This paper presents a ball-bar based self-calibration technique for a five-axis point laser optical measurement system. The system is composed of a high accuracy laser point sensor and five motion stages X, Y, Z, B, C. A kinematical system model of the 5-axis measurement system is presented to map the stages and sensor readouts to the target position of the work piece to be measured. With an assumption that each stages’ linearity error, straightness errors, angular errors and sensor linearity error have been calibrated or omitted due to high performance hardware selection, the three squareness angles, laser beam direction and rotary axis position and direction of the two rotary stages are well addressed as the model parameters in the system model. Heuristic methods are introduced to separately calibrate the system squareness, beam direction and rotary axis by using different data acquisition approaches over the ball bar. Parameter estimation methods are applied to obtain the system model parameters via the data set of the ball bar. Experimental studies using a cylinder bar and ball bar demonstrate that the system achieved an accuracy of better than 5 micron.

Date Published: 4 December 2012
PDF: 8 pages
Proc. SPIE 8563, Optical Metrology and Inspection for Industrial Applications II, 856308 (4 December 2012); doi: 10.1117/12.2001247

Published in SPIE Proceedings Vol. 8563:
Optical Metrology and Inspection for Industrial Applications II
Kevin G. Harding; Peisen S. Huang; Toru Yoshizawa, Editor(s)