Silicons are used in both wafer fabrication and infrared optics. Direc
t machining of silicon single crystal was carried out on a precision l
athe equipped with an air spindle to a finish of 2.86 nm rms roughness
. The success of the turning process depends on optimizing the machini
ng parameters such as feed rate, depth of cut, tool rake angles, the c
utting lubricants and the crystallographic orientation of the crystal
being cut. It is shown that the commercial production of an optical su
rface on brittle materials is made possible by single point diamond tu
rning. (C) 1998 Elsevier Science S.A.