The mechanics of milling of germanium for IR applications

Freeform germanium optics produced by single crystal diamond milling are important for infrared (IR) imaging applications. However the mechanics of interrupted cutting of germanium is not fully understood. This paper presents new findings from cutting experiments including: (1) uninterrupted orthogonal cutting and (2) interrupted flycutting of germanium. Forces are measured and the cutting mechanics are correlated with surface and subsurface measurements performed with: (1) atomic force microscopy, (2) confocal Raman spectroscopy, and (3) channeling Rutherford backscattering spectrometry. These fundamental results guide parameter choice for more complex freeform ball milling of optics for IR applications ranging from surveillance to medical imaging.