Optical Designer, Teacher
Michael Kidger was a man of superior scientific and technical talent who had a longing to do a job with a completeness and thoroughness that made it easy for others, including his students, to understand and follow. He had little concern for mundane reward, only the reward and satisfaction of knowing he had done his best. Michael's enthusiasm for optical design was kindled in his student years and continued to grow throughout his working life. He strongly believed that non-specialists could produce effective optical designs provided that the theoretical and practical tools were developed and presented to them in a coherent and unified way. He achieved this ambition through his pioneering activity in the development and application of software for optical design, through his instinctive 'touch' for extracting simple, comprehensible and useful rules from the mass of theoretical work that surrounds the subject, and through his teaching.

The Early Years
Michael John Kidger was born 6^th July 1937 in Birmingham, England. He was the only son of John and Lillian Kidger, who were both teachers. The family moved to Redditch, in Worcestershire, where Michael attended the local Grammar School (Redditch County High School). Such was Michael's academic ability that in his final school year he was awarded a Royal Scholarship to Imperial College, London, and also a County Major Scholarship from the County of Worcestershire, UK, where he lived.

Development as an Optical Designer
As an undergraduate Michael was influenced by Professor Walter Welford, who lectured in lens design at Imperial College, and who became the source of Michael's interest and enthusiasm for lens design. After graduation, Michael went on to take an MSc, and left Imperial College in 1960 to work with Rank Taylor Hobson in Leicester. At Rank he worked on a range of optical products, but particularly on zoom and fixed focus camera lenses. During this time on November 26^th 1960 at the church of St George, Redditch, he married Tina Emily Webb, whom he had known for many years.

In 1963 Michael returned to Imperial College and joined the Optical Design Group developing software for 'automatic lens design' under the leadership of Charles Wynne. The group refined a technique for damped least squares optimisation which has proved to be the most effective, robust and reliable way of reaching the optimum design. This technique is widely used in modern optical design software packages.

In 1971 he was awarded a PH.D for his thesis entitled: "The application of electronic computers to the design of optical systems, including aspheric lenses."

In the early 1970's, Michael quickly recognised the potential of desktop computers for optical design. He saw that instant availability, on-screen graphics and the inter-active capability would offer immeasurably greater freedom for experiment and innovation and that this would be the way forward. He led the development of a series of software packages that matched the rapidly increasing power of the desktops. Although the early machines were costly, limited in speed and limited in memory capacity, Michael showed that they could be used for effective optical design and had many advantages compared to the mainframe alternatives. It was his aim that the software should be easy-to-use and intuitive, should not require frequent reference to a manual (or Help files), and should only require the minimum of input from the user.

Michael recognised that the long history of optical design had engendered a mountain of theoretical work: originating in different countries, approaching optical design from different angles, and using different nomenclature and sign conventions. Much duplication and overlap existed. All this was daunting, and not very helpful, to students of optics. Michael being adept at selecting topics that would be useful in the mainstream of optical design, reducing the theory to the essentials, and re-writing the theory using a common nomenclature and sign convention, altered the academic environment for students of optical design. His students gained the advantage of learning practical optical design using theoretical and software tools written in a unified 'language'.

Optical design was revolutionised in the 1980's by the arrival of the IBM PC. At last, both software and hardware costs were affordable and optical design became a regular activity for many engineers and scientists. This new wave of designers far outnumbered the specialists creating an urgent need for a new style of brief, but effective, training in optical design. In 1982 Michael released for sale through Kidger Optics Ltd his optical design program SIGMA.

Teacher and Optical Designer
Michael Kidger developed a series of intensive, short courses, often using a 50-50 mix of theory and practical work. He concentrated on the application of aberration theory rather than its derivation. He showed, for example, how 3^rd order aberration theory could explain the performance expectation of a simple cemented doublet which students then verified by experience on a practical example. His teaching concentrated on theoretical and practical aspects of many different design types, all illustrated by practical examples. The aim was to teach a 'feel' for design and to show how classical aberration theory can be combined with modern software optimisers to achieve optimum solutions.

Michael was himself a talented and innovative lens designer. He produced designs that were simple and effective, and he was consummate in extracting the last ounce of performance from the minimum of surfaces. His work led to a deeper understanding of intrinsic limits to aberration correction under specific constraints and to novel interpretations of classical, but often poorly understood, aberration theory.

Michael John Kidger - In Memoriam
While on a teaching trip to Australia in February 1998, Michael passed away suddenly and unexpectedly. He is survived by his wife Tina, son David and daughter Julia. Tina, in conjunction with friends and associates of Michael's, has established the Michael J. Kidger Memorial Scholarship to assist students of optical design. She has also, with help from friends and former students of Michael's, arranged the posthumous publication of Michael's teachings in the two volume set "Fundamental Optical Design" and "Intermediate Optical Design" published by SPIE - The International Society for Optical Engineering.

Tina is, as always, Managing Director of the business she and Michael founded together in 1982 to further develop and market their optical design software under the trade name, SIGMA. The business continues today as Kidger Optics Associates, an optical design consultancy.

For an expanded and enlightening insight into Michael Kidger, please read Tina's Foreword to Fundamental Optical Design, Vol. I.