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Search Publications by: John H. Lehman (Fed)

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Displaying 26 - 50 of 163

Calibration of free-space and fiber-coupled single-photon detectors

December 20, 2019
Author(s)
Thomas Gerrits, Alan L. Migdall, Joshua C. Bienfang, John H. Lehman, Sae Woo Nam, Jolene D. Splett, Igor Vayshenker, Chih-Ming Wang
We measure the detection efficiency of single-photon detectors at wavelengths near 851 nm and 1533.6 nm. We investigate the spatial uniformity of one free-space-coupled single-photon avalanche diode and present a comparison between fusion-spliced and

Optical-Fiber Power Meter Comparison between NIST and LAMETRO

November 1, 2019
Author(s)
Johnny Jimenez, Maria Ugalde, John H. Lehman, Igor Vayshenker
We describe the results of a comparison of reference standards between the National Institute of Standards and Technology (NIST-USA) and Laboratorio de Metrologia, Instituto Costarricense de Electricidad (LAMETRO-ICE, COSTA RICA) for optical fiber-based

Compact total irradiance monitor: Flight demonstration

August 30, 2019
Author(s)
Dave Harber, John H. Lehman, Nathan A. Tomlin, Christopher Yung, Malcolm White, Zach Castleman, Ginger Drake, Samuel Van Dreser, Nat Farber, Karl Heurman, Joel Rutkowski, Alan Sims, Jacob Sprunck, Cameron Straatsma, Isaac Wanamaker, Wengang Zheng, Greg Kopp, P. Pilewskie, Michelle Stephens
The long-term balance between Earth's absorption of solar energy and emission of radiation to space is a fundamental climate measurement. Total solar irradiance (TSI) has been measured from space, uninterrupted, for the past 40 years via a series of

BABAR: Black Array of Broadband Absolute Radiometers for far infrared sensing

May 13, 2019
Author(s)
Christopher S. Yung, Nathan A. Tomlin, Cameron Straatsma, Joel Rutkowski, Erik Richard, Dave Harber, John H. Lehman, Michelle S. Stephens
Currently at NIST, there is an effort to develop a black array of broadband absolute radiometers (BABAR) for far infrared sensing. The linear array of radiometer elements is based on uncooled vanadium oxide (VOx) microbolometer pixel technology but with

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

Cryogenic Primary Standard for Optical Fibre Power Measurement

August 17, 2018
Author(s)
Malcolm G. White, Zeus Ruiz, Christopher S. Yung, Igor Vayshenker, Nathan A. Tomlin, Michelle S. Stephens, John H. Lehman
NIST has completed commissioning a new, state-of-the-art cryogenic primary standard for optical fibre power measurement and calibration. It establishes for the first time, a direct traceability route between the device under test and primary standard. Two

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

Characterisation of New Planar Radiometric Detectors using Carbon Nanotube Absorbers under Development at NIST

June 13, 2018
Author(s)
Malcolm G. White, Nathan A. Tomlin, Christopher S. Yung, Michelle S. Stephens, Ivan Ryger, Solomon I. Woods, John H. Lehman, Igor Vayshenker
Carbon nanotube technology, in conjunction with silicon micro-fabrication techniques, has enabled us to develop planar radiometric detectors, which has led to the establishment of a new generation of primary standards. The goal is to develop compact, fast

Reduction of Short Wavelength Reflectance of Multi-wall Vertically Aligned Carbon Nanotubes Through UV Laser Irradiation

May 29, 2018
Author(s)
Michelle S. Stephens, Brian J. Simonds, Christopher S. Yung, Davis R. Conklin, David J. Livigni, Alberto R. Oliva, John H. Lehman
Multi-wall carbon nanotube coatings are used as broadband, low-reflectance absorbers for bolometric applications, blackbody radiators, and for stray light control. Irradiation of single wall carbon nanotubes with UV laser light has been shown to remove

Optical Measurements of Dynamic Absorptance during High-power Laser Spot Welding

May 7, 2018
Author(s)
Brian Simonds, Jeffrey W. Sowards, Joshua A. Hadler, Boris Wilthan, Erik A. Pfeif, Jack R. Tanner, Chandler Harris, Paul A. Williams, John Lehman
We present precision measurements of the time-dependent absorptance during a 10 ms fiber-laser spot weld on 316L stainless steel. From these, the precise time and energy at which a keyhole is formed can be determined.

Carbon Nanotube-Based Black Coatings

February 15, 2018
Author(s)
John H. Lehman, Christopher S. Yung, Nathan A. Tomlin, Davis R. Conklin, Michelle S. Stephens
It has been shown that coatings comprised of carbon nanotubes are very black; that is, characterized by low reflectance over a broad wavelength range from the visible to far infrared. Arguably there is no other material that is comparable. This is

Geometric contributions to chopper wheel optical attenuation uncertainty

December 9, 2017
Author(s)
Matthew T. Spidell, Joshua A. Hadler, Michelle S. Stephens, John H. Lehman, Paul A. Williams
Calibrated reflective optical choppers are used in NIST’s high power laser calibration services due to their advantages in performance and safety over wedges and semi-transparent materials for beam power reduction. While the design, operation, and

On-site multi-kilowatt laser power meter calibration using radiation pressure

December 1, 2017
Author(s)
Paul A. Williams, Joshua A. Hadler, Brian J. Simonds, John H. Lehman
We have demonstrated the calibration of a thermal power meter against a radiation-pressure power meter in the range of 20 kW in a manufacturing test environment. The results were compared to a traditional calorimeter-based laboratory calibration undertaken

Plasma modification of vertically aligned carbon nanotubes: superhydrophobic surfaces with ultra- low reflectance

November 2, 2017
Author(s)
Christopher S. Yung, Nathan A. Tomlin, Karl Heuerman, Mark W. Keller, Malcolm G. White, Michelle S. Stephens, John H. Lehman
Vertically aligned carbon nanotubes (VACNTs) are excellent broadband (UV–VIS–IR) absorbers of light that can be made even darker with plasma treatments. Modification of VACNTs using O2 and/or CF4 plasmas is shown to have a significant impact on the

Verification of Calibration Methods for Determining Photon-Counting Detection Efficiency using Superconducting Nano-Wire Single Photon Detectors

September 4, 2017
Author(s)
Igor Vayshenker, Robert D. Horansky, John H. Lehman, Malcolm G. White, Sae Woo Nam, Ingmar Mueller, Lutz Werner, G. Wuebbeler
In the recent years several ways to radiometrically calibrate optical fiber-coupled detectors have been developed. However, fiber-coupled calibration methods for single photon detectors have not been compared by national metrology institutes validating the

Prototype Tests of a Miniature Radiation Pressure Sensor

July 2, 2017
Author(s)
Alexandra B. Artusio-Glimpse, Paul A. Williams, Nathan A. Tomlin, Ivan Ryger, Michelle S. Stephens, John H. Lehman
Using reflection, radiation pressure (RP) sensors provide a means for in-situ power measurement simply and accurately. The first realization of multi-kW RP power meters (RPPM) established a new paradigm of optical power measurement technology [1]. Our
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