Method for forming a tool for molding microlens arrays

摘要

A method for fabricating a mold tool for molding optical elements is taught which comprises heating a mold tool blank made from a vitreous material to a temperature above the glass transition temperature of the vitreous material; generating an axial viscosity gradient in the mold tool blank; pressing a punch into an optical quality mold surface of the mold tool blank, the punch including a pressing surface with a predetermined geometry for forming an optical feature; cooling the mold tool blank to a temperature below the glass transition temperature of the material; and removing the punch from the mold tool blank thereby creating the optical feature in the optical quality mold surface. The axial viscosity gradient is achieved by creating an axial thermal gradient. Multiple optical features can be formed in the mold surface of the blank using a single punch such that the pressing, cooling and removing steps are repeated with the punch or the blank being translated to a different position between the last removing step and the next pressing step. In such manner, a high temperature glass mold tool can be formed which can be used to mold glass optical elements either individually or in arrays.