Hot mold stamping of optical plastics and glasses with transcription of super-hydrophobic surfaces

The oxide-glass lens as well as metallic-glass, optical elements were a typical targeting product to have their surface hydro-phobic or super-hydrophobic for well-defined water repellency. The micro- or nano-texturing processes were developed with use of the femto-second laser machining to control the surface state from hydrophilic to hydrophobic conditions. The femto-second laser processing had possibility to physically control the contact angle up to θ > 150 ^o . Under this laser induced periodic surface structuring, the ripples with high spatial frequencies were formed on the micro-textured surface by the interference of the incident and reflected laser lights with the scattered or diffracted light near the surface. AISI420 mold was prepared as a die substrate to form the super-hydrophobic surface by the femto-second laser nano-/micro texturing with the tailored design of laser induced periodic surface structuring. This mold was set-up into the cassette die set for hot mold stamping. The mold was directly heated up to the forming temperature above the glass-transition temperature by the high frequency induction heating. The original static contact angle was doubled from 60 ^o to 113 ^o by this hot mold stamping.