Proceedings PaperFabrication of large calcium fluoride lenses
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Lenses made from the optical crystal, calcium fluoride, are required in spectrograph camera designs for many of today's astronomical telescopes. Often these cameras are of large aperture with lens diameters in the 12 inch to 15 inch range. This material is highly susceptible to mechanical and thermal shock, resulting in fracturing. Large calcium fluoride lenses, with their varying thickness profiles, require techniques and precautions in processing from raw material to a finished lens that aren't required with windows or small lenses. This paper describes techniques learned and used at the Lick Observatory Optical Lab that deal with working this delicate crystal and producing large finished lenses.