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A Single Pixel Touchless Laser Tracker Probe

A recent invention within NIST CTL is featured in the 2015 Autumn Journal of the Coordinate Metrology Society Conference*. The invention referred to as the Pixel Probe is new type of spatial metrology probe used with a laser tracker and allows spatial resolution to 25 microns without the need for physical contact. Originally devised to aid in precision millimeter-wave antenna alignment it has broader applications as well. As opposed to other types of non-contact laser tracker probes that use projected light, the Pixel Probe uses a set of cameras. Three machine vision cameras are used to project a single pixel to a location in space that defines the touch-less probe. A single pixel from each camera field of view is then linked to a laser tracker through a calibration process described in the journal paper. The Pixel Probe allows a laser tracker to perform non-contact spatial metrology within a global coordinate system to 25 microns resolution. The benefits derived from this probe will provide data from objects difficult or extremely challenging to measure using existing tracker probes such as objects made of transparent, soft, shiny materials, or objects smaller than 1 millimeter in size without physically contacting the object. Furthermore, this approach allows machine vision derived geometries to be linked to a laser tracker and the approach is scalable to higher-resolution cameras and lenses providing better than the currently available resolution.

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* "A Single Pixel Touchless Laser Tracker Probe", J. A. Gordon, D. R. Novotny, A. E. Curtin, Journal of the CMSC (Autumn 2015)

Released October 27, 2015, Updated September 21, 2016