UV induced controllable volume growth in hybrid sol-gel glass for fabrication of a refractive microlens by use of a grayscale mask

We report a simple method for forming surface corrugation of microlenses based on a volume growth effect of sol-gel glass. The volume growth effect was fully calibrated with a high-energy beam-sensitive grayscale mask, where the amount of growth was determined as a function of electron-beam-induced optical densities in the mask. This technique provides an excellent surface smoothness compared with other development based fabrication techniques. For example, a refractive microlens with a diameter of 140 microm and a sag height of 2.13 microm was demonstrated.