NIST: Virtual Tracker Optical Path Simulator
The New River Kinematics (NRK) Virtual Tracker was developed under contract with the National Institute of Standards and Technology. The goal was to provide an optical path kinematic simulator for determining the uncertainty resulting from a laser tracker measurement system. The result is a powerful simulator that can be used to model many types of optical trains and evaluate their sensitivity to kinematic and other errors in the physical components.NIST: Virtual Tracker Optical Path Simulator
The New River Kinematics (NRK) Virtual Tracker was developed under contract with the National Institute of Standards and Technology. The goal was to provide an optical path kinematic simulator for determining the uncertainty resulting from a laser tracker measurement system. The result is a powerful simulator that can be used to model many types of optical trains and evaluate their sensitivity to kinematic and other errors in the physical components.
Laser Trackers have quickly become an indispensable part of our nation’s manufacturing base. Although these devices initially found application in the automotive and aircraft industries, they are finding rapid and widespread acceptance in numerous other arenas such as satellite communications, nuclear power plant maintenance, and large-scale high speed roll alignment.
In order for these industries to remain competitive and meet ISO 9000 and ISO Guide 25 measurement accreditation, there must be an established uncertainty estimation procedure for the coordinates produced by laser trackers.
The virtual laser tracker concept provides a convenient and cost effective method for obtaining realistic coordinate uncertainty estimates. Metrologists can apply the resulting methods to test measurement geometries and thereby design measurement configurations to reduce coordinate uncertainty. Furthermore, since this approach does not rely on large expensive touchstone artifacts, the methodology is readily adapted for small operations with limited space and modest resources and would be equally applicable for field checks of instruments as well.
NRK’s resulting software package, the Virtual Laser Tracker (VLT), models and predicts the task-specific measurement uncertainty of a laser-based spherical coordinate measurement devices (Laser Trackers). This product is in no way limited to this class of instrumentation, but this configuration has served as a proof-of-concept example.
The screen shots shown briefly demonstrate the functionality of the Virtual Tracker software package. First, we will present the modeling steps for producing a simple laser tracker model:
- Step 1: Laser Source Added
- Step 2: First Mirror Added
- Step 3: Cube Beam Splitter Added
- Final Step: Model with Quad-Cell and Beam Path
The Virtual Tracker is also capable of modeling the beam profile as it travels through the optical train.
In addition, the user can specify the amount of noise that is to be injected into the transformations of the optical components as well as the weather parameters.
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