Manufacture of Infrared Optics in Brittle Materials
1 online resource (138 pages) : PDF
University of North Carolina at Charlotte
Infrared optics are manufactured for many different applications including: thermal imaging, surveillance, night vision, medical, laser machining, laser surgery, etc. Most infrared transparent materials are hard, brittle, or both. Unless special conditions are generated, diamond machining will lead to surfaces dominated by brittle fracture. The overall purpose of this dissertation is to further the state-of-the-art of infrared optics manufacturing. The first piece of this dissertation is to explore the ductile-brittle behavior of two different infrared materials: germanium and IRG 26 (a chalcogenide glass by Schott). These two materials are very useful IR materials: germanium for its high index of refraction and IRG 26 for its low glass transition temperature allowing for easy molding. The cutting mechanics for these materials was experimentally observed during a series of different cutting operations: face turning, planing/ruling, orthogonal turning, and ball milling. Cutting and thrust forces were measured and analyzed for the force coefficients as a function of the cutting parameters. The cutting force coefficients were found to have a significant drop as the cutting mechanics became increasingly brittle with higher chip thicknesses. The reduced cutting forces at more aggressive parameters could lead to a means of rapid prototyping of IR optics. The second piece of this dissertation is to outline a procedure developed to correct tool errors of a diamond ball mill. Two dominate tool shape errors of a ball mill are diamond position and cutting edge irregularity. An artifact based procedure was used to imprint the tool errors on a measureable part.
BRITTLE MATERIALSDIAMOND MILLINGDIAMOND TURNINGFORCE PREDICTIONFREEFORMINFRARED OPTICS
Evans, ChristopherSuleski, ThomasSchmitz, TonyDavies, Angela
Thesis (Ph.D.)--University of North Carolina at Charlotte, 2015.
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