Archive for Solids & Liquids

Reflectivity of Mineral Powders

From the Website of Ocean Optics, an applications note for their Jaz Spectrometer

 Figure-3-Experiment-Setup.jpgIt begins:

“Reflectance spectroscopy is a versatile technique than can be used to identify and characterize a range of powdered samples including mineral powders, grains in lunar samples, mining samples, natural deposits, soils and sediment core samples. In this application note, reflectance spectroscopy is used to characterize mineral powder samples.

The Jaz spectrometer was used to acquire reflectance spectra for pure samples and powder mixtures to assess the power of reflectance spectroscopy to characterize mineral powder samples.”

Figure-3-Experiment-Setup.jpg from the Ocean Optics Blog

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Publications of Robert O. Knuteson

Reference online: http://library.ssec.wisc.edu/publications/resultOnly.php?authorText=Knuteson,%20Robert%20O.&numOfRecs=25&currPage=1.

Sample Entries of the 38 records online at the University of Wisconsin Library:

1. Seemann, Suzanne W.; Borbas, Eva E.; Knuteson, Robert O.; Stephenson, Gordon R. and Huang, Hung-Lung. Development of a global infrared land surface emissivity database for application to clear sky sounding retrievals from multispectral satellite radiance measurements. Reprint # Journal of Applied Meteorology and Climatology, Volume 47, Issue 1, 2008, pp.108-123. Call Number: Reprint # 5663

2. Tobin, David C.; Antonelli, Paolo; Revercomb, Henry E.; Dutcher, Steven; Turner, David D.; Taylor, Joe K.; Knuteson, Robert O. and Vinson, Kenneth. Hyperspectral data noise characterization using principle component analysis: Application to the atmospheric infrared sounder. Reprint # Journal of Applied Remote Sensing, Volume 1, 2007, Doi:10.1117/1.2757707. Call Number: Reprint # 5392…

Emissivity of Human Skin in the Waveband between 2 & 6 micrometers

From a Nature Article of the same title:

By DAVID J. WATMOUGH & R. OLIVER, Department of Radiation Physics, Churchill Hospital, Oxford.
Citation: Nature 219, 622 – 624 (10 August 1968); doi:10.1038

Abstract:

The emissivity of human skin epsilon(lambda) in the range 2micro to 6micro has recently assumed considerable importance because of the increasing medical use of infrared scanners to measure skin temperature (t). Several commercially available scanners utilize indium antimonide detectors which are sensitive in the range 2micro to 5.4micro . Such machines measure the energy (Q) Bactrim radiated by the skin and, being calibrated against a standard black body, changes in Q are represented as variations in skin temperature. Dreyfus1 has shown that Q is related to t by an equation of the form, where k is a constant, and where the index n depends on lambda as lambdamax being the wavelength corresponding to the maximum in the emission curve. The importance of variations in emissivity can be seen by differentiating equation (1) for constant Q. We obtain which simplifies to give for Deltat For a skin temperature of 27° C (t=300° K), n is about 12.5. It follows from equation (2) that if epsilon(lambda) were to vary by as much as 5 per cent over the skin surface, this would be interpreted by the scanner as a temperature variation of about 1° C. A fairly accurate knowledge of epsilon(lambda) is thus necessary, for hot spots with temperature elevations of only 2° C are considered to be of clinical significance.

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Determination of the Infrared Emissivity with Multi-spectral Thermal Infrared Data from Space

A 2004 Amercian Geophysical Union Conference Presentation by:

Schmugge, T (schmugge@hydrolab.arsusda.gov) , USDA/ARS Hydrology and Remote Sensing Lab, Bldg. 007 – BARC West, Beltsville, MD 20705 United States
Ogawa, K (k-ogawa@dsg.hitachi.co.jp) , Hitachi Ltd., 4-6 Kanda-Surugadai Chiyoda- Ku,, Tokyo, 101-8010 Japan
Ogawa, K (k-ogawa@dsg.hitachi.co.jp) , Faculty of Engineering,University of Tokyo, University of Tokyo, Tokyo, 113-0033 Japan
Rokugawa, S (rokugawa@gpl.t.u-tokyo.ac.jp) , Faculty of Engineering,University of Tokyo, University of Tokyo, Tokyo, 113-0033 Japan » Read more..

Fluke Calibrator Video

Emissivity makes a temperature difference for infrared thermometers.

In the YouTube video below, Frank Liebman, an engineer with Fluke Corporation’s Hart Scientific Division demonstrates the impact that surface emissivity has on temperature measurement and temperature calibration using a modified Fluke blackbody calibrator and Fluke Thermal Imager.

We were surprised to see that no one commented on this video, despite an ending that leaves one hanging, at least us, with the obvious question: How do you do a radiometric calibration of a surface of unknown emissivity using a Fluke Blackbody Calibrator?

Do you have any ideas?