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Comparison of the radiation temperature scales of the PTB and the NPL in the temperature range from -57 °C to 50 °C.

Gutschwager, B*; Theocharous, E; Monte, C*; Adibekyan, A*; Reiniger, M*; Fox, N P; Hollandt, J* (2013) Comparison of the radiation temperature scales of the PTB and the NPL in the temperature range from -57 °C to 50 °C. Meas. Sci. Technol., 24 (6). 065002

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Blackbody sources at near-ambient-temperature are routinely used for the calibration of infrared instruments used in remote sensing and thermal imaging in terms of radiance and radiation temperature. The measured temperature of the blackbody and its calculated effective emissivity determine the radiance and radiation temperature of the blackbody according to Planck's law. The temperature measurement is generally accomplished with a contact thermometer which is calibrated in terms of the International Temperature Scale (ITS-90). The ammonia heat-pipe blackbody of the Physikalisch-Technische Bundesanstalt (PTB) in Germany is a primary source standard working in a wide spectral range with low uncertainties, i.e. less than 33 mK at 10 µm in a temperature range from -60 °C to 50 °C. A more direct method of absolute radiance measurement is the use of an absolutely calibrated radiometer. AMBER (Absolute Measurements of Blackbody Emitted Radiance) is an absolutely calibrated radiometer of the Optical Measurement Group of the National Physical Laboratory (NPL) in the UK which was specially designed to determine the radiance and hence the radiation temperature of near-ambient-temperature blackbodies. The traceability of AMBER to the SI is obtained directly through a primary detector standard, the cryogenic radiometer, when it is operating at shorter wavelengths where radiation detectors offering good long term stability exist. However, the detectors operating in the 8 µm to 12 µm wavelength range offer poor long term stability so when AMBER is used in this wavelength range, a gallium fixed point blackbody is used to verify the stability of the calibration of AMBER. This paper gives the results of a direct comparison of the ammonia heat-pipe blackbody with AMBER performed at the PTB

Item Type: Article
Subjects: Optical Radiation and Photonics
Optical Radiation and Photonics > Environment and Climate Change
Identification number/DOI: 10.1088/0957-0233/24/6/065002
Last Modified: 02 Feb 2018 13:14
URI: http://eprintspublications.npl.co.uk/id/eprint/5853

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