Fabrication of a random convex-lens-shaped microstructure using a laser ablation

A convex-lens-shaped microstructure with a diameter of 50 μm on a metallic mold substrate was fabricated in this paper. A laser ablation process, in which the laser beam was focused and irradiated on the metallic mold substrate in order to remove a part of the substrate, was used for that. The convex-lens-shaped microstructure has not been reported in any studies of microstructure using the laser ablation process. It was proposed that the unbalanced ablation and re-adherence of the melted particles was the processing mechanism of the convex lens shape. The convex-lens-shaped microstructure fabricated in this study is smaller than the focused spot. It was expected that the same convex-lens-shaped microstructure can be fabricated even if the focused spot size is increased, so long as the fluence of the laser can be maintained. Therefore, the method proposed in this paper will improve the low processing speed, which has been the problem of a laser ablation process. The fabricated convex-lens-shaped microstructure on the metallic substrate can be used as the mold for the micro lens.

► We fabricate a convex-lens-shaped microstructure with a diameter of 50 μm on a metallic mold substrate.
► We improve the fabrication speed of micro lens mold by using proposed technology.
► The various microstructures are fabricated by laser defocusing beam.