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Search Publications by: Paul A. Williams (Fed)

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Displaying 26 - 50 of 229

Inline Laser Power Measurement by Photon Momentum

February 6, 2019
Author(s)
John H. Lehman, Paul A. Williams, Daniel W. Rahn, Kyle A. Rogers
We present a measurement scheme and instrumentation for quantifying laser power by means of photon momentum. The optical design is optimized such that the incoming laser beam is minimally perturbed and is available for other purposes along the incoming

Radiation-Pressure Enabled Traceable Laser Sources at High CW Powers

January 4, 2019
Author(s)
Paul A. Williams, Alexandra B. Artusio-Glimpse, Joshua A. Hadler, Daniel King, Ivan Ryger, Tam Vo, John H. Lehman, Kyle A. Rogers
Radiation pressure has recently been shown to have practical application for multi-kilowatt CW laser power measurement. One key advantage lies in its ability to measure without absorbing the laser beam. This enables a new measurement paradigm where laser

Time-Resolved Absorptance and Melt Pool Dynamics during Intense Laser Irradiation of a Metal

October 25, 2018
Author(s)
Brian J. Simonds, Jeffrey W. Sowards, Joshua A. Hadler, Erik A. Pfeif, Boris Wilthan, Jack R. Tanner, Paul A. Williams, John H. Lehman
Laser welding is a complex, dynamic process by which focused, high-intensity laser light is used to join two metallic surfaces and is being increasing deployed in a variety of industrial applications. Determining the time-dependent absorptance of the laser

Using Radiation Pressure to Develop a Radio-Frequency Power Measurement Technique Traceable to the Redefined SI

October 15, 2018
Author(s)
Christopher L. Holloway, Matthew T. Simons, David R. Novotny, John H. Lehman, Paul A. Williams, Gordon A. Shaw
We discuss a power measurement technique traceable to the International System of Units based on radiation pressure (or radiation force) carried by an electromagnetic wave. A measurement of radiation pressure offers the possibility for a power measurement

MEMS non-absorbing electromagnetic power sensor employing the effect of radiation pressure

September 8, 2018
Author(s)
Ivan Ryger, Aly Artusio-Glimpse, Paul A. Williams, Gordon A. Shaw, Matt Simons, Christopher L. Holloway, John H. Lehman
We demonstrate a compact electromagnetic power sensor based on force effects of electromagnetic radiation onto a highly reflective mirror surface. Unlike the conventional power measurement approach, the photons are not absorbed and can be further used in

Mechanical characterization of planar springs for compact radiation pressure power meters

September 7, 2018
Author(s)
Alexandra B. Artusio-Glimpse, Ivan Ryger, Paul A. Williams, Kyle A. Rogers, Daniel W. Rahn, Andrew J. Walowitz, John H. Lehman
Counter to conventional methods of measuring laser optical power, radiation pressure-based power meters operate by reflection rather than absorption. This provides an opportunity for in situ, non-destructive total beam power measurement. Compact radiation

Dynamic and absolute measurements of laser coupling efficiency during laser spot welds

September 3, 2018
Author(s)
Brian J. Simonds, Jeffrey W. Sowards, Joshua A. Hadler, Erik A. Pfeif, Boris Wilthan, Jack R. Tanner, Chandler Harris, Paul A. Williams
Laser absorptance (coupling efficiency) changes rapidly during laser metal processing due to temperature and multiple phase changes. We find that there is limited literature data available, but this property is vital for accurate process simulations, as

Micromachined force balance for optical power measurement by radiation pressure sensing

August 6, 2018
Author(s)
Ivan Ryger, Alexandra B. Artusio-Glimpse, Paul A. Williams, Nathan A. Tomlin, Michelle S. Stephens, Matthew T. Spidell, Kyle A. Rogers, John H. Lehman
We introduce a micromachined force scale for laser power measurement by means of radiation pressure sensing. With this technique, the measured laser light is not absorbed and can be utilized while being measured. We employ silicon micromachining technology

Point-of-Use, Nonexclusive, High-Power Laser Power Meter

June 19, 2018
Author(s)
Aly Artusio-Glimpse, Ivan Ryger, Paul A. Williams, John H. Lehman
We have developed a small-package, high-power laser power meter that directly measures radiation pressure on a high-reflectivity mirror for nonexclusive, in situ laser measurements without pick- off schemes. Furthermore, our non-inertial design inhibits

Correlation of Neutron-Based Strain Imaging and Mechanical Behavior of Armor Steel Welds Produced with the Hybrid Laser Arc Welding Process

June 11, 2018
Author(s)
Jeffrey W. Sowards, Daniel S. Hussey, David L. Jacobson, Stan Ream, Paul A. Williams
Bragg edge neutron transmission imaging was used to characterize the spatial distribution of thermally induced residual strains in a steel armor plate welded with a hybrid laser arc process. This residual strain distribution was compared to the spatial