It has been four years since the publication of the ?rst edition of this book. During these four years optical imaging has advanced considerably. Nevertheless, when we were asked to compile a second edition of this book the ?rst question we asked was: are there any topics that were missed out from the ?rst edition? Even though there are a fairly large number of subjects that we could potentially have considered it was decided to extend the book by two new chapters. The ?rst one is on the use of di?ractive optical elements in high quality objective lenses by Drs Brunner and Dobschal from Carl...