Interference signal demodulation for nanopositioning and nanomeasuring machines

The nanopositioning and nanomeasuring machine NMM-1 developed at the Ilmenau University of Technology was designed for measurements within a measuring volume of 25 x 25 x 5 mm(3). The interferometric length measuring and drive systems make it possible to move the stage and corner mirror with a resolution of 0.1 nm in all three axes. The object being measured is placed on the corner mirror and can be measured with different probe systems. The high precision of the machine can be attributed to several factors. The most important is the accuracy of the interferometric measuring systems. Starting with a short description of NMM-1 and an improved equation for length calculation, this paper describes a small detail of the measurement uncertainty analysis for a displacement measurement using two positions of the measuring mirror. The overall 3D uncertainty for measurements carried out with the machine depends on the machine itself and the probe system in use as well as the specific measuring task. In particular, this paper discusses only the influence of the interference signal demodulation for homodyne interferometers.