Surface topography characterization using an atomic force microscope mounted on a coordinate measuring machine

The paper describes the construction, testing and use of an integrated system for topographic characterization of fine surfaces on parts having relatively big dimensions. An atomic force microscope (AFM) was mounted on a manual three-coordinate measuring machine (CMM) achieving free positioning of the AFM probe in space. This means that the limited measuring range of the AFM (40 mu m x 40 mu m x 2.7 um) can be extended by positioning the AFM probe using the movements of the CMM axes (400 mm x 100 mm x 75 mm). Evaluation of the background noise by determining the Sa value of an optical fiat gave values in the order of 1 nm. The positioning repeatability of the two horizontal axes of the CMM was determined to +/-1 mu m. Sets of four 20 mu m x 20 mu m areas were traced on fiat objects, combining the data into single 40 mu m x 40 mu m areas, and comparing the roughness values to those for the same areas traced in single scans of 40 mu m x 40 mu m. The results show that surface mapping on industrial surfaces is possible using the Least Mean Square alignment provided by the AFM software.