The Table of Emissivity on the INFRAPOINT Messtechnik GmbH website, posted in 2009 (No longer available online) had summary data for a wide variety of materials broken down into three distinct spectral regions for the wavelength regions where the majority of infrared radiation thermometers and Infrared Thermal Imaging cameras operate.
First and second are tables that deal with the narrow spectral bands about 0.9 µm and 1.6 µm, the regions where many Silicon (Si) photovoltaic detectors (peak wavelength response: (0.9 µm) and both Germanium (Ge) and Indium Gallium Arsenide (InGaAs) (nominal wavelength region (0.7 – 1.6 µm) are used.
The third table cover the 8 – 14 µm waveband where most “low” (near ambient) temperature IR thermometers and thermal imaging sensors operate.
It has been reproduced here below in the spirit of Internet openness from our archives. We hope there is no problem in doing so and if any heir or assigns of INFRAPOINT Messtechnik GmbH wishes to keep this information secret, obviously against the original intent of INFRAPOINT, please contact us according to our webpage contact information.
|Table of emissivity|
|The emissivity ? (radiant emittance factor) is the relationship of the radiated intensity of a body to the intensity of a blackbody of the same temperature.
It is the most important factor, in order to determine of an item exactly.
If you want to measure the surface temperature with an infrared thermometer the emissivity must be known and correct adjusted
8 – 14 µm
|Aluminium, bright||0.05 – 0.25||0.05 – 0.25||Asphalt||0.95|
|Aluminium, anodized||0.2 – 0.4||0.1 – 0.4||Concrete||0.95|
|Chrom, bright||0.28 – 0.32||0.25 – 0.3||Gypsum||0.85 – 0.95|
|Iron, oxidised||0.4 – 0.8||0.5 – 0.9||Graphite||0.75 – 0.92|
|Iron, not oxidised||0.35||0.1 – 0.3||Glass*, pane||0.80|
|Gold, bright||0.02||0.02||Rubber||0.85 – 0.95|
|Copper, bright||0.06 – 0.20||0.06 – 0.20||Wood, natural||0.8 – 0.95|
|Copper, oxidised||0.5 – 0.8||0.7 – 0.85||Chalk||0.98|
|Magnesium||0.03 – 0.8||0.05 – 0.3||Ceramics||0.85 – 0.95|
|Brass, bright||0.8 – 0.95||0.01 – 0.05||Plastics||0.85 – 0.95|
|Brass, oxidised||0.65 – 0.75||0.65 – 0.75||Masonry||0.85 – 0.95|
|Nickel, oxidised||0.8 – 0.9||0.4 – 0.7||Human skin||0.98|
|Platinum, black||–||0,95||Oil paints||0.85 – 0.95|
|Silver||0.02||0.02||Paper||0.85 – 0.95|
|Steel, melted||0.30||0.20 – 0.25||Porcelain||0.85 – 0.95|
|Steel, oxidised||0.8 – 0.9||0.8 – 0.9||Quartz||0.8|
|Steel, bright||0.40 – 0.45||0.30 – 0.4||Carbon black||0.95|
|Titanium, bright||0.5 – 0.75||0.3 – 0.5||Chamotte||0.85 – 0.95|
|Titanium, oxidised||–||0.6 – 0.8||Textile, Drapery||0.85 – 0.95|
|Zinc, bright||0.6||0.4 – 0.6||Tone||0.95|
|Tin||0.25||0.1 – 0.3||Cement||0.9|
|* The emissivity of glass (0.95 – 0.97 µm) is in the range of 4.5 – 7 µm particularly high.
Glass has there an absorption band (spectral range, where materials absorb radiation).
To measure glass surface temperatures, the best wavelength is at 5.14 µm, because
the measurement at this range is not affected by absorption bands such as carbon or hydrogen.
Spectral emissivity of skin and pericardium by J Steketee 1973 Phys. Med. Biol. 18 686-694 doi: 10.1088/0031-9155/18/5/307 Help
J Steketee, Department of Biological and Medical Physics, Erasmus University, Rotterdam, The Netherlands
A monochromator was modified to measure the emissivity, ?(?), of living tissue in the infrared region between 1 and 14 ?m. The infrared radiation from the tissue was compared with blackbody radiation and in this way ?(?) has been determined for white skin, black skin, burnt skin and pericardium.
A compensating skin thermometer was constructed to measure the temperature of the surface of the tissue. The temperature difference before and after contact between a gold ring and the surface was made as small as possible (0.05 K). A reference radiator with the same spectral radiance (experimentally determined) mas used in compensating for the environment.
