Optical properties of microlenses fabricated using hydrophobic effects and polymer-jet-printing technology

Abstract

We describe high-precision microlenses with excellent optical characteristics. The lenses are formed precisely at desired locations on a wafer using a polymer-jet system in which hydrophobic effects define the lens diameter and surface tension creates a high-quality optical surface. To make the lenses, we defined hydrophilic circular regions at desired locations using photolithography to pattern a 0.2-pm thick Teflon (hydrophobic) layer on a quartz substrate, as shown in Figures 1 and 2. Then, using a polymer-microjet printing system (Figure 3), we dispense an exact amount of UV-curable polymer within hydrophilic circles to obtain microlenses having desired optical properties [ 13. Figure 4 shows that adjusting the volume of the UV-curable optical epoxy within a hydrophilic circle of a given diameter changes the curvature of the microlens. The step resolution of the microlens volume is determined by the average droplet size (~25pL) of the polymer-jet print head. This hybrid method enables us to define the locations and diameters of microlenses with a ±1 μm precision as well as to control the curvatures of the microlenses accurately.