This volume is based on Michael Kidger's short course for SPIE entitled âFundamental Optical Design.â It reviews basic geometrical optics and third-order aberration theory, using the nomenclature and sign conventions of the Optical Design Group at Imperial College in the 1960s given in W.T. Welford's book, Aberrations of Optical Systems.
Michael's courses for SPIE were abbreviated forms of workshops that he taught for Kidger Optics. In these short courses, Michael concentrated on the application of this theory to the design of a variety of simple optical systems, with students spending about half of the course time working on these lenses with Michael's optical design code, SIGMA, under his supervision. This book attempts to re-create, for the reader, the teaching style and practical work that made these courses so popular with students all around the world. The design examples include prescriptions and aberration data generated by SIGMA, although the interested reader will find sufficient data to further explore the designs with any available optical design software.
With the advent of the PC in the 1980s, such software has become much more accessible to engineers and scientists without formal training in optics. Michael's short courses were aimed at such newcomers to what can seem, at first, a very daunting field. He always emphasized the need to understand why a particular lens works (or, more commonly, does not work!), rather than to blindly hope that the optimization code will find a miraculous, practical solution. In fact, the earlier Imperial College courses on optical design did not encourage access to an optimization program (in the 1960s and 1970s, residing on mainframe computers) until well after the student had a thorough understanding of geometrical optics and third-order aberration theory. This more academic approach, as part of a master's course in applied optics, encouraged a certain intangible âfeelâ for the subject that had the potential to develop into a more intuitive approach as experience was gained with a wider variety of optical systems, some of which might be novel or innovative.
In spite of the enormous improvements in computing power, optical design remains a discipline that is best developed in apprenticeship to a master practitioner. Traditionally, this takes years, but Michael gave many students a brief taste of this mysterious process of osmosis for a few days or hours. In the fast-paced modern world, this is becoming increasingly rare and precious, and it is hoped that this book at least provides a glimpse of it for posterity.
One of the reasons optical design is not easily learned from a textbook is that, in many cases, it is a necessary but not sufficient condition that the third-order aberrations are correctable. When fifth- and higher-order aberrations dominate, as they do at the larger apertures and field sizes often required, analytical dissection of the problem starts to fail, and optimization codes, experience and intuition become the designer's principal âtools of the trade.â In the commercial world, there is also the need to find a design that is manufacturable, often with conflicting requirements of low cost and high performance. A second volume, Intermediate Optical Design, will explore some of these issuesâapplied to more complex designsâbut the intermediate material will remain firmly grounded in the foundations of this first volume.
Most of the material in these volumes originates either directly from Michael's course notes, or from the unfinished book that he was working on. The editing process has included, for completeness, the addition of some material, while at the same time trying to retain Michael's original intent and style. In the first volume, this includes a brief discussion of pupil aberrations, some additional visual optical designs, as well as some catadioptric astronomical telescopes. Our hope is that Michael would be pleased with the result!
David M. Williamson
© 2002 Society of Photo-Optical Instrumentation Engineers