A position sensitive detector (PSD) has been used to determine the diameter of cylindrical pins based on the shift in a laser beam's centroid. The centroid of the light beam is defined here as the weighted average of position by the local intensity. A shift can be observed in the centroid of an otherwise axially symmetric light beam, which is partially obstructed. Additionally, the maximum shift in the centroid is a unique function of the obstructing cylinder diameter. Thus to determine the cylinder diameter, one only needs to detect this maximum shift as the cylinder is swept across the beam.
© 2007 Optical Society of America
Original Manuscript: July 9, 2007
Revised Manuscript: August 30, 2007
Manuscript Accepted: August 30, 2007
Published: October 11, 2007
W. Doyle St. John, "Cylinder gauge measurement using a position sensitive detector," Appl. Opt. 46, 7469-7474 (2007)