A non-contact technique providing improved accuracy in area measurements of radiometric apertures

Hartmann, Jürgen; Fischer, Joachim; Seidel, Joachim

doi:10.1088/0026-1394/37/5/67

Cited by 22 publications

(19 citation statements)

References 8 publications

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“…For the calibration at the spectral comparator facility, the sensitive area of the transfer standards for spectral power responsivity is limited with a precision, diamond-turned aperture with a nominal diameter of about 3 mm. The diameter of the aperture has been separately measured with the method outlined in [11]. By this means, these transfer standards are transferred into transfer standards of spectral irradiance responsivity.…”

Section: Calibration Of the Spectral Irradiance Responsivitymentioning

confidence: 99%

Infrared Filter Radiometers for Thermodynamic Temperature Determination below 660 °C

et al. 2008

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At the Physikalisch-Technische Bundesanstalt (PTB), absolutelycalibrated filter radiometers based on silicon photodiodes are routinely used for thermodynamic temperature determinations of blackbodies in the range from the zinc fixed point (FP) (419 • C) up to 3,000 • C. To extend the temperature range down to the tin FP (232 • C), we have designed two new filter radiometers based on indium gallium arsenide (InGaAs) photodiodes with center wavelengths at 1,300 nm and 1,550 nm. For the absolute calibration of the spectral irradiance responsivity of the new InGaAs filter radiometers, the spectral responsivity measurement in the near-infrared (NIR) spectral range has been significantly improved. With a newly developed tuneable laser and monochromator-based cryogenic radiometer facility, the relative standard uncertainty of the NIR spectral responsivity has been reduced from 0.17 % to about 0.03 %. By using the calibrated InGaAs filter radiometer in conjunction with the large-area double sodium heat pipe of the PTB, the first results for the difference between the thermodynamic temperature T and the ITS-90 temperature T 90 in the temperature range from the zinc FP up to the aluminum FP (660 • C) are presented. The values for T -T 90 determined with the new InGaAs filter radiometers are consistent within their relative standard uncertainty of about 30 mK at 419 • C to about 60 mK at 660 • C.

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Section: Calibration Of the Spectral Irradiance Responsivitymentioning

confidence: 99%

Infrared Filter Radiometers for Thermodynamic Temperature Determination below 660 °C

et al. 2008

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“…To prevent inter-reflections and to accurately define the position of the aperture plane, the aperture edges, the cylindrical part of the aperture opening (the so-called land) should be steepsided and as thin as possible, with a typical thickness of 10 µm to 20 µm [11]. Due to these fragile edges, predominantly non-contact measuring techniques have been used to measure the area of these apertures [11][12][13]. Recently, an international comparison of different methods for measuring aperture areas has been evaluated, showing that the agreement of the different methods depends critically on the quality of the apertures [14].…”

Section: Determination Of the Geometry Factor Gmentioning

confidence: 99%

Absolute Radiometry for the MeP-K: The Irradiance Measurement Method

et al. 2011

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The "Mise en pratique for the definition of the kelvin" (MeP-K) as a guide for the realization of the kelvin is presently revised to incorporate the temperature scales in current use as the best formal approximations of the thermodynamic temperature and, additionally, direct methods of thermodynamic temperature measurement. Within the MeP-K, the CCT WG 5 "Radiation Thermometry" develops a document to facilitate the implementation of thermodynamic temperature measurements at temperatures above the silver fixed point (961.78 • C). Three thermodynamic temperature measurement methods, all relying on absolute spectral-band radiometry, are proposed. To make these techniques more accessible for the broader thermometry community, each of these methods is described in detail in an accompanying paper to the MeP-K. These descriptions shall not be understood as a restriction to other possible radiometric methods of thermodynamic temperature measurement. One of the methods of radiometric temperature measurement above the silver point is the absolute measurement of irradiance in a well-defined spectral band. This is a straightforward method, which relies on filter radiometers with known spectral irradiance responsivity and a well-defined observation geometry, without any imaging technique. It has been developed for thermodynamic temperature measurements of precision blackbodies as primary standards for radiometry and thermometry and for the investigation of the uncertainty of the ITS-90 as an approximation of the thermodynamic temperature over a period of nearly 20 years at PTB. The article describes the design of the applied filter radiometers, their calibration chain, and their long-term stability. Additionally, the

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“…This can be achieved using a coordinate measuring machine, for apertures with a sufficiently large land for contact, and with optical techniques (optical coordinate measurement or radiometric techniques, e.g., [10]) for thin film apertures. See also Sect.…”

Section: Geometrical Setupmentioning

confidence: 99%

Primary Radiometry for the Mise-en-Pratique for the Definition of the Kelvin: The Hybrid Method

et al. 2011

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A task group of CCT-WG5 (radiation thermometry) was established in May 2008 to write text for the mise-en-pratique for the definition of the kelvin (MeP-K) for high temperatures. This task group reviewed and gave summaries for the existing techniques for filter radiometry as a means of determining the absolute radiance, and hence the thermodynamic temperature of a blackbody source. Three approaches were described-the radiance method, which calibrates the radiation thermometer for radiance responsivity, the irradiance method, which calibrates a filter radiometer for irradiance responsivity and then measures the source through two apertures, and the hybrid method that introduces a lens to the irradiance method. In the "hybrid method" the radiation thermometer consists of a filter radiometer, a double aperture system, and a lens. The lens allows the instrument to view a small area blackbody source. The system is calibrated "in parts"-i.e., the filter radiometer is calibrated for irradiance responsivity, and the transmittance of the lens and the geometric factor are determined separately. The main drawbacks of this single lens instrument are its high size-of-source effect (∼0.2 %), and that this effect has to be determined in an "absolute" sense-relative to a theoretical infinite source. However, although the correction is large, with careful evaluation, the associated uncertainty can be made sufficiently small to measure the temperature of fixed-point cell transitions with low uncertainties. This article reviews the hybrid method and gives a comprehensive discussion of the associated uncertainty components.

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A non-contact technique providing improved accuracy in area measurements of radiometric apertures

Cited by 22 publications

References 8 publications

Infrared Filter Radiometers for Thermodynamic Temperature Determination below 660 °C

Infrared Filter Radiometers for Thermodynamic Temperature Determination below 660 °C

Absolute Radiometry for the MeP-K: The Irradiance Measurement Method

Primary Radiometry for the Mise-en-Pratique for the Definition of the Kelvin: The Hybrid Method

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