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Search Publications by: Daniel S. Sawyer (Fed)

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Displaying 26 - 50 of 71

Targets for Relative Range Error Measurement of 3D Imaging Systems.

July 25, 2016
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Katharine M. Shilling, Geraldine S. Cheok, Vincent D. Lee, Christopher J. Blackburn, Dennis S. Everett, Daniel S. Sawyer
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) is performing research to support the development of documentary standards within ASTM E57 for the point-to-point performance evaluation of 3D imaging

Laser Trackers for Large Scale Dimensional Metrology: A Review

March 25, 2016
Author(s)
Balasubramanian Muralikrishnan, Steven D. Phillips, Daniel S. Sawyer
Thirty years since their invention, laser trackers are now recognized as the measurement tool of choice in the manufacture and assembly of large components. While their general design, i.e., a ranging unit on a two-axis gimbal, has not changed

Performance evaluation of a laser tracker hand held touch probe

November 4, 2015
Author(s)
Bala Muralikrishnan, Christopher J. Blackburn, Prem K. Rachakonda, Daniel S. Sawyer
Hand-held touch probes and laser scanners are increasing the scope and applicability of laser trackers. While methods to evaluate the performance of laser trackers in conjunction with spherically-mounted retro-reflectors (SMRs) are well established

Evaluation of the Range Performance of Laser Scanners Using Non-planar Targets.

November 1, 2015
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Craig M. Shakarji, Vincent D. Lee, Daniel S. Sawyer
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) is supporting the development of documentary standards for performance evaluation of Laser scanners. This evaluation could be performed by determining the

Towards the Development of a Documentary Standard for Derived-Point to Derived-Point Distance Performance Evaluation of Spherical Coordinate 3D Imaging Systems

October 30, 2015
Author(s)
Balasubramanian Muralikrishnan, Katharine M. Shilling, Prem K. Rachakonda, Wei Ren, Vincent D. Lee, Daniel S. Sawyer
This paper describes ongoing research work within the Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) in support of the development of a documentary standard for derived-point to derived-point distance

Techniques to Evaluate Laser Scanners for Advanced Manufacturing Applications

July 23, 2015
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Katharine M. Shilling, Daniel S. Sawyer, Geraldine S. Cheok, Kamel S. Saidi
Laser scanners have become indispensable tools for fast and accurate 3D image acquisition applications such as part inspection, reverse engineering, cultural heritage digitization, surveying, automotive robotic navigation etc. The Dimensional Metrology

Considerations for Design and In-Situ Calibration of High Accuracy Length Artifacts for Field Testing of Laser Trackers

March 1, 2015
Author(s)
Aaron Hudlemeyer, Daniel S. Sawyer, Christopher J. Blackburn, Vincent Lee, Mark Meuret, Craig M. Shakarji
Interim testing of laser trackers can be problematic due to the lack of high precision, long length artifacts that maintain their calibrated lengths during measurement. Gravitational loading, fixturing forces, and changes in the atmospheric conditions can

Volumetric Performance Evaluation of a Laser Scanner Based on Geometric Error Model

January 5, 2015
Author(s)
Balasubramanian Muralikrishnan, Massimiliano M. Ferrucci, Daniel S. Sawyer, Grant Gerner, Vincent D. Lee, Christopher J. Blackburn, Steven D. Phillips, Yuri Yakovlev, Andrey Astrelin, Spike Milligan, John Palmateer
We discuss a geometric error model for those large volume laser scanners that have the laser source and a spinning prism mirror mounted on a platform that can rotate about the vertical axis. We describe the terms that constitute the model, address their

In-situ Temperature Calibration Capability for Dimensional Metrology

December 15, 2014
Author(s)
Prem K. Rachakonda, Daniel S. Sawyer, Balasubramanian Muralikrishnan, Christopher J. Blackburn, Craig M. Shakarji, Gregory F. Strouse, Steven D. Phillips
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) has developed a new in-situ temperature calibration system. This paper discusses the system components, an in-situ calibration procedure, the uncertainty

In-situ Temperature Calibration Capability for Dimensional Metrology

December 1, 2014
Author(s)
Prem K. Rachakonda, Daniel S. Sawyer, Balasubramanian Muralikrishnan, Christopher J. Blackburn, Craig M. Shakarji, Gregory F. Strouse, Steven D. Phillips
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) has the capability to perform large range dimensional measurements in a facility, called the Tape Tunnel. The Tape Tunnel is equipped with a 60 m long steel

A Method of Determining Sphere Center to Center Distance Using Laser Trackers For Evaluating Laser Scanners.

November 11, 2014
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Vincent D. Lee, Daniel S. Sawyer, Steven D. Phillips, John Palmateer
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) is involved in the development of documentary standards for volumetric performance evaluation of laser scanners. Typical evaluation of these scanners

Laser scanner two-face errors on spherical targets

November 11, 2014
Author(s)
Balasubramanian Muralikrishnan, Katharine M. Shilling, Daniel S. Sawyer, Prem K. Rachakonda, Vincent D. Lee, Steven D. Phillips, Geraldine S. Cheok, Kamel S. Saidi
Geometric misalignments within the construction of a laser scanner such as offsets, tilts, and eccentricities, result in systematic errors in the measured point coordinates (range and angles). Many of these sources of error are sensitive to two-face

