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Search Publications by: Marla L. Dowell (Fed)

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Displaying 1 - 25 of 99

Advancing Measurement Science for Microelectronics: CHIPS R&D Metrology Program

February 13, 2024
Author(s)
Marla L. Dowell, Hannah Brown, Gretchen Greene, Paul D. Hale, Brian Hoskins, Sarah Hughes, Bob R. Keller, R Joseph Kline, June W. Lau, Jeff Shainline
The CHIPS and Science Act of 2022 called for NIST to "carry out a microelectronics research program to enable advances and breakthroughs....that will accelerate the underlying R&D for metrology of next-generation microelectronics and ensure the

Radio Spectrum Occupancy Measurements Amid COVID-19 Telework and Telehealth

October 14, 2022
Author(s)
Dan Kuester, Xifeng Lu, Dazhen Gu, Azizollah Kord, Jake Rezac, Katie Carson, Marla L. Dowell, Elizabeth Eyeson, Ari Feldman, Keith Forsyth, Vu Le, John Marts, Mike McNulty, Kyle Neubarth, Andre Rosete, Matthew Ryan, Maija Teraslina
During the COVID-19 pandemic, NIST began a targeted campaign of measurements of averaged power and occupancy rate in the radio spectrum. The purpose was to sample real environments to offer timely insights into data infrastructure where it might be

A Planar Hyperblack Absolute Radiometer

November 14, 2016
Author(s)
John H. Lehman, Michelle S. Stephens, Malcolm G. White, Andreas Steiger, Christian Monte, Joerg Hollandt, Ivan Ryger, Mathias Kehrt, Marla L. Dowell
The absolute responsivity of a planar radiometer fabricated from micromachined silicon and having carbon nanotubes as the absorber and thermistor was measured in the visible and far infrared (free-field terahertz) wavelength range by means of detector

Laser Welding of Dual-Phase Galvanized Sheet Steel

March 18, 2016
Author(s)
Stephanie L. Miller, Erik A. Pfeif, Andrei F. Kazakov, Esther Baumann, Marla L. Dowell
Laser welding has many advantages over traditional joining methods, but remains underutilized. NIST has undertaken an initiative to improve predictions of weldability, reliability, and performance of laser welds. This study investigates butt welding of

Progress toward Radiation-Pressure-Based Measurement of High-Power Laser Emission - Under Policy Review

October 6, 2014
Author(s)
Paul A. Williams, Joshua A. Hadler, Daniel King, Robert Lee, Frank C. Maring, Gordon A. Shaw, Nathan A. Tomlin, John H. Lehman, Marla L. Dowell
We present an overview of our efforts toward using optical radiation pressure as a means to measure optical power from high-power lasers. Early results with measurements ranging from tens of watts to 92 kW prove the concept, but validation uncertainties

Absolute calibration of optical power and fluence rate for PDT: Report of AAPM TG140

July 23, 2013
Author(s)
Marla L. Dowell, Timothy Zhu, Christopher Bonnerup, Valdir Colussi, Jarod Finlay, Lothar Lilge, Thomas Slowery, claudio sibata
This report is primarily concerned with methods for optical calibration of laser power and light fluence rate for continuous wave (CW) light sources, predominantly used in photodynamic therapy (PDT). Dosimetry of light is very important for PDT, however

Random testing reveals excessive power in commercial laser pointers

May 1, 2013
Author(s)
Joshua A. Hadler, Edna L. Tobares, Marla L. Dowell
In random testing of 122 commercial laser pointers, we observed that 89.7 % of green pointers and 44.4 % of red pointers were not in compliance with the Code of Federal Regulations, producing laser power in excess of the Accessible Emission Limit at one or

Accurate, inexpensive testing of handheld lasers for safe use and operation

March 7, 2013
Author(s)
Marla L. Dowell, Joshua A. Hadler
An accurate, inexpensive test bed for measurements of optical power emitted from handheld lasers is described. Our test bed consists of a thermopile detector, bandpass optical filters, an adjustable iris, and self-centering holders for mounting of the

Laser power meter comparison at far infrared wavelengths and terahertz frequencies

August 1, 2012
Author(s)
John H. Lehman, Marla L. Dowell, Nina P. Basta, Kerry N. Betz, Erich N. Grossman
We have evaluated the responsivity of seven different detectors compared to an electrically calibrated photo-acoustic detector at 119 υm (2.5 THz) and 394 υm (0.76 THz) laser wavelengths. Among the detectors is an electrically calibrated thermopile having

Absolute high-power laser measurements with a flowing water power meter

September 18, 2011
Author(s)
Christopher L. Cromer, Xiaoyu X. Li, John H. Lehman, Marla L. Dowell
We describe a novel flowing water power meter (FWOPM) for high-power laser radiometry in the range of 50 W to 10 kW. The FWOPM has several design features; a rotating mirror oriented at 45° with respect to the incoming radiation, a conical light-trapping