Product Code: JLA_2_2_33

Authors:
Paul G. Backes
Warren H. Stevenson
School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907

Optical methods for the measurement of position, part dimensions, or alignment are finding increased application in manufacturing operations. Several of these methods utilize analog or digital position sensitive detectors to find the centroid of an illuminated spot on the detector. The objective of this study was to determine the accuracy with which the centroids of a direct laser beam and a circular incoherent image could be determined using a matrix array sensor. Centroids were found using five different analytical methods. The results showed that a simple intensity centroid computation was as accurate as more complex analytical schemes. Maximum errors of less than 1/20 pixel were found for both the laser beam and incoherent image centroids when their diameters were approximately 40 pixels. The effect of laser beam wander on accuracy was also investigated.