Why can't we get synthetic sapphire eyeglasses? Abbe number 72.2 (!!!!) and high index of refraction.
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Replying to @RichFelker @bofh453
1) fragile? 2) I bet milling it to size is going to be a real pain at an ophtalmologist's shop
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Replying to @whitequark @RichFelker
1) Um. You've worked with synthetic sapphire before, right? http://www.mt-berlin.com/frames_cryst/descriptions/sapphire.htm … vs http://www.mt-berlin.com/frames_cryst/descriptions/quartz%20.htm …
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You're looking at Mohs hardness 9.0, Young's/Bulk/Shear moduli 345/240/145 (all GPa), 400MPa tensile strength. No glass is that strong.
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Ironically this makes your 2nd point much stronger, since I imagine actually milling/cutting/making adjustments to Sapphire is much harder.
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But honestly I think the main reason is even simpler: cost. Glass is cheap as hell.
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Replying to @bofh453 @whitequark
Glass lenses are actually rather expensive compared to CR39 which is almost as good (within 1.0 Abbe value diff) & better at blocking UV.
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But people pay big $ for the awful polycarbonate, etc. lenses all the time, with *awful* chromatic aberration. I'd pay 5x that for sapphire.
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Replying to @RichFelker @bofh453
wait, PC is awful? I like how indestructible it is, and it lets me use nearly nonexistently thin frames
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Yes, Abbe value of 30.
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