Fabrication of refractive microlens array by etching ammonium dichromate gelatin (ADG) with enzyme
Yao J., Gao F., Gao F., Zhang Y., Su J., Guo Y., Cui Z.
A new method has been developed to fabricate refractive microlens by etching ammonium dichromate gelatin (ADG) with enzyme solution. Unlike previous methods which are used to fabricate refractive microlens with photoresist, the process of fabricating microlens by etching ADG with enzyme solution doesn't require the use of expensive equipment, and it isn't sophisticated and time consuming. The light exposes ADG through a high contrast binary mask, then the exposed parts of ADG generate cross-linking reaction. Usually, the relief achieved by water developing is very shallow (<1 um) when nonpre-harden gelatin is used, so we compound a certain concentration enzyme solution as the developing agent to develop ADG. At a certain temperature, the biochemical reaction occurs between ADG and enzyme solution, and because of surface tension, ADG turns to spherical structure after developing. The optimum technique parameters of this process are presented. Results are presented for experiments and evaluated by profile meter and interference microscope.