Towards high-accuracy primary spectral radiometry from 400 K to 1300 K.

Area of Science:

• Thermodynamics
• Radiometry
• Metrology

Background:

• The kelvin is undergoing redefinition, necessitating precise thermodynamic temperature measurements.
• Current methods rely on fixed-point blackbodies for the international temperature scale.
• Accurate measurement of Planck radiances across varying spectral shapes and radiance levels presents challenges.

Purpose of the Study:

• To design, construct, calibrate, and utilize a near-infrared thermodynamic radiation thermometer.
• To measure blackbody temperatures within the range of 400 K to 1300 K.
• To provide direct thermodynamic temperature measurements for the redefinition of the kelvin.

Main Methods:

• Development of a near-infrared thermodynamic radiation thermometer.
• Characterization of individual thermometer components.
• Radiometric calibration procedures for absolute primary thermometry.
• Utilizing the thermometer as a relative primary thermometer to assess residuals.

Main Results:

• Successful design and construction of the thermodynamic radiation thermometer.
• Demonstration of its use for measuring blackbody temperatures.
• Characterization of components and initial radiometric calibration steps.

Conclusions:

• The developed thermometer is suitable for direct thermodynamic temperature measurements.
• This work addresses the need for precise measurements supporting the kelvin redefinition.
• Further calibration is ongoing to establish it as an absolute primary thermometer.