Glasses election to provide aplanatic cemented doublets

Abstract

In general, the correction of cemented doublets is based on the convergence condition and the correction of spherical and chromatic aberrations. This can be achieved by a suitable assignation of values to the lenses radii. Moreover, if during the correction process a change of glass is introduced, it is possible for another aberration to be in tolerance. The result is a two lens system which, in spite of its simplicity, is free of many aberrations. The current presentation describes a method to obtain aplanatic cemented doublets, with the spherical, coma, and chromatic aberrations in tolerance, by an appropriate selection of glasses before the project. Some maps of glasses with lines which provide this election are presented. These lines are valid for both telescope and microscope objectives. Besides, with this method it is possible to easily project aplanatic cemented doublets with a residual value of the spherical aberration. Finally, it is also shown that certain combinations of glasses are impossible to be corrected simultaneously of spherical and chromatic aberrations.