Manufacturing of Glass Diffractive Optical Elements by Use of Precision Compression Molding Process

Recent advances in compression molding process offer a potential high volume precision net shape fabrication method for micro and diffractive glass optical elements. In this research, glass diffractive optical elements with lateral features in the order of 2 μm and a vertical height of about 500 nm were fabricated using glassy carbon molds and BK-7 optical glass material. Glassy carbon molds used in this research were fabricated with traditional cleanroom lithography and reactive ion etching process. Compression mold process was performed to duplicate the diffractive structures onto optical glass surface. Molded glass diffractive elements were studied using an atomic force microscope and a Veeco optical profilometer to evaluate the accuracy of replication and the capacity of the molding process. Different molding process parameters were tested to improve the molding process. The experimental results showed that the compression molding process is an effective alternative fabricating method for high volume, net shape and low cost glass diffractive optical elements.