White light interferometry in combination with a nanopositioning and nanomeasuring machine (NPMM)

Abstract

This article presents white light interferometry as a new application for the nanopositioning and nanomeasuring machine (NPMM). The NPMM was developed under the leadership of the Institute of Process Measurement and Sensor Technology at the Technische Universität Ilmenau (Germany) and allows highly exact dimensional and traceable positioning with a resolution of 0.1 nm within a volume of 25 mm x 25 mm x 5 mm. An application of white light interferometry was developed on the basis of these features which can utilize the device's very high precision and large effective range, which enables the stitching of partitioned results without overlapping measurements and expensive matching methods. In order to extract height data from the interferograms, a robust, precise and fast method using matched filters in the frequency domain has been put into practice. The filter templates are calculated according to a model function or are directly sampled from the light source power spectrum, which has been previously analyzed once. Thus, light sources with different spectral forms can be used.