Manufacture of microlens arrays based on contactless embossing

WANG Yingchun, XIE Dan, ZHANG Honghai
(School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074, China)

Abstract: In order to reduce the requirement of the molding tool used by hot embossing for fabricating microlens arrays, the method of fabricating microlens arrays by contactless embossing was proposed. An independently developed nanoimprint machine and a stainless molding tool manufactured by photolithography with throughholes were used to fabricate microlens arrays on PMMA sheet. Influences of the temperature, the applied pressure and the embossing time on the focus of the microlenses were analyzed. The experimental results show that microlens arrays with good surface features and high position precision can be fabricated by contactless embossing. The optimum imprint temperature is 140℃ to 180℃, the optimum temperature for demoulding is 80℃, and the best applied pressure is 1 500 Pa to 3 500 Pa. Meanwhile, vacuum support is unnecessary when using the molding tool with throughholes, which can reduce the requirement of the environment.
Key words: microlens arrays; contactless embossing; photolithgraphy; throughholes