POINT REMOVAL FOR FITTING SPHERES TO 3-D LASER SCANNER DATA

November 11, 2014
Author(s)
Katharine M. Shilling, Balasubramanian Muralikrishnan, Daniel S. Sawyer
The proliferation of laser scanners in a number of industries such as the metrology of large artifacts, digitization and reverse engineering, historical preservation and archiving has led to the need for documentary Standards to establish and compare the

A Proposed Interim Check for Field Testing a Laser Tracker’s 3-D Length Measurement Capability Using a Calibrated Scale Bar as a Reference Artifact

October 1, 2014
Author(s)
Vincent D. Lee, Christopher J. Blackburn, Balasubramanian Muralikrishnan, Daniel S. Sawyer, Mark Meuret, Aaron Hudlemeyer
This paper describes a proposed interim check for field testing a laser tracker’s 3-D length measurement capability using a calibrated scale bar as a reference artifact. The tests described here are constructed to be sensitive to uncompensated errors in

EVALUATION OF A LASER SCANNER FOR LARGE VOLUME COORDINATE METROLOGY - A COMPARISON OF RESULTS BEFORE AND AFTER FACTORY CALIBRATION

October 1, 2014
Author(s)
Massimiliano Ferrucci, Bala Muralikrishnan, Daniel S. Sawyer, Steven D. Phillips, Peter Petrov, Yuri Yakovlev, Andrey Astrelin, Spike Milligan, John Palmateer
Large volume laser scanners are increasingly being used for a variety of dimensional metrology applications. Methods to evaluate the performance of these scanners are still under development and there are currently no documentary standards available. This

Common-Path Method for Laser Tracker Ranging Calibration

March 31, 2014
Author(s)
Christopher J. Blackburn, Daniel S. Sawyer, Craig M. Shakarji
We present an alternative to the back-to-back method of testing laser tracker ranging systems. Our approach uses a common air path for both the measurement and reference laser beams. This technique allows for more accurate determination of the reference

Ranging Performance Evaluation of a Laser Scanner

October 20, 2013
Author(s)
Massimiliano M. Ferrucci, Balasubramanian Muralikrishnan, Christopher J. Blackburn, Daniel S. Sawyer, Steven D. Phillips, Vincent D. Lee, Peter Petrov, Yuri Yakovlev, Andrey Astrelin, Spike Milligan, John Palmateer
Large volume laser scanners are used for a variety of purposes, including dimensional metrology of large artifacts, digitization and reverse engineering, as well as historical preservation and archiving. In evaluating the performance of laser scanners, we

VOLUMETRIC PERFORMANCE EVALUATION OF A LASER SCANNER

October 20, 2013
Author(s)
Balasubramanian Muralikrishnan, Massimiliano M. Ferrucci, Daniel S. Sawyer, Grant Gerner, Vincent D. Lee, Christopher J. Blackburn, Steven D. Phillips, Peter Petrov, Yuri Yakovlev, Andrey Astrelin, Spike Milligan, John Palmateer
There are several sources of error in a laser scanner measurement. The optical and material properties of the target, the shape, form, surface texture, color, reflectivity, and orientation of the target in space, environmental effects, etc., all contribute

Standard Reference Materials for Medical CT

June 27, 2013
Author(s)
Zachary H. Levine, Huaiyu H. Chen-Mayer, Adam L. Pintar, Daniel S. Sawyer
NIST Standard Reference Materials 2087 and 2088 for medical computed tomography (CT) have become available. The materials allow CT reconstructions to be tied to the International System of Units in length, density, and mass attenuation coefficient.

Assessing Ranging Errors as a Function of Azimuth in Laser Trackers and Tracers

April 18, 2013
Author(s)
Balasubramanian Muralikrishnan, Vincent D. Lee, Christopher J. Blackburn, Daniel S. Sawyer, Steven D. Phillips, Wei Ren, Ben Hughes
Tilt and radial error motion of a laser tracker head as it spins about the two axes results in small but measurable ranging and angle errors. The laser tracer, on the other hand, measures range with respect to the center of a high quality stationary sphere

A Model for Geometry-Dependent Errors in Length Artifacts

September 27, 2012
Author(s)
Daniel S. Sawyer, Brian Parry, Christopher J. Blackburn, Balasubramanian Muralikrishnan, Steven D. Phillips
We present a detailed model of dimensional changes in long length artifacts, such as step gauges and ball bars, due to bending under gravity. The comprehensive model is based on evaluation of the gauge points relative to the neutral bending surface. It

Measuring Scale Errors in a Laser Tracker s Horizontal Angle Encoder through Simple Length Measurement and Two-face System Tests

November 1, 2010
Author(s)
Balasubramanian Muralikrishnan, Christopher J. Blackburn, Daniel S. Sawyer, Steven D. Phillips, Robert Bridges, Quan Ma
We describe a method to estimate the scale errors in the horizontal angle encoder of a laser tracker in this paper. The method does not require expensive instrumentation such as a rotary stage or even a calibrated artifact. An uncalibrated but stable

Choosing test positions for laser tracker evaluation and future Standards development

July 15, 2010
Author(s)
Balasubramanian Muralikrishnan, Daniel S. Sawyer, Christopher J. Blackburn, Steven D. Phillips, Craig M. Shakarji, Ed Morse, Robert Bridges
A working group within the ISO TC 213 committee is developing a draft document [11] for evaluating the performance of laser trackers. The ASME B89.4.19 Standard [1] and the draft VDI/VDE 2617 part 10 [2] describe some useful tests that are incorporated

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