A Single Pixel Touchless Laser Tracker Probe

Abstract

We have developed a laser tracker probe that does not require physically contacting the object one is measuring and which has 3D spatial resolution of ~25 microns (in x,y,z) in the current configuration. This touchless laser tracker probe uses three machine vision cameras to discretize a scene down to the spatial resolution of a pixel. A single pixel from the camera field of view is linked to a laser tracker through a calibration process. This pixel defines a point in space that is used as a virtual touch probe where one places the pixel on an object by means of viewing the camera images. This allows one to measure with a laser tracker the location of small features (tens of microns) on an object without needing physical contact. Given that the design of this system is easily scalable to higher resolution cameras and lenses, it is envision that this system could provide better than the current 25 micron resolution. This laser tracker probe excels at measuring objects that may prove difficult for existing laser tracker probes such as, sharp edges, and corners. In addition one can register features that appear in the images, and or geometries that are derived using machine vision algorithms to the laser tracker. We present the concept, design, function, calibration, and operation of this system. Several measurements are presented.