CAD-based metrology of freeform microlens arrays, FMLAs

Freeform microlens arrays, FMLAs, have gathered considerable scientific and industrial interest in recent years due to their advantages compared to the more standard MLAs, based on rotationally symmetric optical units. However, they pose are challenging to design and manufacture. More specifically, the complex surface shapes involved, typically described by a large set of parameters and the large number of individual microstructures in each FMLA makes their quality control cumbersome. Surface profile measurements involve many data points, difficult to handle and optical functionality tests provide little insight into potential manufacturing deviations. Here we present and demonstrate CAD-based characterization and design for manufacturing methods that at- tempt to overcome these limitations. We also present two additional CAD-based tools that analyze FMLA designs from a manufacturing perspective that we have developed to support optical designers and manufacturers alike to identify critical parts in an early stage. Our algorithms can process several hundreds of individualized microstructures in a couple minutes.