| Direct drive inertial fusion energy (IFE) requires the injection, tracking, and engagement (illumination with high-powered lasers) of reflective spherical shells (targets) in order to produce fusion ignition and energy gain. Targets need to be tracked with 10-mum precision for this method of IFE to succeed. In this paper, one method for tracking targets is investigated, including a brief overview of existing tracking technology, analytical investigation of precision and design, and the results of a small-scale laboratory demonstration. This homodyne displacement measuring interferometer technique is labeled "fringe counting," and although the laboratory demonstration had mixed results, fringe counting may be capable of providing 10-micron precision measurements of target motion along the direction of travel for IFE.;Robustness of the system is a serious concern. Suggestions for future improvement are provided. The conclusion includes an initial design for a full scale IFE fringe count system that incorporates many of the suggested improvements from this thesis.;In addition to the main body material, several appendices are included. One examines potential for larger-scale injection/tracking demonstrations; another examines the Cat's eye retro-reflector and its invaluable use as an alignment tool for interferometers. And finally, a heterodyne system based on the concept of Zeeman splitting is investigated. |
