The Center for Freeform Optics
An Industry/University Cooperative Research Center

Diamond Milling of an Alvarez Lens in Germanium

Diamond milling of an Alvarez lens in germanium Diamond milling of an Alvarez lens in germanium Diamond milling of an Alvarez lens in germanium

Matt Davies and Thomas Suleski published a paper, ‘Diamond milling of an Alvarez lens in germanium,’ in Precision Engineering.

Abstract: Single crystal diamond milling of optical materials opens up new design degrees-of-freedom for optical engineers. However, parameters for milling of many optical materials have not been investigated, under- stood, or documented. This paper focuses on the milling of germanium to fabricate a freeform “Alvarez lens” in the mid-wave infrared (MWIR). While the design concepts for such optical systems have been known for decades, implementation has been limited due to difficulty in manufacturing the freeform surfaces. Ultra-precision, multi-axis machining centers can manufacture these surfaces through single crystal diamond milling. A battery of high speed diamond milling tests was performed in germanium to develop the parameters for machining the Alvarez components. Near-surface crystal quality and residual stress measurements using confocal Raman spectroscopy are reported, along with representative test results of the functioning optical system.

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Spring 2014