Small-size microlens characterization by multiwavelength high-resolution interference microscopy

Microlenses are widely studied in two main areas: fabrication and characterization. Nowadays, characterization draws more attention because it is difficult to apply test techniques to microlenses that are used for conventional optical systems. Especially, small microlenses on a substrate are difficult to characterize because their back focus often stays in the substrate. Here we propose immersion high-resolution interference microscopy to characterize small-size microlenses at three visible wavelengths. Test results for 20-?m-diameter microlenses are presented and discussed. We cover not only standard characterizations like wavefront investigations but also experiments of actual focus properties and chromatic behaviors.