A condition for achromatism of three lenses

Abstract

In this paper is given an account of an attempt at obtaining a general condition for the constancy of power for all wave lengths, in other words, total achromatism of a system of three separated lenses, in terms of Hartmann constants. The solution of the general equation by making the Hartmann constants a/Sub/1, a/Sub/2 and a/Sub/3 equal to unity, is naturally the simplest and the condition of achromatism arrived at is shown to be that of three lenses in contact.