Measurement of nanoscale displacements using a Mirau white-light interference microscope and an inclined flat surface

Measuring nanoscale displacement is crucial for optical nanometrology. We report an approach to measure vertical nanoscale movements using a Mirau white-light interference microscope. Our technique is different compared with conventional methods. The vertical nanoscale displacement is determined by analyzing interference patterns in the x direction (instead of common z direction) via an inclined surface, which reduces the processing time. By analyzing the obtained interference images, which appear at two successive positions of an inclined flat surface, the maxima of interference signals and the tilt angle are determined. From these two parameters, the displacement is calculated. Using this approach, the transition of several tens of nanometers can be measured. We experimentally investigate the movement of a piezoelectric transducer and the obtained result agrees well with that provided by the manufacturer. Our finding is highly beneficial for optical measurements and surface topography. © 2019 Society of Photo-Optical Instrumentation Engineers (SPIE).