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Physics

Optical physics and communications

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Displaying 551 - 575 of 853

Generation of bright phase-matched circularly-polarized extreme ultraviolet high harmonics

December 8, 2014
Author(s)
Justin M. Shaw, Patrik Grychtol, Dmitriy Zusin, Ronny J. Knut, Tenio Popmintchev, Hans T. Nembach, Avner Fleischer, Henry Kapteyn, Margaret Murnane, Ofer Kfir, Oren Cohen
Circularly-polarized extreme UV and X-ray radiation provides valuable access to the structural, electronic and magnetic properties of materials. To date, this capability was available only at large-scale X-ray free-electron lasers or synchrotrons. Here we

Flat lens criterion by small-angle phase

December 1, 2014
Author(s)
Peter Ott, Mohammed H. Al Shakhs, Henri Lezec, Kenneth J. Chau
It is sometimes possible to image using a flat lens consisting of planar, uniform media. There is conceptual division between theoretical flat lens proposals, which require exotic properties such as negative index or counter-intuitive behavior such as

Structural and Dynamical Studies of Acid Mediated Conversion in Amorphous-Calcium-Phosphate Based Dental Composites

October 31, 2014
Author(s)
Fan Zhang, Andrew Allen, Lyle E. Levine, Mark D. Vaudin, Drago Skrtic, Joseph M. Antonucci, Kathleen Hoffman, Anthony A. Giuseppetti, Jan Ilavsky
Amorphous calcium phosphate (ACP) based composites are promising restorative dental materials attributable to ACP's capacity to release calcium and phosphate ions through a complex reaction in which ACP is converted to its crystalline, apatitic form

Path degeneracy and EXAFS analysis of disordered materials

October 24, 2014
Author(s)
Bruce D. Ravel
The analysis of EXAFS data measured on a material with a disordered local configuration environment around the absorbing atom can be challenging due to the proliferation of photoelectron scattering paths that must be considered in the analysis. In the case

Nanoscale Imaging of Photocurrent and Efficiency in CdTe Solar Cells

October 15, 2014
Author(s)
Leite Marina, maxim abashin, Henri Lezec, anthony gianfrancesco, Alec Talin, Nikolai Zhitenev
The local collection characteristics of grain interiors and grain boundaries in thin film CdTe polycrystalline solar cells are investigated using scanning photocurrent microscopy. The carriers are locally generated by light injected through a small

Comb-calibrated laser ranging for three-dimensional surface profiling with micrometer-level precision at a distance

October 6, 2014
Author(s)
Esther Baumann, Fabrizio R. Giorgetta, Jean-Daniel Deschenes, William C. Swann, Ian R. Coddington, Nathan R. Newbury
Non-contact surface mapping at a distance is interesting in diverse applications including industrial metrology, manufacturing, forensics, and artifact documentation and preservation. Frequency modulated continuous wave (FMCW) laser detection and ranging

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

An Average Enumeration Method of Hyperspectral Imaging Data for Quantitative Evaluation of Medical Device Surface Contamination

September 15, 2014
Author(s)
Hanh Le, Moon Kim, Jeeseong C. Hwang, Yi Yang, Pawneena U-Thainual, Jin Kang, Do-Hyun Kim
We propose a quantification method called Mapped Average Principal component analysis Score (MAPS) to enumerate the contamination coverage on common medical device surfaces. The method was adapted from conventional Principal Component Analysis (PCA) on non

Bromination of marine particulate organic matter through oxidative mechanisms

September 14, 2014
Author(s)
Bruce D. Ravel, Alessandra C. Leri, Kathleen Thornton, Lawrence M. Mayer
Although bromine is considered conservative in seawater, it exhibits a well established correlation with organic carbon in marine sediments. This carbon-bromine association was recently attributed to covalent bonding, with organobromine in sinking

Nurturing a Disruptive Technology for Thermodynamic Metrology

September 12, 2014
Author(s)
Zeeshan Ahmed
This presenation lays out a case, based on economic and technologic considerations, that the present technologies for temperature and pressure measurement are ripe for disruption. We argue that a better use of research funds is to identify and nuture

Photon-number uncertainty in a superconducting transition-edge sensor beyond resolved-photon-number determination

