Assessing microlens quality based on 3D irradiance measurement at the focal spot area

During the fabrication process of microlenses, characterization is essential for two purposes: evaluate the optical quality of the element and provide surface information feedback for process optimization. However, no technique can fulfill these two objectives at the same time. Interferometry is used for quality evaluation and optical profilometry for process optimization. In order to address this problem, we propose to use a high resolution interference microscope to characterize microlenses. The focusing capacity can be directly measured by recording the field near the focal spot at different wavelengths. Information about the microlens surface can also be retrieved. All this is illustrated for the front focus of a fused-silica microlens.