Highly divergent homogenizers for UV and deep UV

Abstract

For many applications such as lithography and material processing, the hsaping and homogenization of a UV or Deep UV source needed. Often the divergence angle needed is fairly large ($GTR5 degree(s)half angle). This can be very difficult using diffractive homogenizers, especially when the divergence needed approaches 10 degree(s)half angle. Presented in this paper is a new technique that has the ability to homogenize and shape a deep UV source by more than 10 degree(s)half angle. This technique uses a deep ($GTR10 waves) microstructure that bends the light by the required amount. The fabrication of this microstructure is practical only with gray scale or analog lithography. With gray scale lithography, complicated smooth surface relief structures are possible in one lithography step. Older fabrication methods have good design freedom in the two dimensions associated with the plane of the wafer or optic but have limited design freedom in the dimension of the microstructure depth. Gray scale lithography opens up this dimension of the micro optic as a design freedom making higher performance micro optics possible and economical. Design, fabrication, modeling and test results will be discussed.