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Search Publications by

Benjamin K. Tsai (Fed)

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Displaying 1 - 25 of 106

Recent research and development in photometry at NIST

April 22, 2021
Yuqin Zong, Maria Nadal, Benjamin K. Tsai, C Cameron Miller
Many developments were made in recent years in photometry at NIST for reducing measurement uncertainties, increasing calibration efficiencies, and adding measurement capabilities. The 40 years old photometry laboratory has been renovated. The new

Reflectance data set and variability study for human skin reflectance

July 1, 2019
Catherine C. Cooksey, David W. Allen, Benjamin K. Tsai
The optical properties of human skin have been of interest to researchers for some time. Their interest is based on a need to know for a variety of different applications, which range from spectral imaging for automated or stand-off detection, non-invasive

Exposure Study on the Aging of PTFE and Ceramic Diffusers

February 6, 2019
Benjamin K. Tsai, Catherine C. Cooksey, David W. Allen, Christopher C. White, Walter E. Byrd, Deborah S. Jacobs
This paper describes efforts to quantify the effects of aging in the ultraviolet (UV) on polytetrafluoroethylene (PTFE) and ceramic samples. Long term UV aging may significantly alter the reflectance factor and cause an error in the calibration of

NIST Measurement Services: Photometric Calibrations

July 10, 2018
Carl C. Miller, Maria E. Nadal, Benjamin K. Tsai, Yuqin Zong
The National Institute of Standards and Technology provides calibration services for submitted artifacts for luminous intensity, illuminance, color temperature, total luminous flux, luminous exposure and luminance. Additionally, the National Institute of

Reference Data Set of Human Skin Reflectance

June 7, 2017
Catherine C. Cooksey, David W. Allen, Benjamin K. Tsai
This data set contains 100 reference reflectance spectra of human skin, spanning the wavelength region from 250 nm to 2500 nm. The spectra were acquired with a commercial spectrophotometer and are directly traceable to the national scale for directional


March 31, 2016
Carl C. Miller, Yoshihiro Ohno, Maria E. Nadal, Benjamin K. Tsai, Yuqin Zong
The National Institute of Standards and Technology (NIST) began to offer proficiency testing for Solid-State Lighting (SSL) products through a Measurement Assurance Program (MAP) in 2010. This article communicates the results of the first version of the

Spectral reflectance variability of skin and attributing factors

May 21, 2015
Catherine C. Cooksey, Benjamin K. Tsai, David W. Allen
Knowledge of the spectral reflectance signature of human skin over a wide spectral range will help advance the development of sensing systems for many applications, ranging from medical treatment to security technology. A critical component of the

Preface and Introduction

July 1, 2014
Thomas A. Germer, Joanne C. Zwinkels, Benjamin K. Tsai
This constitutes the front matter (preface and introductory chapter) to the book, "Spectrophotometry: Accurate Measurements of the Optical Properties of Materials," The introduction presents a short history of spectrophotometry. A very brief description of

Theoretical Concepts in Spectrophotometric Measurements

July 1, 2014
Thomas A. Germer, Joanne C. Zwinkels, Benjamin K. Tsai
This chapter will describe some of the theoretical concepts of obtaining optical properties from spectrophotometric measurements. The optical properties of interest can be the spectrophotometric quantities themselves or the calculated optical constants

NIST Measurement Services: Regular Spectral Transmittance

March 10, 2011
David W. Allen, Edward A. Early, Benjamin K. Tsai, Catherine C. Cooksey
This document describes measurement services, instrumentation, and measurement techniques for regular spectral transmittance over the spectral range from 250 nm to 2500 nm at the National Institute of Standards and Technology. Section 2 explains the basic

Temperature Fundamentals

December 29, 2009
Benjamin K. Tsai, Graham Machin
In this chapter the basic principles of temperature, its definition and measurement are given. Beginning with a brief outline of the fundamental principles, the reader is introduced to the concept of thermodynamic temperature and some of the primary means

The Extension of the NIST BRDF Scale from 1100 nm to 2500 nm

August 21, 2009
Howard W. Yoon, David W. Allen, George P. Eppeldauer, Benjamin K. Tsai
Measurements of bi-directional reflectance factor for diffuse reflectance from 1100 nm to 2500 nm using extended-range indium gallium arsenide (exInGaAs) detectors in the NIST Spectral Tri-function Automated Reference Reflectometer (STARR) facility are

A Summary of Lightpipe Radiation Thermometry Research at NIST

April 1, 2006
Benjamin K. Tsai
During the last ten years, research in lightpipe radiation thermometry has significantly reduced the uncertainties for temperature measurements in semiconductor processing. The National Institute of Standards and Technology (NIST) has improved the

Infrared Emittance Measurements at NIST

October 5, 2005
Leonard M. Hanssen, Benjamin K. Tsai, Sergey Mekhontsev
A new capability for the measurement of the temperature-dependent emittance of specular samples in the near infrared spectral region has been developed in NIST s Infrared Spectrophotometry Laboratory to provide emittance measurements and standards for a