Precision Glass Molding of Micro Fresnel Lens

Experimental Study on Molding Characteristics with Molding Conditions and Feasibility Study

Abstract

This paper deals with the precision glass molding of micro fresnel lens with some micro grooves. Fresnel lenses are useful for the next generation type of optical devices because of its thin structure and excellent optical characteristics. In the conventional machining method, the lens materials were restricted to plastics, because the cutting tool was a single crystal diamond and the molding die material was restricted to a soft metal such as copper or electroless deposited nickel-phosphorous (Ni-P) alloy. In this paper, feasibility study of micro fresnel glass lens was carried out. In the glass molding experiments, the WC (tungsten carbide) molding dies of fresnel shape were used and the dies were ground by using the proposed grinding method with vertically controlled grinding spindle and the disk type wheel of knife edged shape. Then micro glass fresnel lenses were pressed in trial and the optimum press load and press temperature were studied experimentally. The experimental results show that a form accuracy of about 0.3 μm P-V and a smooth surface were obtained and it is clarified that this proposed molding method is useful.