Study of ultra-precision diamond turning of a microlens array with a fast tool servo system

A Microlens array is a critical component for optimizing display functions. With the increasing usage of display systems in photonic products nowadays, more attention is being paid to the research and development of fabrication technology for microlens arrays. Ultra-precision machining with a fast tool servo (FTS) is one of the leading methodologies for fabrication of high-quality optical micro structural surfaces. FTS is an independently operated positioning device, which provides an indispensable solution for machining optical microstructures with sub-micrometer form accuracy and nanometric surface finish, without the need for any subsequent post processing. The surface quality of an FTS machined surface depends largely on the selection of cutting conditions. However, the achievement of ultra-precision surface finishing depends greatly on the experience and skill of the machine operators. Determination of optimal cutting conditions can stabilize the quality of the fabricated microlens array. In this paper, the effect of cutting conditions such as depth of cut, feed rate, spindle speed and surface speed are investigated; and optimal surface roughness and surface profiles in ultra-precision machining with FTS can be observed.