The optimization of fresnel zone plates for use in focused-beam measurement systems

Fresnel zone plates have been used as replacements for doubly-hyperbolic lenses in free-space, focused-beam systems to measure the electrical properties of materials [1]. These zone plates were designed using the traditional method for determining the profile of a zone plate, which is based on optical, ray-tracing principles [2]. In this work, a non-traditional, optimization-based design methodology featuring the genetic algorithm will be explored to determine if the performance of a zone plate can be improved for the focused-beam application. Results will be presented that compare the optimized design to the traditional zone plate and to a doubly- hyperbolic lens.