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.

A nanomeasuring machine based white light tilt scanning interferometer for large scale optical array structure measurement

“…As a foundation of our system, the NMM, developed in the Ilmenau University of Technology for surface measurement within a measuring volume of 25 mm  25 mm  5 mm [8] was used. Three commercial interferometers inside the NMM read the stage position in real time so that the positioning control loop can assure a movement resolution of 0.1 nm [9].…”

Modular Family of Sensors for a Nanopositioning and Nanomeasuring Machine

“…Therefore, the focus sensor was modified into an interference microscope ( Figure 5) (Kapusi et al 2007). The focus lens is replaced by a Mirau interferometer objective, and the monitoring microscope is now directly used for recording the measuring data by a controlled z-scan.…”

A Speed-Up Study for a Parallelized White Light Interferometry Preprocessing Algorithm on a Virtual Embedded Multiprocessor System

“…Forthis purpose, depending on the surface characteristics and the signal-to-noise ratio of the generated signals, different approaches have to be considered [Rob93]. Envelope demodulation serves also as adata reduction step, because only the interval around the center of the interference is relevant for the postprocessing [KM07], as can be seen in Figure 1. The center of interference signal itself can not be seen as the envelope'sp eak.…”

“…The white light interferometry scanning is av ersatile technology which provides ar eliable non-contact, 3D optical measurement of surface roughness in the nanometer range [KM07]. In the scanning device, which is usually aM ichelson interferometer equipped with ab roadband light source, the emitted white light beam is split into twos eparate beams.…”