> it becomes transparent when the grain of the sand is half the wavelength of the light
That seemed to have intriguing potential as an educational story.
But it felt odd. Briefly googling suggests optical polishing compound grains are almost all 1+ um.[1] But maybe that <1 um tail is key? This[2] shows larger grains, with a tail growing over hours. But lens roughness is already at ~1 nm without the tail, and the growing tail only slightly improves that. On the other hand, perhaps sub-um fragments from the hydrated damaged surface are being entrained by the lap pitch or wax or slurry? Don't know. But it seems a half-lambda grain-size story has difficulties.
Oh well. :) Thank you for this. I wish I could find an online community interested in crafting improved stories for teaching science and engineering. My in-person ones... covided. :/
Sorry, I don't recall the specific details of glass polishing in this story; probably the datum I said does not make sense.
You can find this inspiring story, and many, many others, on Feynman lectures on physics. I'm sure the stories as written by Feynman will be exact and true.
That seemed to have intriguing potential as an educational story.
But it felt odd. Briefly googling suggests optical polishing compound grains are almost all 1+ um.[1] But maybe that <1 um tail is key? This[2] shows larger grains, with a tail growing over hours. But lens roughness is already at ~1 nm without the tail, and the growing tail only slightly improves that. On the other hand, perhaps sub-um fragments from the hydrated damaged surface are being entrained by the lap pitch or wax or slurry? Don't know. But it seems a half-lambda grain-size story has difficulties.
Oh well. :) Thank you for this. I wish I could find an online community interested in crafting improved stories for teaching science and engineering. My in-person ones... covided. :/
[1] eg, for plastic lenses, https://secureservercdn.net/45.40.144.200/i1r.357.myftpuploa... from http://www.gkci.com/opthalmic/ready-to-use-plastic-lens-poli... . [2] page 7 of https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-16-14-1...