Illumination systems for various industrial applications, e.g., in semiconductor industries and medical treatment techniques, require a specific and well-adapted intensity distribution with maximum efficiency, best achievable accuracy, and highest flexibility in the selection of the target light field. Additionally, for particular applications, all these aspects have to be fulfilled simultaneously for different wavelengths. In most of these situations, the challenging optical specifications are accompanied by the requirement of a cost-efficient fabrication technique, suitable at least for batch or small series production. In the present contribution, we first retrace the development steps and performance progress of micro-optical-based beam shaping setups. Secondly, we discuss the possibilities resulting from a combination of both refractive and diffractive optical characteristics. Especially, we show that a well-adapted combination of refractive and diffractive properties in a single element allows us to create achromatic diffusers with exceptional flexibility and high conversion efficiency.
To realize a well defined binary grating (for grating originals as well as grating masks), it is helpful to use a rectangular resist profile because ofthe importance ofthe fill factor. This can be achieved easier by e-beam writing than by holography. on the opposite, well-known handicaps of e-beam writing are large writing times and grating ghosts (caused e.g. by stitching errors). We fabricated chromium grating masks (period 500nm, size 100mm x 100mm) by an extremely fast and specialized e-beam direct writing process. The typical and critical parameters, like fill factor and wave front, were locally measured in the whole grating area. The paper will show the method of e-beam writing and the results of lateral grating quality. The remaining errors are separated in problems caused by the writing process and in problems related to resist technology and etching process.
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