Nowadays, although most of optical design processes have been automated with the acid of computer software, there remains the fundamental question of "how to generate the initial optical configuration to the one dealt with by the computer". Only techniques based on the aberration theory will be able to answer this question. This book is intended for the reader to study aberration theory beginning with its derivation and ending in its various techniques which can be applied effectively to practical design problems. These techniques are illustrated together with various kinds of actual examples.