SpectralEmissivity & Emittance

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IR spectral characterization of customer blackbody sources:

“First calibration results”

A paper by S. Mekhontsev, M. Noorma, A. Prokhorov, and L. Hanssen from NIST in the USA, Presented at Thermosense XXVIII, ed. by Jonathan J. Miles, G. Raymond Peacock, and Kathryn M. Knettel, Proc. of SPIE 6205, 620503 (2006).

ABSTRACT:

We summarize recent progress in our infrared (IR) spectral radiance metrology effort. In support of customer blackbody characterization, a realization of the spectral radiance scale has been undertaken in the temperature range of 232 °C to 962 °C and spectral range of 2.5 µm to 20 µm. We discuss the scale realization process that includes the use of Sn, Zn, Al and Ag fixed-point blackbodies (BB), as well as the transfer of the spectral radiance scale to transfer standard BBs based on water, Cs and Na heat pipes. Further we discuss the procedures for customer source calibration with several examples of the spectral radiance and emissivity measurements of secondary standard BB sources. For one of the BBs, a substantial deviation of emissivity values from the manufacturer specifications was found. Further plans include expansion of the adopted methodology for temperatures down to 15°C and building a dedicated facility for spectral characterization of IR radiation sources.

It presently can be downloaded from the NIST website in PDF format by CLICKING HERE

A Temperature and Emissivity Separation Algorithm…

A Temperature and Emissivity Separation Algorithm for Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Images

by: Alan Gillespie, Shuichi Rokugawa, Tsuneo Matsunaga, J. Steven Cothern, Simon Hook, and Anne Kahle
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Manuscript received October 31, 1997. This work was a collaborative effort of the U.S. and Japanese EOS/ASTER instrument teams, sponsored by the NASA EOS Project and ERSDAC.

A. Gillespie and J.S. Cothern are with the Department of Geological Sciences, University of Washington, Seattle, Washington 98195-1310, USA.

S. Rokugawa is with The University of Tokyo, Faculty of Engineering, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, JAPAN.

T. Matsunaga is with the Geological Survey of Japan, 1-1-3 Higashi, Tsukuba, Ibaraki 305, JAPAN.

S. Hook and A. Kahle are with the Jet Propulsion Laboratory 183-501, Pasadena, California 91109, USA

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Abstract:
The ASTER scanner on NASA’s EOS-AM1 satellite (launch: June, 1998) will collect five channels of TIR data with an NE DT of <0.3 K to estimate surface temperatures and emissivity spectra, especially over land, where emissivities are not known in advance. Temperature/emissivity separation (TES) is difficult because there are five measurements but six unknowns. Various approaches have been used to constrain the extra degree of freedom. ASTER’s TES algorithm hybridizes three established algorithms, first estimating the normalized emissivities, and then calculating emissivity band ratios. An empirical relationship predicts the minimum emissivity from the spectral contrast of the ratioed values, permitting recovery of the emissivity spectrum. TES uses an iterative approach to remove reflected sky irradiance. Based on numerical simulation, TES should be able to recover temperatures within about 1.5K, and emissivities within about 0.015. Validation using airborne simulator images taken over playas and ponds in central Nevada demonstrates that, with proper atmospheric compensation, it is possible to meet the theoretical expectations. The main sources of uncertainty in the output temperature and emissivity images are the empirical relationship between emissivity values and spectral contrast, compensation for reflected sky irradiance, and ASTER’s precision, calibration, and atmospheric correction.

Spectral emissivity & brightness temperatures of platinum

Spectral emissivity and the relation of true temperatures and brightness temperatures of platinum
Robert E. Stephens
JOSA, Vol. 29, Issue 4, pp. 158-161 (1939)

Citation
R. E. Stephens, “Spectral emissivity and the relation of true temperatures and brightness temperatures of platinum,” J. Opt. Soc. Am. 29, 158-161 (1939)