Formation of plano-convex micro-lens array in fused silica glass using   CO2 laser assisted reshaping technique
  We report on fabricating high-fill-factor plano-convex spherical and square micro-lens arrays on fused silica glass surface using CO2 laser assisted reshaping technique. Initially, periodic micro-pillars have been encoded on the glass surface by means of a femtosecond laser beam. Afterwards, the micro-pillars are polished several times by irradiating a CO2 laser beam on top of the micro-pillars. Consequently, spherical micro-lens array with micro-lens size of 50 um x 50 um and square micro-lens array with micro-lens size of 100 um x 100 um are formed on fused silica glass surface. We also study the intensity distribution of light passed through the spherical micro-lens array engraved glass sample. The simulation result shows that, the focal length of the spherical micro-lens array is 35 um. Furthermore, we investigate the optical properties of the micro-lens array engraved glass samples. The proposed CO2 laser based reshaping technique is simple and fast that shows promises in fabrication arrays of smooth micro-lenses in various transparent materials. 
Ik-Bu Sohn, Hun-Kook Choi, Dongyoon Yoo, Young-Chul Noh, Md. Shamim   Ahsan, Jae-Hee Sung, and Seong-Ku Lee
physics.optics