened 20 T 0.95 1Sand T 0.6 1Sand 20 T 0.9 2Sandpaper coarse 80 T 0.85 1Sandstone polished 19 LLW 0.909 8Sandstone harshened 19 LLW 0.935 8Silver polished 100 T 0.03 2Silver clean, polished 200 - 600 T 0.02 - 0.03 1Skin Human Being 32 T 0.98 2Slag basin 0 - 100 T 0.97 - 0.93 1Slag basin 200 - 500 T 0.89 - 0.78 1Slag basin 600 - 1200 T 0.76 - 0.70 1Slag basin 1400 - 1800 T 0 .69 - 0.67 1Snow: seeWater

Stainless Steel plate, polished 70 LW 0.14 9

Stainless Steel plate, polished SW 0.18 9

1 2 3 4 5 6

Stainless Steelplate, not treated,scratched 70 LW 0.28 9

Stainless Steelplate, not treated,scratched 70 SW 0.3 9

Stainless Steel milled 700 T 0.45 1Stainless Steel alloy, 8% Ni, 18% Cr 500 T 0.35 1Stainless Steel sandblasted 700 T 0.7 1Stainless Steel type 18-8, shiny 20 T 0.16 2

Stainless Steeltype 18-8, oxidized at800C 60 T 0.85 2

Stukkaturharshened, yellowgreen Okt 90 T 0.91 1

Tar T 0.79 - 0.84 1Tar paper 20 T 0.91 - 0.93 1Titanium oxidized at 540C 200 T 0.4 1

Titanium oxidized at 540C 500 T 0.5 1Titanium oxidized at 540C 1000 T 0.6 1Titan ium poli shed 200 T 0.15 1Titan ium poli shed 500 T 0.2 1Titan ium poli shed 1000 T 0.36 1Tungsten 200 T 0.05 1Tungsten 600 - 1000 T 0.1 - 0.16 1Tungsten 15 00 - 220 0 T 0.24 - 0.31 1Tungs ten twine 3300 T 0.39 1

Varnishon parquet flooringmade of oak 70 LW 0.90 - 0.93 9

Varnishon parquet flooringmade of oak 70 SW 0.9 9

Varnish matt 20 SW 0.93 6

Vulcanite T 0.89 1

Wall Paperslightly patterned, lightgrey 20 SW 0.85 6

Wall Paper slightly patterned, red 20 SW 0.9 6Water distilled 20 T 0.96 2

Waterice, strongly coveredwith frost 0 T 0.98 1

Water ice, slippery -10 T 0.96 2Water ice, slippery 0 T 0.97 1Water frost crystals -10 T 0.98 2

Wate r coate d >0.1 mm thick 0 - 100 T 0.95 - 0.98 1Water snow T 0.8 1Water snow -10 T 0.85 2

Wood 17 SW 0.98 5Wood 19 LLW 0.962 8Wood planed 20 T 0.8 - 0.9 1Wood planed oak 20 T 0.9 2Wood planed oak 70 LW 0.88 9Wood planed oak 70 SW 0.77 9

Woodtreated withsandpaper T 0.5 - 0.7 1

Woodpine, 4 differentsamples 70 LW 0.81 - 0.89 9

Woodpine, 4 differentsamples 70 SW 0.67 - 0.75 9

Wood plywood, even, dry 36 SW 0.82 7Wood plywood, untreated 20 SW 0.83 6Wood white, damp 20 T 0.7 - 0.8 1

Zinc plate 50 T 0.2 1Zinc oxidized at 400C 400 T 0.11 1Zinc oxidized surface 10 00 - 120 0 T 0.50 - 0.60 1Zinc polished 200 - 300 T 0.04 - 0.05 1


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Selection Criteria for Infrared Thermometers

Temperature Range

Environmental Conditions

Spot Size

Material and Surface of the Measuring Object

Response Time of Infrared Thermometers

Interfaces for the Signal Output

A wide selection of infrared thermometers is available for non-contact temperature measurement. The following criteria willhelp to find theoptimalmeasuringdevice foryour application.- Temperature range

- Environmental conditions- Spot size- Material and surface of the measuring object

- Response time of the infrared thermometer- Interface

Choose the temperature range of the sensor as optimal aspossible in order to reach a high resolution of the objecttemperature. The measuring ranges can be adjusted to themeasuring taskmanually or via digital interface.

The maximum acceptable ambient temperature of the sensorsis very important. The optris CT line operates in up to 180Cwithout any cooling. By using water and air cooling themeasuring devices work in even higher ambient temperatures. Air purge systems help to keep the optics clean from additionaldustin the atmosphere.

The size of the measuring object has to be equal to or biggerthan the viewing field of the sensor in order to reach accurateresults. The spot diameter (S) changes accordingly to thedistance of the sensor (D). The brochures specify the D:Srelation for the different optics.

The emissivity depends on material, surface and other factors.The common rule reads as follows: The higher the emissivity,the easier the measurement generates a precise result. Manyinfrared thermometers offer the adjustment of the emissivity.The appropriate values can be taken from the tables in theaddendum.

The response time of infrared thermometers is very smallcompared to contact thermometers. They range between 1 msto 250 ms, strongly depending on the detector of the device.Because of thedetector theresponse time is limited in thelowerrange. The electronics help to correct and adjust the responsetime according to the application ( e.g. averaging or maximumhold).

The interface supports the analysis of the measuring results.The following interfacesare available:- Analog outputs 0/4 - 20 mA and 0 - 1/10 V- Bus, CAN and DP interfaces- RS232, RS485, USB.

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Documents

Basics of Noncatact Temperature Measurement - Infrared