Calibration of a Laser Probe on a Miniature Surface Morphology Measurement System for a Spherical Shell
A. Zhou, W. Shao, P. Qu and J. Guo
A surface topography measurement system for spherical shell (STMSSS) consisting of a serial mechanism, a compound sensor with a laser triangulation probe and a charge-couple device (CCD) camera and a turntable is demonstrated. For minimizing the installation error of the laser probe, a new calibration approach based on a designed calibration artefact and an improved genetic algorithm is proposed. In this approach an unconstrained optimization objective function for the parameters, which are included in the error mathematical model for laser probe, can be established by using the constraint that the diameter (or radius) of a measured cross section of the calibration artefact for several different measurements is invariable. Then, an improved genetic algorithm can be used for solving multi-extreme value of objective function. Experimental results on real data have demonstrated the uncertainty of our approach is about 4 μm, and the new method was shown to be less time consuming.
Keywords: Laser probe, spherical shell, miniature surface morphology measurement system, calibration, compound artefact, genetic algorithm