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SSE- and Noise-Optimized InGaAs Radiation Thermometer

Published

Author(s)

Howard W. Yoon, Charles E. Gibson, V B. Khromchenko, George P. Eppeldauer

Abstract

For the measurements of radiance temperatures in the range from 150 ?C to 1000 ?C, low uncertainties in the temperature measurements can be achieved by using near-infrared InGaAs radiation thermometers. We describe the design and construction of the NIST near-infrared radiation thermometer (NIRT) which is optimized for low size-of-source effect and noise-equivalent temperatures. The NIRT utilizes a 50 mm diameter achromatic objective lens with low scatter that images a 4.5 mm diameter spot at a distance of 50 cm away from the objective in an on-axis design. A Lyot stop is implemented in the design with the aperture stop placed after the field stop resulting in a collection f/12. A 3 mm diameter InGaAs detector is cooled to 85 ?C using a 4-stage thermoelectric cooler to obtain high-shunt resistance for linear, low-noise operation at high transimpedance amplifier gains. For thermal and structural stability, the optical components are placed on four, 15 mm diameter graphite-epoxy rods making the optical throughput stable. Optical ray tracing with a commercial program was used to determine the Strehl ratio and other imaging parameters. We discuss a possible approach for a detector-based temperature scale in this range which could result in 10 mK (k = 2) thermodynamic temperature uncertainties at the In-point.
Citation
International Journal of Thermophysics

Keywords

ITS-90, near-infrared radiation thermometer, noise-equivalent temperature difference, radiance temperature, size-of-source effect

Citation

Yoon, H. , Gibson, C. , Khromchenko, V. and Eppeldauer, G. (2008), SSE- and Noise-Optimized InGaAs Radiation Thermometer, International Journal of Thermophysics (Accessed June 21, 2024)

Issues

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Created October 16, 2008