Microlens fabrication by the modified LIGA process

A microlens or microlenses array has been fabricated by a novel fabrication technology which is based upon a deep X-ray exposure and a thermal treatment of a resist, usually PMMA. The fabrication technology is very simple and produces the microlenses array as well as the microlens which has good surface roughness less than I nm. Molecular weight and glass transition temperature of PMMA is reduced when it is exposed to the deep X-ray. The microlens is produced through the effect of surface tension and reflow by applying the thermal treatment on the irradiated PMMA. A configuration of the microlens is determined by parameters such as absorbed X-ray dose on PMMA, heating temperature, and heating time in the thermal treatment. Diameters of the produced microlens range from 30 /spl mu/m to 1500 /spl mu/m and their heights vary between 10 /spl mu/m and 25 /spl mu/m.