Simple radiometric method for measuring the thermal broadband emissivity of material samples.
Whereas thermal emissivities, together with surface temperatures, are decisive factors with regard to object signatures observed in infrared imagery, it is unfortunate that emissivity measurements are not easily made. Known methods may require specially built or expensive equipment or may be selective with respect to the types of material that can be investigated. No internationally agreed-on method is available. From basic physical principles, I outline a radiometric outdoor technique by which essentially all types of material can be measured by utilizing the difference between ground and sky temperatures. The accuracy of this simple method appears to compare favorably with that of other methods that cover the 8-14-microm wave band.
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