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Displaying 1 - 25 of 351

QUASAR-QUAsi-Stationary Absolute Radiance Mission

July 22, 2022
Author(s)
Eliad Peretz, Peter Plavchan, Piotr Pachowicz, Jamie Tayar, Gerard van Belle, Greg Aldering, Angelle Tanner, Justin Albert, Daniel Huber, Leonard Hanssen, Brian Alberding, Joseph P. Rice, Steven West, John Mather, Allison Youngblood, Tabetha Boyajian, Brian Stalder, Jonathan Gagne, Susana Deustua, Kayla Carmical, Andrew Lewis
This paper describes the scientific and developmental aspects behind the QUAsi-Stationary Absolute Radiance (QUASAR) mission study. The scientific motivation on which the mission is built is established, including the absolute flux calibration of standard

A pyroelectric detector-based method for low uncertainty spectral irradiance and radiance responsivity calibrations in the infrared using tunable lasers

April 4, 2022
Author(s)
Brian Alberding, John Woodward, Ping-Shine Shaw, Leonard Hanssen, Catherine Cooksey, Joseph P. Rice
The standard uncertainty of detector-based radiance and irradiance responsivity calibrations in the short-wave infrared (SWIR) traditionally has been limited to around 1 % or higher by the low spatial uniformity of detectors used to transfer the scale from

Design and Evaluation of Large Aperture Gallium Fixed Point Blackbody

October 12, 2021
Author(s)
V B. Khromchenko, Sergey Mekhontsev, Leonard Hanssen
To complement existing water bath blackbodies which are now serving as NIST primary standard sources in the temperature range from 15 C to 75 C, a gallium fixed point blackbody has been recently built. The main objectives of the project included creating

Measurement Uncertainty of Surface Temperature Distributions for Laser Powder Bed Fusion Processes

August 10, 2021
Author(s)
David Deisenroth, Sergey Mekhontsev, Brandon Lane, Leonard M. Hanssen, Ivan Zhirnov, Vladimir Khromchenko, Steven Grantham, Daniel Cardenas-Garcia, Alkan Donmez
This paper describes advances in measuring the characteristic spatial distribution of surface temperature and emissivity during laser-metal interaction under conditions relevant for laser powder bed fusion (LPBF) additive manufacturing processes. Detailed

Methods for Quantitative Infrared Directional-Hemispherical and Diffuse Reflectance Measurements Using a Fourier Transform Spectrometer and a Commercial Integrating Sphere

January 20, 2018
Author(s)
Leonard M. Hanssen, Thomas A. Blake, TImothy J. Johnson, Russell G. Tonkyn, Brenda M. Forland, Tanya L. Myers, Carolyn S. Brauer, Yin-Fong Su, Bruce E. Bernacki
Infrared integrating sphere measurements of solid samples are important in providing reference data for contact, standoff and remote sensing applications. At the Pacific Northwest National Laboratory (PNNL) we have developed protocols to measure both the