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Tech Talk – Why Laser Trackers with OTG are Important for Industrial Applications

Written by Hubert Meagher, OASIS Director of Metrology Services, this post recently appeared on the Talking Points Blog published by Hexagon Manufacturing Intelligence. In future posts, we will provide additional technical information on the capabilities of our AT960 laser trackers and also delve deeper into the benefits to our customers of our using this innovative laser tracker for gathering highly accurate dimensional measurements at their location.  

Orient-To-Gravity (OTG) is a standard feature on the Leica AT960 laser tracker and it is arguably one of the most important for OASIS. As a service company providing 3D metrology services to many different industries, we often have applications that require a reference level-to-Earth. With more traditional optical alignment technologies, level-to-Earth was not only a requirement for the object of the inspection, but it was essential in order to use the instruments properly. For most machinery, being level-to-Earth is normally a best practice, if not outright essential, for proper function, whereas certain tooling could be out of level and still be in tolerance and perfectly operable. Most tooling is still specified to be level-to-Earth whether by best practice or just by design legacy.

Leica AT960 Laser Trackers with OTG feature are ideal in industrial settings

Leica AT960 Laser Trackers with OTG feature are ideal in industrial settings

When using traditional optical tooling, precision levelling has always been a part of utilizing the instruments. When laser trackers were first used in manufacturing, they did not have level-to-Earth capabilities and so were mainly used to inspect parts, assemblies, and tooling after the fixture was leveled by other means.

Once laser trackers began to incorporate precision levels in order to expand their capabilities in general industry outside of aerospace and automotive, the process of levelling was a separate measurement step that needed to be taken. The data was then incorporated into the metrology software to compensate coordinate systems in order to show objects relative to a level plane.

With Leica’s OTG, the laser tracker has truly become a seamless 3D measurement device that is compensated for level from within. Much like traditional optics, after the instrument is “levelled”, the data and readings coming from the device are based on coordinates that are compensated. What that means for us is three fold:

  1. The operator no longer has to be concerned with creating a level coordinate system from a level plane derived from a level measurement process. The operator simply has to ensure the laser tracker is rough levelled within tolerance and the OTG option is checked in our metrology software.
  1. When OTG is activated on the first device position of a project, by definition the World coordinates become level-to-Earth. No longer is there a confusing difference between device coordinates, level coordinates, and World coordinates.
  1. Since each new device can be compensated level-to-Earth, we now have a very real constant between device positions. We can now constrain device position moves to their respective “level planes” or “Z” axis. Gone are the days where drifting reference targets (in the vertical attribute) would create havoc on a project. Also gone are the very real concerns about translating devices down long and narrow corridors or machine alleys. By constraining to level at every device position along a very long machine, we can ensure that the cross-machine level is constant at every device position.

We here at OASIS are very pleased to have a fleet of laser trackers with level capabilities that not only allows us to level machines, equipment, and tooling, but also make the measurement process itself even more accurate.

If you would like to learn more about how OASIS metrology engineers use Leica AT960 laser trackers in your industry,  please contact us. To receive regular updates on precision measurement tools and technologies, case studies and industry news, please subscribe to our blog.

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