W.T (Imperial College, London, UK) Welford 
Aberrations of Optical Systems [PDF ebook] 

Although the subject of optical design as a branch of applied physics is over one hundred years old, the use of aberration theory has changed considerably. Aberrations of Optical Systems covers elementary optics and aberration theory of various optical systems, including the use of nonaxially symmetric systems and diffractive optical elements in complex designs, such as head-up displays and the increasing use of scanning systems with laser illumination. The book provides the complete range of mathematical tools, formulae, and derivations needed for understanding the process of optical design and for planning optical design programs. While the treatment is mainly based on geometrical optics, some excursions into physical optics are made, particularly in connection with the problems of optical tolerances.