Improvements on the uniformity of large-area microlens arrays in Fused Silica.

The uniformity of large microlens arrays in Fused Silica is governed by the production process. It comprises photolithographic patterning of a spin-coated layer of photoresist on a 200mm wafer with a molten resist reflow process and subsequent dry etching. By investigating systematic influences throughout the production process we show how to steer the lens production process with a single degree of freedom to improve the uniformity of the final microlens array. To enable this we describe the optical performance of microlenses with only one parameter: the principal aberration component. It is the result of principal component analysis of the chosen optical merit function. We present the case of manufactured microlens arrays with element sizes >100 mm × 100 mm where uniformity was improved by a factor of 2.