Improvement of measuring accuracy of an optical CMM

In this paper, a laser interferometer was used to evaluate the linear performance of an optical coordinate measuring machine with a measuring area of 400 mm x 400 mm at 20-mm interval. The evaluation results show that the linear performance of the Y-axis varies a lot at different X positions and offline error compensation method was implemented. A 200 mm glass scale was used to verify the method. The results showed that the variations at different X positions improved from 0.35 μm to 0.15 μm within the compensated area. A better measurement uncertainty was also achieved.