Spherical and non-spherical high fill-factor microlens arrays fabricated by polymer coating on isotropically etched quartz

Various shapes of microlens arrays (MLAs) were developed by utilizing polymer coating on etched quartz substrates. Spherical and non-spherical plano-concave curvatures were realized via isotropic wet etching of quartz in buffered oxide etchant (BOE), based on diverse design parameters and calculated etching times. The fabricated curvatures showed a high fill-factor and uniform elements in the array. By coating a higher refractive index polymer on the etched quartz, the illuminated light was well focused at the focal plane forming a micronscale light spot array. The experimental focal length was increased from 39.8 to 49.6 μm, as the shape of microlens was flattened. These results well correspond to those obtained from an optical simulation.