Measurement and uncertainty evaluation of the microsphere used for micro-CMM probe

A microsphere measurement system based on dual scanning probe microscopes is presented, and the ruby microsphere of a Renishaw commercial stylus used for micro-coordinate measuring machines is measured. The main errors in the measurement are separated and corrected, and the uncertainties of the measured diameter and sphericity are evaluated using the Monte Carlo method. The results indicate that the microsphere diameter is 304.319 m with an expanded uncertainty of 0.027 m (k??=??2), and its sphericity is 0.124 m with an expanded uncertainty of 0.041 m (k??=??2). The measured dimensions of the commercial ruby sphere are consistent with the DIN standard 5401:2002, and the measurement results are accurate and reliable.