Is it possible to "dope" glass to change it's refractive index? [closed]








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For many purposes, like in the making of achromatic lens combinations, we need transparent media of different refractive indices. Let's assume I want a transparent medium of refractive index of 1.4, how would I go about getting such a material? Can I "dope" it by dissolve some impurities into molten glass mixture and then solidify it later? How would I choose my impurity to add? How do I calculate how much to add?




Glass doesn't crystallize at all, that's the point. Consequently, unlike crystalline materials, it doesn't have fixed composition. In a way, it can be said that glass *consists of* impurities. And yes, of course, you may change its composition this way or that, so as to tune the refractive index to your purposes.


Further reading: [crown glass](https://en.wikipedia.org/wiki/Crown_glass_(optics)), [flint glass](https://en.wikipedia.org/wiki/Flint_glass).


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Well, yes. That is how they make lenses. If you don't know what impurity to add you can fiddle with the density, which - usually - changes the index of refraction. So you can take some $\ce{PbO}$ or $\ce{B2O3}$ and add to your $\ce{SiO2}$ to get different average densities. Higher density = (probably) higher index. But this is not a 1:1 relation, it is a very noisy correlation for glasses and minerals. The correlation is very good for liquids or mixtures of miscible solvents - and then it is called the [Gladstone-Dale Relation](https://en.wikipedia.org/wiki/Gladstone%E2%80%93Dale_relation) 


This used to be a "known" relation and referred to in science but it has fallen out of favor due to other, more explaining relations between more sensible parameters. It is a bit 1700-ish to promote a direct relationship between physical density and optical parameters, especially when you have to disregard the wave nature of photons. The "modern" ones relate to polarizability and permittance - which makes more sense.


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