Area-based optical 2.5D sensors of a nanopositioning and nanomeasuring machine

At the Ilmenau University of Technology, work has been continuing on nanopositioning and nanomeasuring machines (NPMMs), which allow users to perform highly exact dimensional and traceable positioning with sub-nanometre resolution and nanometre uncertainty within a measuring volume of 25 mm × 25 mm × 5 mm. The NPMM can work with various probe systems operating in the z-direction, including atomic force microscopes, focus sensors and tactile probes. However, point-by-point measurement of the entire 25 mm × 25 mm area would take a prohibitively long time. This paper presents two area-based optical sensors as an alternative scanning approach. The use of these sensors can significantly reduce the time required for measurements of the entire scannable area. The methods used are white light interferometry and depth from focus. The use of the NPMM for these tasks adds the ability for high-accuracy positioning, which is necessary in order to use several special stitching methods which can reduce the propagation of uncertainty normally introduced by standard stitching. (paper)