Single-point diamond turning of lead indium phosphate glass

The development of the ability to routinely ''machine'' glass materials to optical tolerances is highly desirable and, in particular, could provide new degrees of control over the precise shape of complex and unusual optical surfaces. Of particular interest in this regard is the formation of non-spherical shapes where there is a need to fabricate both inexpensive, low-precision optics as well as specialized high-precision aspheric components. This work describes the initial feasibility tests of the machining of a new type of glass, lead indium phosphate (LIP), a material which transmits from the visible to 2.8 mu m (for thin samples). Glossy surfaces were produced with a root-mean-square surface roughness of less than 100 nm (with 200 mu m filter). The results indicate that this approach offers the potential for producing high-quality aspheric optical shapes based on the use of LIP glass.