Mold Stamping of Optical Glasses using Superhydrophobic Surface Die by Micro/Nanotexturing

Abstract

Femtosecond laser machining was utilized to form the micro/nanotextures on mold material to transform a hydrophilic surface to a superhydrophobic one. The mold surface was segmented into unit cells by laser microtexturing; at the same time, each segment was nanotextured to have nanoscaled ripples by laser-induced periodic surface structuring (LIPSS). The micro/nano-textured SUS420 molds were hydrophobic with high contact angles and repellency. Each mold was fixed into a cassette die set for mold stamping of the phosphate glass specimens. The induction heating unit was utilized for this hot mold stamping at above the glass transition temperature. The static contact angle of the optical glass surface increased two fold from 56° to 114°.