U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by: Daniel S. Sawyer (Fed)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 101 - 125 of 143

ASME B89.4.19 Performance Evaluation Tests and Geometric Misalignments in Laser Trackers

January 30, 2009
Author(s)
Balasubramanian Muralikrishnan, Daniel S. Sawyer, Christopher J. Blackburn, Steven D. Phillips, Bruce R. Borchardt, William T. Estler
Small and unintended offsets, tilts, and eccentricity of the mechanical and optical components in laser trackers introduce systematic errors in the measured spherical coordinates (angles and range readings), and possibly in the calculated lengths of

A Low Cost Fiducial Reference for Computed Tomography

November 11, 2008
Author(s)
Zachary H. Levine, Steven Grantham, Daniel S. Sawyer, Anthony P. Reeves, David F. Yankelevitz
Rationale and Objectives. To detect the growth in lesions, it is necessary to ensure that the apparent changes in size are above the noise floor of the system. By introducing a fiducial reference, it may be possible to detect smaller changes in lesion size

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

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

Laser Tracker Testing at NIST Using the ASME B89.4.19 Standard

January 1, 2007
Author(s)
Balasubramanian Muralikrishnan, Christopher J. Blackburn, Daniel S. Sawyer, Bruce R. Borchardt, William T. Estler, Steven D. Phillips
While the versatility and economics of laser trackers are quite appealing, the ability to assess their accuracy and to compare various brands has been limited by a lack of a national or international standard that encompasses testing and traceability

Large-Scale Metrology Instrument Performance Evaluations at NIST

January 1, 2006
Author(s)
William T. Estler, Daniel S. Sawyer, Bruce R. Borchardt, Steven D. Phillips
The ASME B89 Committee on Dimensional Metrology has approved a new American National Standard B89.4.19 - Performance Evaluation of Laser Based Spherical Coordinate Measurement Systems. This Standard, to be published in 2006, specifies test methods for

Validation of CMM Task Specific Measurement Uncertainity Software

August 1, 2003
Author(s)
M P. Henke, J M. Baldwin, K Summerhays, B Rasnick, P Murray, Daniel S. Sawyer, Bruce R. Borchardt, Steven D. Phillips, Craig M. Shakarji
Task specific CMM measurement uncertainty statements can be generated using computer (Monte Carlo) simulation. REcently, commercial products using this powerful technique have become available; however they typically involve megabytes of code inaccessible

The Validation of CMM Task Specific Measurement Uncertainty Software

January 1, 2003
Author(s)
Steven D. Phillips, Bruce R. Borchardt, A Abackerli, Craig M. Shakarji, Daniel S. Sawyer, P Murray, B Rasnick, K Summerhays, J M. Baldwin, M P. Henke
Task specific CMM measurement uncertainty statements can be generated using computer (Monte Carlo) simulation. Recently, commercial products using this powerful technique have become available; however they typically involve megabytes of code inaccessible

A Laser Tracker Calibration System

January 1, 2002
Author(s)
Daniel S. Sawyer, Bruce R. Borchardt, Steven D. Phillips, Charles Fronczek, William T. Estler
We describe a laser tracker calibration system developed for frameless coordinate metrology systems. The system employs a laser rail to provide an 'in situ' calibrated length standard that is used to test a tracker in several different configurations. The