Nanometric cutting of single crystal silicon for large-diameter aspheric optical element

A new method for diamond turning aspheric surfaces on hard brittle materials, termed the straight-line enveloping method (SLEM), is proposed. In this method, the aspheric surface is generated using a straight-nosed diamond tool on a three-axis simultaneous control ultra-precision machine tool. This tool geometry enables thinning of the chip in the nanometric range at the same time provides significant width to undeformed chip thickness ratio to ensure plane strain conditions. The cutting experiment of a large single crystal silicon aspheric lens is described. It is demonstrated that the proposed method significantly improves machining efficiency, accuracy and lowers tool wear.