Analytic optimization of Dyson optics.
A prototype of a 248-nm optical projection printer based on the unit magnification Dyson configuration was designed and built [J. Vac. Sci. Technol. 9, 3108 (1991)]. Iterative computer methods were used to optimize the geometry of the system to provide minimum aberrations over a given field. Here we present an alternative optimization procedure and use it to design a 193-nm system. This new procedure yields useful insights into the design process and allows us to see why modifications in geometry are required for optimum performance. An understanding of the trade-offs involved in the optimization allows us to suggest and evaluate future design changes.
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