New Fabrication Method of Plastic Micro-Lens Arrays for Researching on Compound Eyes of Insects

Abstract

To develop artificial compound eyes, sizes of element lenses of typical insects were actually investigated, and a new simple and low-cost method for fabricating plastic micro-lens arrays was developed. It was thought essential to research on artificial compound eyes that lens parameters were freely controllable by our minds. For this reason, a new easy and low-cost fabrication method had to be developed. In the new method, original molds of micro-lens arrays with concave profiles were formed lithographically in a thick resist film. The concave resist patterns were printed using a handmade 1/19 reduction projection exposure system by only one exposure. Using intentionally defocused exposure, curvature radiuses were controllable in a very wide range of 21-85 I¼m for the same transparent hexagon patterns with an inscribed circle diameter of 26.3 I¼m. It was also verified that the resist-mold patterns were faithfully replicated to epoxy resin. After pouring the liquid resin onto the silicon wafer chip with resist-mold patterns, hardened solid resin with micro-lens arrays was separated from the wafer chip by peeling off the wafer chip mechanically. It is promising to fabricate micro-lens arrays with aimed lens parameters although some more subjects should be cared from now on.