On the Choice of Glasses for Cemented Achromatic Aplanatic Doublets

Abstract

It is shown that the types of glass given by tables for thin, low aperture telescope objectives of the "crown leading" doublet form are also those most suitable for thick, high aperture systems. The maximum focal lengths and the tolerances permissible in glass properties are given for each aperture, and the variation of these properties is considered when the thickness or wavelength of correction is changed, or the objective used with prisms.