What is this ISO 12123 - Optics and photonics — Specification of raw optical glass about?
ISO 12123 gives rules for the specification of raw optical glass. It serves as a complement to the ISO 10110 series, which provides rules specifying finished optical elements. Since raw optical glass can be quite different in shape and size from the optical elements, its specification also differs from that of optical elements.
ISO 12123 introduces definitions, reference formulae and data needed for calculating the deviation of the relative partial dispersion from the normal line. This quantity serves to value the suitability of optical glasses for colour aberration correction beyond achromatic correction of only two colours.