Light homogenizing elements are described. The light homogenizing elements include lens arrays with corrective features designed to improve the uniformity of light fields produced by optical sources. The corrective features include masks placed at selected positions of selected lenslets in a lens array. The corrective features block or reduce the transmission of light through the lens array at the selected position to correct for spatial or angular non-uniformities in a light field produced by an optical source. Illumination systems that include a corrected lens array coupled to a light source produce highly uniform light fields. Applications include microlithography.