Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Broadband Emissivity Calibration of Highly Reflective Samples at Cryogenic Temperatures



Solomon I. Woods, Timothy M. Jung, Greg Ly, Simon G. Kaplan, Jie Yu


We have developed a technique for calibrating the broadband optical emissivity of high reflectivity samples at cryogenic temperatures. This measurement method employs a primary standard optical detector with high absorptance from visible wavelengths to beyond 200 µm, and background subtraction and quantification allow determination of the emissivity with total absolute uncertainty between 0.0001 and 0.001 for temperatures from 80 K to 300 K. Using the irradiance data at the detector, precise measurements of the experimental geometry and diffraction calculations, the optical power emitted by the sample can be determined. Contact thermometry measurements for the sample can then be used to find its emissivity. The emissivity calibration technique is demonstrated for large plate samples made from polished stainless steel and is also extended to calculate the separate emissivities of multiple distinct regions on a more complex sample assembly.


emissivity, low-temperature radiance, radiation thermometry, infrared calibration, absolute cryogenic radiometer, ACR, ITER


Woods, S. , Jung, T. , Ly, G. , Kaplan, S. and Yu, J. (2012), Broadband Emissivity Calibration of Highly Reflective Samples at Cryogenic Temperatures, Metrologia, [online], (Accessed April 20, 2024)
Created October 15, 2012, Updated February 19, 2017