It appeared that ?(?) for skin is independent of the wavelength and equal to 0.98+-0.01. These results contradict those of Elam, Goodwin and Lloyd Williams, but are in good agreement with those of Hardy and Watmough and Oliver.
In addition there was no difference between ?(?) for normal skin and burnt skin. Epicardium values were found to lie between 0.83 (fresh heart) and 0.90 (after 7 h and after 9 d).
Print publication: Issue 5 (September 1973)
PDF (504 KB)
Reference Title:Non-contact skin emissivity: measurement from reflectance using step change in ambient radiation temperature Citation: T Togawa 1989 Clin. Phys. Physiol. Meas. 10 39-48 doi: 10.1088/0143-0815/10/1/004
Article by T Togawa of Inst. for Med. & Dental Eng., Tokyo Med. & Dental Univ., Japan
A method of estimating skin emissivity based on reflectance measurement upon transient stepwise change in the ambient radiation temperature was proposed. To effect this change, two shades at different temperatures were switched mechanically, and the change in radiation from the skin surface was recorded through an aperture for each shade by a high-resolution, fast-response radiometer having a sensitivity the 8-14 mu m range. Measurements were made on the forehead, forearm, palm and back of the hand in 10 male and 10 female subjects. No significant differences in emissivity were observed among sites and between sexes. The overall average of the skin emissivity obtained was 0.971+or-0.005 (SD). This result is inconsistent with most reported skin emissivity values. However, as the former studies had many inherent inadequacies, both theoretical and experimental, it is considered that most of these reported skin emissivities are unacceptable. The method proposed in the study has the following advantages: (1) relative calibration between instruments in unnecessary, (2) noncontact measurement can be achieved, and (3) each measurement can be made within one minute.
Available for purchase as a PDF (652 KB) downloadable document from the IOP website in the UK.
Temporal variations in the apparent emissivity of various materials
Author: Salvaggio, C.; Miller, D.P.
Author URL: www.cis.rit.edu/~cnspci/publications/5425-29.pdf
Spectral emissivity measurements gathered in the longwave infrared region of the spectrum during a recent airborne hyperspectral data collection experiment indicated that the spectral emissivity of certain organic polymers changed by as much as 10% throughout the day. Inorganic and many other organic materials that were measured at the same time during this experiment showed no change. As this was an unexpected event, a subsequent experiment was designed to make emissivity measurements of several organic and inorganic materials over a 24-hour period/diurnal cycle. The results from this experiment confirmed that certain materials showed a significant spectral emissivity variation over this period. This paper will discuss some possible explanations for this variation and emphasize the significance and implications of this fact on the integrity of spectral emissivity measurements and spectral libraries being constructed in this wavelength region.
Sensor Data Exploitation and Target Recognition, Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery X, Proceedings of the SPIE, Vol. 5425, Orlando, FL, April 2004
Portable Fourier transform infrared spectroradiometer for field measurements of radiance & emissivity
By Andrew R. Korb, Peter Dybwad, Winthrop Wadsworth, and John W. Salisbury
A hand-held, battery-powered Fourier transform infrared spectroradiometer weighing 12.5 kg has been developed for the field measurement of spectral radiance from the Earth’s surface and atmosphere in the 3–5-µm and 8–14-µm atmospheric windows, with a 6-cm21 spectral resolution. Other versions of this instrument measure spectral radiance between 0.4 and 20 µm, using different optical materials and detectors, with maximum spectral resolutions of 1 cm21. The instrument tested here has a measured noise-equivalent delta T of 0.01 °C, and it measures surface emissivities, in the ?eld, with an accuracy of 0.02 or better in the 8–14-µm window 1depending on atmospheric conditions2, and within 0.04 in accessible regions of the 3–5-µm window. The unique, patented design of the interferometer has permitted operation in weather ranging from 0 to 45 °C and 0 to 100% relative humidity, and in vibration-intensive environments such as moving helicopters. The instrument has made field measurements of radiance and emissivity for 3 yr without loss of optical alignment. We describe the design of the instrument and discuss methods used to calibrate spectral radiance and calculate spectral emissivity from radiance measurements. Examples of emissivity spectra are shown for both the 3–5-µm and 8–14-µm atmospheric windows.
Key words: Fourier transform infrared spectroradiometer, portable spectrometer, infrared radiance
measurement, radiometric calibration, spectral emissivity calculation.
Reference: Korb, A.R., P. Dybwad, W. Wadsworth, and J.W. Salisbury, 1996, Portable Fourier Transform Infrared Spectrometer for Field Measurements of Radiance and Emissivity, Applied Optics, v.35, p.1679-1692. http://www.dpinstruments.com/papers/applied_optics_update.pdf
Copyright 1996 Optical Society of America