SpectralEmissivity & Emittance

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Improving Temperature Measurement of Low Emissivity Targets

Helpful Tips for Users From FLIR

fliratspr118-imageMeer, Belgium — FLIR Systems has published a new technical note that investigates and describes how to use low-cost materials to increase target emissivity to enable accurate measurement using a thermal imaging camera.

Clean, unoxidized, bare metal surfaces such as are found in many R&D applications have low emissivity. Consequently they are difficult to analyse with a thermal imaging camera.

To get good accurate temperature measurements there is a consequent need to increase the emissivity of these problematic targets.

The technical note provides an informative introduction to emissivity and how a target’s emissivity, reflectance and thermal conductivity values are highly dependent on material properties.Read More

What the Heck is (Spectral) Emissivity?

Part One of Two from the mind of FLIR
It health partners pharmacies starts:

Fill two soda cans with hot water and wrap one with scotch tape. Which one will radiate more heat?

You might be surprised at the answer

(It has all to do with Spectral Emissivity, although this video continues the illusion that it’s really simple “Emissivity” at work! The concept of Emissivity is simple and easy to grasp as the video shows. The understanding is a bit more difficult and begins when one realizes that it is really Spectral Emissivity.)

But looking beyond that technical fine point, the video illustrates two other things:Read More

Spectral emissivity from 2 micrometers to 15 micrometers

Measurement of spectral emissivity from 2 micrometers to 15 micrometers
Charles D. Reid and E. D. McAlister
JOSA, Vol. 49, Issue 1, pp. 78- (1959)

C. D. Reid and E. D. McAlister, “Measurement of spectral emissivity from 2 micrometers to 15 micrometers,” J. Opt. Soc. Am. 49, 78- (1959)

ET10 Reflectometer Measures Emissivity

San Diego CA, USA –Surface Optics’ ET10 measures emissivity values in two most commonly used spectral regions, 3 to 5 and 8 to 12 microns.

Its main application is to produce emissivity values for the infrared cameras.

Advanced IR cameras require the input of an emissivity value for accurate temperature calculations. The emissivity values obtained from tables can be far from real leading to large temperature uncertainties.

The ET10 can be used in the lab or in the field and on small or large objects. With the ET10 one can measure emissivity of any surface in just a few seconds.

Read More

Spectral and Total Emissivity Measurement Services at Near Ambient Temperatures

The National Physical Laboratory in The UK offers a title=”Emissivity Measurement Service -PDF Downloadable Brochure” target=”_blank”>spectral emissivity measurment service (downloadable brochure – PDF 284kb) through its Infrared Optical Spectroscopy group to measure the spectral emissivity as needed by customers.

They also offer related calibration measurement services on their webpage as stated below:

Optical Properties of Materials Measurement Service offers calibrations in the areas of Spectrophotmetry (reflectance and transmittance measurements, colorimetry, measurement of appearance) and Infrared Spectrometric Measurements (reflectance and transmittance measurement)

On another webpage they repeat much of what’s in the downloadable document above and provide both equations and an informative sketch to illustrate the various measurement parameters involved.

Additionally, they provide a list of related reference documents that support the technologies involved in the services. These are quoted below:

“CLARKE, F.J.J. Measurement of the radiometric properties of materials for building and aerospace applications. Proc. Soc. Photo-Opt. Instrum. Eng., 1980, 234, 40-47.

CLARKE, F J J, and LARKIN, J A. Measurement of total reflectance, transmittance and emissivity over the thermal IR spectrum. Infrared Physics, 1985, 25, 359-367.

CLARKE, F J J, and LARKIN, J A. Emissivity determined from hemispherical reflectance and transmittance throughout the thermal infrared spectrum. High Temp. – High Press., 1985, 17, 89-96.

CLARKE, F J J and LARKIN, J A. Improved techniques for the NPL hemispherical reflectometer. Proc. Soc. Photo-Opt. Instrum. Eng., 1988, 917, 7-14.”