Bulk metallic glass mold for high volume fabrication of micro optics

Suitable mold materials are critical for successful high volume replication of micro optical components. As one of the emerging new materials, bulk metallic glass (BMG) can serve as high-quality mold material to overcome the existing changelings with current mold materials. Zr-based BMG does not have the intrinsic structural defects and can be precisely formed into desired shape at elevated temperature. Therefore, the unique combination of good forming ability at elevated temperature and sufficient strength at working temperature make it perfect as high quality mold material for optics fabrication. This paper investigated the fabrication and use of BMG mold inserts to create micro optics on polymethylmethacrylate (PMMA) substrate. BMG mold inserts were replicated from a fused silica master mold using precision glass molding techniques. The molded BMG inserts with optical features were used next as secondary molds to manufacture of polymer micro optics. High volume production methods, i.e., hot embossing and injection molding, are investigated. In order to evaluate the performance of BMG inserts, the geometry of the gratings on PMMA part were verified with fused silica master mold and BMG inserts using a non-contact profilometer. In addition, an instrument designed to measure surface scattering was used to measure the light distribution from the gratings. By using this process, high performance and BMG mold inserts for hot embossing and injection molding can be prepared cost-effectively for high volume production of plastic micro optical components.