NIST Special Publication 250-43

NIST MEASUREMENT SERVICES:
Radiance Temperature Calibrations
Charles E. Gibson, Benjamin K. Tsai, and Albert C. Parr
Optical Technology Division
Physics Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899
December 1997


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This document describes the realization and dissemination of the International Temperature Scale of 1990 (ITS-90) above 700 °C at the National Institute of Standards and Technology (NIST). By using fundamental principles of blackbody physics, the ITS-90 scale is first fixed at the freezing point of gold (T₉₀ = 1064.18 °C) and is then extended to temperatures between 700 °C and 2700 °C by determining the ratio of the spectral radiance of a tungsten ribbon filament lamp to that of a gold fixed-point blackbody at a wavelength of 655.3 nm. A description of the facilities in the NIST Radiance Temperature Calibration Laboratory is given, along with a discussion of the wavelength calibration, size of source, and linearity issues. The use and calibration of radiance temperature standards are explained. Values of stability and uncertainties in the scale are reported. The expanded uncertainties (k = 2) at 800 °C and 2300 °C are 0.6 °C and 1.4 °C for ribbon filament lamps, 4 °C and 7 °C for disappearing filament optical pyrometers, and 2 °C and 3 °C for infrared radiation thermometers.

Contents

Cover/Table of Contents

1. Introduction

2. Measurement theory

3. Realization of the U.S. national scale of radiance temperature

3.1 1990 NIST scale of radiance temperature

3.2 Temperature standards

  3.2.1 Gold-point blackbody

  3.2.2 Tungsten ribbon filament lamps

  3.2.3 Working standard lamps

  3.2.4 Variable-temperature blackbody

3.3 NIST photoelectric pyrometer

  3.3.1 Measurement system

  3.3.2 Optical system

  3.3.3 Interference filters

  3.3.4 Detectors

  3.3.5 Linearity of response

  3.3.6 Wavelength calibration

  3.3.7 Size of source effect

3.4 Radiance temperature scale uncertainties

3.5 Quality control

4. Tungsten ribbon filament lamp calibrations

4.1 Lamp preparation

4.2 Lamp calibration

4.3 Lamp data analysis

4.4 Lamp calibration uncertainty

5. Disappearing filament optical pyrometer calibrations

5.1 Optical pyrometer preparation

5.2 Optical pyrometer calibration

5.3 Optical pyrometer data analysis

5.4 Optical pyrometer calibration uncertainty

6. Radiation thermometer calibrations

6.1 Radiation thermometer preparation

6.2 Radiation thermometer calibration

6.3 Radiation thermometer data analysis

6.4 Radiation thermometer calibration uncertainty

7. Modifications to the NIST photoelectric pyrometer

Acknowledgments

References

Appendix A: Ribbon filament lamp sample calibration report

Appendix B: Optical pyrometer sample calibration report

Appendix C: Radiation thermometer sample calibration report

Appendix D: Radiance temperature measurement services laboratory procedure manual

Appendix E: How to request radiance temperature calibration services

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