Teaching optics - On correction of chromatic aberration

The elementary theory of aberrations as well as the skill to design optical systems of desired characteristics belong to canon subjects of optics teaching. However, lecturing on aberrations theory is difficult from the didactic point of view and is little attractive to the students. Besides, when designing the optical systems some specialized computer programs are used, which more and more seemingly eliminates the necessity of studying the theory of aberrations. In spite of this opinion, some acquaintance with relevant problems of aberration correction seems to be unavoidable. The aim of the present paper is to facilitate the mastering of a necessary minimum knowledge in the field of chromatic aberration correction. The problem of chromatic correction has been illustrated by typical examples. Such optical systems as classical glass doublet, hybrid lens and triplet have been considered. Three main types of chromatism correction, Le, achromatic, apochromatic and superachromatic have been analysed. Also the spherochromatic aberration correction has been demonstrated.