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Search Publications by: Yuqin Zong ()

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Displaying 1 - 25 of 50

Results of an Interlaboratory Study on the Working Curve in Vat Photopolymerization

March 18, 2024
Author(s)
Thomas Kolibaba, Jason Killgore, Benjamin Caplins, Callie Higgins, Uwe Arp, C Cameron Miller, Yuqin Zong
The working curve informs resin properties and print parameters for stereolithography, digital light processing, and other photopolymer additive manufacturing (PAM) technologies. First demonstrated in 1992, the working curve measurement of cure depth vs

Impact of fin aspect ratio on enhancement of external quantum efficiency in single AlGaN fin light-emitting diodes pixels

June 26, 2023
Author(s)
Babak Nikoobakht, Yuqin Zong, Okan Koksal, Amit Agrawal, Christopher B. Montgomery, Jacob Leach, Michael Shur
Previously, we showed within a sub-micron fin shape heterojunction, as current density increases, the non-radiative Auger recombination saturates mediated by the extension of the depletion region into the fin, resulting in a droop-free behavior. In this

Characterizing light engine uniformity and its influence on LCD-based vat photopolymerization printing

December 27, 2022
Author(s)
Benjamin Caplins, Callie Higgins, Thomas Kolibaba, Uwe Arp, C Cameron Miller, Dianne L. Poster, Clarence Zarobila, Yuqin Zong, Jason Killgore
Vat photopolymerization (VP) is a rapidly growing category of additive manufacturing. As VP methods mature the expectation is that the quality of printed parts will be highly reproducible. At present, detailed characterization of the light engines used in

NIST Traveling Tunable Laser Projector (TTLP) for UV-Blue Disinfection Dose Determinations

June 21, 2022
Author(s)
Thomas C. Larason, Steven Grantham, Clarence Zarobila, Yuqin Zong, C Cameron Miller, Michael Schuit, Brian Holland, Stewart Wood, Melissa Krause
As COVID-19 was overtaking the world in the spring of 2020, the National Institute of Standards and Technology began collaborating with the National Biodefense Analysis and Countermeasures Center to study the inactivation of SARS-CoV-2 to different UV and

Final report on the CCPR Key Comparison CCPR-K3.2014 Luminous Intensity

June 16, 2022
Author(s)
C Cameron Miller, Yuqin Zong, Arnold Gaertner, Eric Cote, Joaquin Campos, Gael Obein, Peter Blattner, Reto Scafer, Liu Hui, Jiang Xiaomei, Errol Atkinson, Erik Thorvaldson, Kenichi Kinoshita, Rheinhardt Sieberhagen, Irma Rabe, Teresa Goodman, Barry Scott, Armin Sperling, Detlef Lindner, Boris KHlevnoy, Evgeniy Ivashin
The metrological equivalence of national measurement standards in the field of photometry and radiometry is determined by a set of key comparisons chosen and organized by the Consultative Committee of Photometry and Radiometry (CCPR) of the Comité

CALIBRATION OF SPECTRORADIOMETERS USING TUNABLE LASERS

April 22, 2021
Author(s)
Yuqin Zong, Ping-Shine Shaw, Joseph Rice, C Cameron Miller
To shorten the long calibration chain when using the conventional source-based approach and therefore to reduce spectroradiometer's calibration uncertainty, we developed a detector-based approach to calibrate spectroradiometers directly against a transfer

Recent research and development in photometry at NIST

April 22, 2021
Author(s)
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

STANDARD LEDS WITH SUPERIOR LONG-TERM STABILITY

April 22, 2021
Author(s)
Yuqin Zong, Weiqiang Zhao, C Cameron Miller
A large-chip standard LED with superior long-term stability have been developed at NIST. The standard LED uses a large, specialty die rated for 50 W but is operated under 3 W to eliminate aging effect. The standard LED was seasoned for one year and

High-brightness lasing at submicrometer enabled by droop-free fin light-emitting diodes (LEDs)

August 14, 2020
Author(s)
Robin P. Hansen, Amit K. Agrawal, Michael Shur, Jerry Tersoff, Babak Nikoobakht, Yuqin Zong
"Efficiency droop," i.e., a decline in brightness of light-emitting diodes (LEDs) at high electrical currents, limits the performance of all commercial LEDs and has limited the output power of submicrometer LEDs and lasers to nanowatts. We present a fin p

Invited Article: Advances in Tunable Laser-based Radiometric Calibration Applications at the National Institute of Standards and Technology, USA

September 26, 2018
Author(s)
John T. Woodward IV, Ping-Shine Shaw, Howard Yoon, Yuqin Zong, Steven W. Brown, Keith R. Lykke
Recent developments at the National Institute of Standards and Technology's facility for Spectral Irradiance and Radiance responsivity Calibrations using Uniform Sources (SIRCUS) are presented. The facility is predicated on the use of broadly tunable

NIST Measurement Services: Photometric Calibrations

July 10, 2018
Author(s)
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

SOLID-STATE LIGHTING MEASUREMENT ASSURANCE PROGRAM SUMMARY WITH ANALYSIS OF METADATA

March 31, 2016
Author(s)
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

Proceedings of SPIE

March 4, 2015
Author(s)
Maritoni A. Litorja, Aaron A. Urbas, Yuqin Zong
The fluorescent light detected by a clinical imager is assumed to be proportional to the amount of fluorescent substance present in the sample. Unfortunately, there are many factors that can add or subtract to the light signal directly attributable to the

DEVELOPMENT OF 2 pi? TOTAL SPECTRAL RADIANT FLUX STANDARDS AT NIST

April 23, 2014
Author(s)
Yuqin Zong, Haiping Shen
We have developed a new, reflector lamp based 2 pi transfer standard for total spectral radiant flux (TSRF) scale in the spectral range from 360 nm to 1100 nm. Correlated colour temperature of the standard lamp is 3000 K. Spectral aging rate is ±0.3 % for

The distance dependences and spatial uniformities of spectral irradiance standard lamps

October 19, 2012
Author(s)
Howard W. Yoon, Gary D. Graham, Robert D. Saunders, Yuqin Zong, Eric L. Shirley
We describe the characterization of a group of NIST spectral irradiance lamps at longer distances and larger angles than are typically issued by NIST. The spectral irradiances from the FEL lamps were measured from 50 cm to 150 cm at 8 different distances

Development of a fully automated LED lifetime test system

September 21, 2012
Author(s)
Yuqin Zong, Jeff Hulett
A fully automated system for light-emitting diode (LED) lifetime test has been developed and is undergoing validation. This system uses a 1 m integrating sphere for both aging and optical measurements of 480 LEDs. It features six test zones, each of which

Stray light correction algorithm for multi-spectral hyperspectral spectrographs

June 1, 2012
Author(s)
Michael Feinholz, Stephanie J. Flora, Steven W. Brown, Yuqin Zong, Keith R. Lykke, Mark A. Yarbrough, B. Carol Johnson, D. K. Clark
An algorithm is developed to correct a multi-channel fiber-coupled spectrograph for stray or scattered light within the system. The efficacy of the algorithm is evaluated based on a series of validation measurements of sources with different spectral

Analysis of Uncertainties in Stray-Light Correction

December 1, 2010
Author(s)
Yuqin Zong
Measurement errors arising from stray light within a spectroradiometer are often the dominant source of uncertainty and are difficult to reduce. However, the stray-light errors can be corrected by using a stray-light correction matrix that is derived from