Design of a three Degrees of Freedom planar precision stage using a single Position Sensitive Detector

Abstract

This thesis presents the design and implementation of a precision stage equipped with novel sensing and actuation concepts. The stage is considered among the first stages capable of providing a full rotation as well as planar translations with only one moving part and one sensor, namely a Position Sensitive Detector. This affordable sensor produces a signal which is proportional to the location of the centroid of the incident light beam. Instead of measuring the position of one light beam, as the conventional use of this sensor implies, three light beams are sequentially projected on the PSD. A sensing algorithm has been developed for sampling and converting these three sensor signals into planar position data: x, y and theta. The stage is intended for use in the field of digital microscopy where it will enable the user to view the sample from all sides without manually relocating the specimen. The underlying mechanical design, sensor technology, electromagnetic modeling and real-time control of such a high-precision planar stage are presented together with the final performance specifications.