Proceedings PaperIn Process Test Procedures For A Diamond Turned Germanium Aspheric Lens Of High Quality
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Numerically controlled single point diamond turning is an important alternative manufacturing technology to conventional polishing for the manufacture of infra-red optics. The technology is capable of creating high quality aspheric surfaces on materials such as germanium, silicon zinc sulphide, and zinc selenide. It is essential that in-process optical test methods are applied consistent with a logical sequence of manufacturing steps which can be tested for appropriate accuracy at each stage. Certain machines are suited to machine based optical test using laser interferometric methods. Test methods are described which allow aspheric lenses to be created. Results are presented for a 50 mm F/2 germanium lens which outline the in-process tests employed and are supported by IR performance data for phasefront aberration and M.T.F. The optical performance agrees well with the design and represents current state of art diamond machining.