Glass has this too. it's why achromats and apochromats were developed (using rather clever ideas like pairing two different types of glass, which cancel each o

Glass has this too. it's why achromats and apochromats were developed (using rather clever ideas like pairing two different types of glass, which cancel each other's dispersions. All the physical explanations I've seen invoke the EM equations and quantum mechanics to explain it (and I don't understand it well enough to translate).