Laser assisted fabrication of micro-lens array and characterization of their beam shaping property

This paper demonstrates the formation of high-fill-factor plano-convex cylindrical and dome-type micro-lens arrays on fused silica glass surface using CO2 laser assisted reshaping technique. Cylindrical micro-lens array is fabricated by polishing the femtosecond laser engraved linear micro-gratings by a CO2 laser beam. Initially, a femtosecond laser beam has been irradiated on the surface of the fused silica glass samples to fabricate periodic micro-gratings on the glass surface. Afterwards, these micro-gratings encoded glass samples are polished several times by a CO2 laser beam. As a result, plano-convex cylindrical micro-lens arrays with the lens period varying from 20 mu m to 50 mu m are developed on the glass surface. Similarly, dome-type micro-lens array is achieved by femtosecond laser assisted fabrication of periodic micro-pillars followed by several times CO2 laser polishing. We report the formation of a large variety of dome-shape micro-lens array with lens size varying from 20 mu m x 20 mu m to 50 mu m x 50 mu m. The fabricated micro-lenses show great consistency in size and shape throughout the sample area. We also investigate the intensity distribution of light passed through the micro-lens engraved glass samples. Using the dome-type micro-lens array engraved glass samples, a Gaussian laser beam has been converted to a flat-top laser beam for selective patterning of a thin indium-tin-oxide coating from fused silica glass surface.