The scanning electron microscope (SEM) has been des-cribed as the single most important scientific instrument of the post-war era. Charles Oatley pioneered its dev- elopment at the Cambridge University Engineering Depart-ment in the decades immediately following the Second World War.
Manufacture of the first commercial production model commenced in 1965; thousands have since been made and are to be found in practically every research laboratory in the world. The striking three- dimensional images of microscopic organisms the instrument produces have been used to illustrate countless newspaper and magazine articles, as well as scientific research papers, which have given the general public a new perspective and appreciation of the world that lies beyond the resolution of the human eye.
Oatley was born in Frome, Somerset. His father, William, was the owner of a flourishing bakery business, and his mother, Ada Mary Dorrington, a school teacher. Although lacking any formal scientific education William Oatley was intensely interested in scientific matters and passed this enthusiasm on to his son. He gave Charles an electric motor on his sixth birthday - not a common toy in 1910 - and he possessed a Watson Royal microscope which he taught his son to use.
Charles Oatley's first taste of education was at a small dame school, close to his home. In a delightful family memoir he recounts how at the age of five, accompanied by an older pupil, he set forth, armed with a slate, some slate pencils and a small sponge (to clean the slate) in an empty Lyle's Golden Syrup tin - a modest beginning to an academic career that would lead to the Royal Medal of the Royal Society.
This was followed by 10 years at a local council school, and then to Bedford Modern School as a boarder from where he won exhibitions to St John's College, Cambridge.
At Cambridge he read for the Natural Sciences Tripos, taking a First in Part I and a Second in Part II (Physics). He also obtained a half-blue for swimming, and captained the University Swimming team in his final year. His supervisor at St John's was E.V. Appleton (of Appleton layer fame - a layer in the ionosphere which reflects radio waves); it was he who first aroused Oatley's interest in electronics, and was to have a profound influence on his subsequent career.
On Appleton's advice Oatley obtained in 1925 a job with Radio Accessories in Willesden, a small company manufacturing radio valves; here he gained valuable experience of manufacturing techniques and, as the only graduate in the company, was called upon to tackle a wide variety of practical physics problems. After two years, however, he was invited to return to academic life by Appleton, who had meanwhile moved to the Physics Department at King's College London.
The next 12 years at King's were spent largely teaching and examining, with little time for research, but they were, as Oatley acknowledges in his writings, among the happiest of his life. It was in this period that he married Enid West. He also published a useful little book, Wireless Receivers (1932), that was read widely by enthusiasts.
At the onset of war in 1939, he was asked by J.D. Cockcroft, whom he had met at St John's, to join a team at the Air Defence Experimental Establishment (ADEE) at Christchurch, Dorset, which was being formed to work on the development of what was to become known as radar. Oatley was given the task of building up a Measurements Group to carry out measurements on components under construction in the Establishment - aerials, transmitters, receivers, modulators, displays and so forth. In the last year of the war he was appointed acting-superintendent of the establishment, which numbered some 1,000 people, and which by this time was located at Malvern under the name of the Radar Research and Development Establishment. His contribution to the achievement of the British superiority in wartime developments in radar was very considerable.
After the war he was offered a Fellowship at Trinity College, Cambridge, and a Lectureship in the Engineering Department, which was then under the dynamic leadership of Sir John Baker. With Baker's encouragement, Oatley revolutionised the teaching of electrical subjects in the De-partment, particularly electronics, with the introduction of the Electrical Sciences Tripos. This produced a stream of able research students and additional teaching staff, which in the following decades played a significant part in the development of the scanning electron microscope. He was elected to the Chair of Electrical Engineering in 1960.
Charles Oatley's interest in the SEM was first aroused when he learned of pre-war work by M. von Ardenne in Germany and V.K. Zworykin in the United States. This had produced inconclusive results, but with his wartime experience Oatley realised that new techniques and methods were available which could be applied to the scanning concept. More importantly, to his way of thinking, research on the scanning electron microscope principle offered the ideal avenue through which to apply his extensive experience, and to stretch his own mind and those of his future research students.
His first research student, D. McMullen, began in 1948, and a working instrument was produced by 1951. This incorporated a novel configuration of the electron optical image-forming elements, producing startlingly realistic images of surfaces, capable of interpretation even by the uninitiated.
Oatley was convinced that the SEM would turn out to be an important laboratory tool; however, this was far from being the consensus among microscopists who, by and large, believed that this new instrument could never compete with the well- established electron microscopical techniques of the time. It was met with indifference and even, in some quarters, ridicule.
Nothing daunted, Oatley took on more research students and ploughed more effort and money into the project: L. Peters, a gifted technician, was assigned to it, new instruments with improved performance were constructed, and new fields of application explored. Among the many notable developments in the two decades following was the extension of the technique to electron beam microfabrication, which has had a major impact in the manufacture of microcircuit chips for computers.
After many false starts and disappointments, Oatley's faith and tenacity were finally rewarded in 1965 with the launch of the world's first series production SEM: the Stereoscan, manufactured by the Cambridge Instrument Company. His book on the subject, The Scanning Electron Microscope, was published in 1972.
Many honours followed from this success: election to the Royal Society and receipt of its Royal Medal and Mullard Award; Fellowship of the Royal Academy of Engineering; Fellow of King's College London; a knighthood in 1974.
Charles Oatley was held in great esteem by his colleagues, and was regarded with affection by all who worked closely with him, particularly his research students with many of whom he and his wife established lifelong friendships. This was manifest on the occasion of his 90th birthday when a one-day seminar was held in his honour at Churchill College. Over 100 attended - colleagues, research students, and workers in scanning electron microscopy and related fields from across the globe.
and K.C.A. Smith
Charles William Oatley, engineer: born Frome, Somerset 14 February 1904; Demonstrator, later Lecturer, King's College London 1927-39; Lecturer, later Reader, Department of Engineering, Cambridge University 1945-60, Professor of Electrical Engineering 1960-71 (Emeritus); OBE 1956; FRS 1969; Kt 1974; married 1930 Enid West (two sons); died Cambridge 11 March 1996.
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