September 10, 2014
Author(s)
Zachary H. Levine, Boris L. Glebov, Alan L. Migdall, Thomas Gerrits, Brice R. Calkins, Adriana E. Lita, Sae Woo Nam
As part of an effort to extend fundamental single-photon measurements into the macroscopic regime, we explore how best to assign photon-number uncertainties to output waveforms of a superconducting Transition Edge Sensor (TES) and how those assignments

Absolute pulse energy measurements of soft x-rays at the Linac Coherent Light Source

August 25, 2014
Author(s)
Uwe Arp, Alexander Sorokin, Ulf Jastrow, Pavle Jurani?, Svea Kreis, Mathias Richter, Yiping Feng, Dennis Nordlund, Kai Tiedtke, Philip Heimann, Bob Nagler, Hae Ja Lee, Stephanie Mack, Marco Cammarata, Oleg Krupin, Marc Messerschmidt, Michael Holmes , Michael Rowen, William Schlotter, Stefan Moeller, Joshua Turner
This paper reports novel measurements of x-ray optical radiation on an absolute scale from a recently developed source of radiation generated in the soft x-ray regime of a free electron laser. We give a brief description of the physics behind the

Precision limitations in coherent laser ranging due to speckle phase noise

August 15, 2014
Author(s)
Esther Baumann, Jean-Daniel Deschenes, Fabrizio R. Giorgetta, William C. Swann, Ian R. Coddington, Nathan R. Newbury
The ultimate precision of coherent laser three-dimensional mapping of a diffusely scattering surface will be determined by speckle noise. Speckle phase noise gives rise both to apparent range outliers and to excess range noise during lateral scans

Speckle phase noise in coherent laser ranging: fundamental precision limitations

August 8, 2014
Author(s)
Esther Baumann, Jean-Daniel Deschenes, Fabrizio R. Giorgetta, William C. Swann, Ian R. Coddington, Nathan R. Newbury
Frequency-modulated continuous-wave laser detection and ranging (FMCW LADAR) measures the range to a surface through coherent detection of the backscattered light from a frequency-swept laser source. The ultimate limit to the range precision of FMCW LADAR

High-Speed Coherent Raman Fingerprint Imaging of Biological Tissues

July 20, 2014
Author(s)
Charles H. Camp, Young J. Lee, John M. Heddleston, Christopher M. Hartshorn, Angela R. Hight Walker, Jeremy N. Rich, Justin D. Lathia, Marcus T. Cicerone
We have developed a coherent Raman imaging platform using broadband coherent anti-Stokes Raman scattering (BCARS) that provides an unprecedented combination of speed, sensitivity, and spectral breadth. The system utilizes a unique configuration of laser

Millimeter Wave Detection via Autler-Townes Splitting in Rubidium Rydberg Atoms

July 17, 2014
Author(s)
Joshua A. Gordon, Christopher L. Holloway, Andrew Schwarzkopf, Dave Anderson, Stephanie Miller, Nithiwadee Thaicharoen, Georg Raithel
In this paper we demonstrate the detection of millimeter waves via Autler-Townes splitting in 85Rb Rydberg atoms. This method may provide an independent atomic-based SI-traceable method for measuring mm-wave electric fi elds, which addresses a gap in

Spectral Emissivity Measurements

July 10, 2014
Author(s)
Hiromichi Watanabe, Juntaro Ishii, Hidenobu Wakabayashi, Tomoyuki Kumano, Leonard Hanssen
Chapter 9 describes the wide variety of experimental instrumentation and methods used for spectral emissivity measurements at both ambient and elevated temperatures, along with specific examples of materials studied. There are a number of measurement

Mid-Infrared Time-Resolved Frequency Comb Spectroscopy of Transient Free Radicals

June 10, 2014
Author(s)
Adam J. Fleisher, Bryce Bjork, Thinh Q. Bui, Kevin C. Cossel, Mitchio Okumura, Jun Ye
Quantitative measurements in chemical kinetics require unambiguous determinations of reactant, intermediate, and product concentrations on time scales faster than the reaction rate. Direct absorption spectroscopy in the mid-infrared (mid-IR) can fulfill
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