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Displaying 1601 - 1625 of 2606

Computational Parameters in Simulation of Microscope Images

November 28, 2008
Author(s)
Egon Marx, James E. Potzick
The simulation of microscope images computed from scattered fields determined using integral equations depend on a number of parameters that are not related to the scatterer or to the microscope but are choices made for the computation method. The effect

Integral Equations for 3-D Scattering: Finite Strip on a Substrate

November 28, 2008
Author(s)
Egon Marx
Singular integral equations that determine the exact fields scattered by a dielectric or conducting finite strip on a substrate are presented. The computation of the image of such a scatterer from these fields by Fourier optics methods is also shown.

Neutron Transmission of Single-Crystal Magnesium Fluoride

November 27, 2008
Author(s)
John Barker, David F. Mildner, Jose Rodriguez Rivera, P. Thiyagarajan
The neutron attenuation through single-crystal magnesium fluoride has been measured as a function of wavelength at both room temperature and 77 K. These data confirm a total cross section that is lower than MgO for wavelengths greater than 0.2 nm. MgF 2

Calibration of a Computer Assisted Orthopedic Hip Surgery Phantom

November 4, 2008
Author(s)
Daniel S. Sawyer, Nicholas G. Dagalakis, Craig M. Shakarji, Yong Sik Kim
Orthopedic surgeons have identified a need for calibration artifacts (phantoms) to establish the traceability (to the SI unit of length) of measurements performed with Computer Assisted Orthopedic Surgery (CAOS) systems. These phantoms must be lightweight

A COMPACT, COMPOUND ACTUATOR FOR THE MOLECULAR MEASURING MACHINE

October 19, 2008
Author(s)
Jing Li, Yin-Lin Shen, Jaehwa Jeong, Fredric Scire, John A. Kramar
A compact, two-stage, vertical actuator with built-in sensors has been developed for the Molecular Measuring Machine (M3) and other potential precision instrumentation applications, such as scanning probe microscopy (SPM). In this article, we describe the

Error Motions of a Non-orthogonal Rotary Axis

October 19, 2008
Author(s)
Michael L. McGlauflin, Shawn P. Moylan
Error-motions of rotating axes are one of many sources of imprecision in machining. Accurate determination of axis of rotation error motions of the rotary axes has a direct influence on the accuracy of the finished part. International and U.S. national

International photomask linewidth comparison by NIST and PTB

October 17, 2008
Author(s)
James E. Potzick, Ronald G. Dixson, Richard Quintanilha, Michael T. Stocker, Andras Vladar, Egbert Buhr, Bernd Bodermann, Wolfgang Hassler-Grohne, Harald Bosse, C.G. Frase
In preparation of the international Nano1 linewidth comparison on photomasks between 8 national metrology institutes, NIST and PTB have started a bilateral linewidth comparison in 2008, independent of and prior to the Nano1 comparison in order to test the

Using uncalibrated lasers as wavelength standards

October 1, 2008
Author(s)
Jack A. Stone Jr.
The fundamental atomic physics of a gas laser transition is such that the transition frequency, or equivalently, the vacuum wavelength of the laser, cannot vary from its central value by more than a few parts in 106. The uncertainty of the gas laser

Performance Evaluation of Laser Trackers

September 15, 2008
Author(s)
Balasubramanian Muralikrishnan, Daniel S. Sawyer, Christopher J. Blackburn, Steven D. Phillips, Bruce R. Borchardt, William T. Estler
The American Society for Mechanical Engineers (ASME) recently released the ASME B89.4.19 Standard [1] on performance evaluation of spherical coordinate instruments such as laser trackers. At the National Institute of Standards and Technology (NIST), we can

Accuracy Considerations for Critical Dimension Semiconductor Metrology

September 9, 2008
Author(s)
Ronald G. Dixson, Ndubuisi G. Orji, B Bunday, J Allgair
As the size of integrated circuit features continues to decrease, the accuracy of measurements becomes more important. Due to greater emphasis on precision rather than accuracy, many of the measurements made in semiconductor fabs are not traceable to the

Through-focus Scanning and Scatterfield Optical Methods for Advanced Overlay Target Analysis

September 1, 2008
Author(s)
Ravikiran Attota, Michael T. Stocker, Richard M. Silver, Nathanael A. Heckert, Hui Zhou, Richard J. Kasica, Lei Chen, Ronald G. Dixson, Ndubuisi G. Orji, Bryan M. Barnes, Peter Lipscomb
In this paper we present overlay measurement techniques that use small overlay targets for advanced semiconductor applications. We employ two different optical methods to measure overlay using modified conventional optical microscope platforms. They are

NIST Microform Calibration System for Rockwell Hardness Standardization

August 25, 2008
Author(s)
Jun-Feng Song, Samuel R. Low III, Xiaoyu A. Zheng
In the uncertainty budget of Rockwell hardness tests, microform geometric errors of the diamond indenter are a major contributor. The microform calibration of Rockwell diamond indenters has been one of the key steps for Rockwell hardness standardization

Performance of Super-Resolution Enhancement for Flash LADAR Data

August 21, 2008
Author(s)
Tsai Hong Hong, Shuowen Hu, S. S. Young
Flash laser detection and ranging (LADAR) systems are increasingly used in robotics applications for autonomous navigation and obstacle avoidance. Their compact size, high frame rate, wide field of view, and low cost are key advantages over traditional

Measuring the Phase Transfer Function of a Phase-Shifting Interferometer

August 13, 2008
Author(s)
JiYoung Chu, Quandou (. Wang, John P. Lehan, Ulf Griesmann, Guangjun Gao
In characterizing the performance of a phase-shifting interferometer, the dependence of the measured height on the spatial frequency is rarely considered. We describe a test mirror with a special height relief that can be used to measure the height

Capillary flow meter for calibrating spinning rotor gauges

August 6, 2008
Author(s)
Robert F. Berg
This article describes a capillary flow meter whose maximum flow rate of 0.2 micromol/s (~0.2 cm3/min at ambient conditions) covers the range that is useful for calibrating spinning rotor gauges. Knowing the input pressure, output pressure, and temperature

Cellulose Nanocrystals the Next Big Nano-thing?

August 6, 2008
Author(s)
Michael T. Postek, Andras Vladar, John A. Dagata, Natalia Farkas, Bin Ming, Ronald Sabo, Theodore H. Wegner
Biomass surrounds us from the smallest alga to the largest redwood tree. Even the largest trees owe their strength to a newly-appreciated class of nanomaterials known as cellulose nanocrystals (CNC). Cellulose, the world s most abundant natural, renewable

Measurement Time and Statistics for a Noise Thermometer With a Synthetic-Noise Reference

August 1, 2008
Author(s)
David R. White, Samuel Benz, J Labenski, Sae Woo Nam, Jifeng Qu, H Rogalla, Weston L. Tew
This paper describes methods for reducing the statistical uncertainty in measurements made by noise thermometers using digital cross correlators, and in particular, for thermometers using pseudorandom noise for the reference signal. First, a discrete
Displaying 1601 - 1625 of 2606