Precision Grinding of Micro Fresnel Lens Molding Die - Feasibility Study on Precision Grinding of Tungsten Carbide -

摘要

This paper deals with the precision grinding of micro fresnel shape 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, a grinding system of 4-axes (X, Y, Z, C), and a new grinding method with vertically controlled grinding spindle and the disk type of wheel with a sharp edge were developed. In a feasibility study of the fresnel shape grinding with the developed system, the molding dies of tungsten carbida for glass lenses were ground in trial. The experimental results show that a form accuracy of about 0.1 μmP-V and surface roughness of about 10 nmRy were obtained and this new grinding system is useful.