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Dr Kenneth Smith

The College is very sad to report that Dr Kenneth Smith, Life Fellow of Fitzwilliam, passed away on Sunday 15 March.

Dr Smith, who was an undergraduate at Fitzwilliam House from 1949 and then a research student, subsequently became a Lecturer in the Department of Engineering, and joined Fitzwilliam as a Fellow in 1966 and was elected as a Life Fellow of the College in 1988. 

As a public mark of respect, we flew the College Flag at half-mast on Tuesday 17 March and again on the day of his funeral (Monday 30 March).

Dr. K.C.A.(Ken) Smith. Hon.FRMS

Born 20 March 1928; died 15 March 2020, aged 91

It is with great regret that we report the death of Dr Ken Smith just a few days before celebrating his 92nd birthday. Ken was a distinguished scientist and engineer and a key figure in the development of the SEM (Scanning Electron Microscope).

Kenneth Charles Arthur Smith was born in 1928 in Birmingham to Cyril and Marion Smith, owners of a radio and cycle shop, so Ken became very familiar with electrics and mechanics from an early age!  The Depression caused the family to relocate to Coventry, so Ken changed school to Meriden, from which he gained entry to Coventry Technical College, linked to an apprenticeship with BTH (British Thomson Houston Co.). He gained his ONC and HNC (Ordinary and Higher National Certificates) whilst helping the war effort by testing Rolls-Royce Merlin engine electrical components for Spitfires. Ending of the war in 1945 allowed Ken to pursue his further studies and he was offered places at Birmingham University and Fitzwilliam House in Cambridge. It is to our eternal benefit that he elected to take the latter, despite having to pass the then mandatory Latin entrance requirement which he did after a cramming course from his Latin master! He started in 1949, and after graduating in 1952 Charles Oatley offered him a position in his research group in Cambridge University Engineering Department (CUED).

Oatley had returned to Cambridge in 1947 after his wartime radar research work and with copious war surplus parts and novel devices was able to pursue his idea of making a scanning microscope despite earlier unsuccessful ventures in Germany and USA. His first student, Dennis McMullan had completed and successfully demonstrated SEM1 thus producing the first real scanning microscope embodying many principles with which we now are so familiar. Ken took over this instrument from Dennis and spent long hours learning to operate it (its electrostatic lenses were notoriously unstable in the poor vacuum conditions!) before using his talents to implement a whole range of improvements and understand the fundamental role that secondary electrons played in the imaging and contrast generating processes by examining a wide range of samples. As part of his duties he even showed Marshal Tito and Prince Philip the SEM during these early days. SEM imaging had yet to be appreciated by microscopists; the proven replica method in the TEM was the convention for looking at the surfaces of solid samples. Through Ken’s assiduous work it was becoming evident that with further improvements the SEM could offer a real challenge. To make this work relevant he needed to compare results from the SEM and the replica method - his source and mentor in these investigations became Sheila Vernon Smith who was an acknowledged expert in replica applications in metallurgy using the TEM. Sheila was working at the time as the electron microscopist at the Agricultural Research Council’s Virus Research Unit in Cambridge. This serendipitous association developed over time culminating in their marriage in 1957 (despite any number of hair-raising exploits on Ken’s Triumph Twin 350cc motorcycle!)

It is relevant to note the close association of Oatley’s group with Ellis Cosslett’s group working in the Cavendish Laboratory on x-ray generation and electron beam interactions in materials – this group included key future players in the field – Peter Duncumb, Bill Nixon, Jim Long and many others who contributed to the development and commercialisation of the Microscan X Ray Microanalyser by the Cambridge Instrument Co. in the early 1960’s. This close relationship between the two departments continued for many years, involving Ken in other later projects.

Ken’s post-doctoral work continued in further developing the SEM - he was encouraged in this by Doug Atack from the Pulp and Paper Research Institute of Canada (PPRIC) whose wood and pulp sample results provoked so much interest that the Institute were prepared to support the construction of a new SEM to Ken’s demanding specification and to offer him a post in Montreal. This new instrument (SEM3) was constructed in CUED and shipped to Canada.

At this time, AEI, the only UK manufacturer of EMs had been encouraged by Oatley to consider the commercial possibility for the SEM. They supported the project with hardware and design knowledge on magnetic lenses (Ken had seen that these offered a far more satisfactory and stable electron optical column). Furthermore, the pinhole objective lens design from Liebmann’s analysis at AEI was a fundamental step in improving SEM resolution and allowing the sample to be in a low field region, critical for the detection of low energy secondary electrons for image formation in the SEM.

He also took advantage of the research work in Oatley’s group of Tom Everhart and Richard Thornley in the design of the scintillator/photomultiplier detector now found in most SEMs, but which was a ground breaking improvement over the hitherto used open electron multiplier detector. As an aside, Ken also built the first water vapour cell for biological sample examination in the SEM – a precursor to today’s environmental SEMs. This used a scintillator both as detector and seal to the cell, thereby showing that a scintillator would be a good detector for the SEM and setting the Thornley - Everhart work on track. He never published this work.

Ken determined that a column with 3 lenses would allow comprehensive control of the probe parameters of diameter and current and he is acknowledged as the author of the fundamental performance equation for the SEM still used today. He also employed the magnetic double deflection system used by McMullan with its crossover in the principal plane of the final lens. This allowed the probe to be deflected through larger angles and hence achieve lower magnifications without incurring gross aberrations. The column included magnetic stigmators for the compensation of lens aberrations and beam limiting apertures in critical locations on the column axis. He had already been unwittingly misled in SEM1 by not appreciating that scattered electrons in columns would seriously degrade final performance and imaging resolution – he wasn’t going to repeat that error again!

Thus, in this single instrument design Ken had incorporated features that we now take for granted in our modern SEMs.

During the construction of this microscope Ken and Sheila tied the knot on 28 September 1957 with their wedding in the old Norman church of St Mary’s in Hemel Hempstead – the congregation included many from the Oatley research group. They honeymooned in Torridon, a favourite area of Scotland, using Ken’s new second love a red 1933 Alvis Speed 20 Roadster, the rather safer four wheel replacement for his trusty Triumph. The car cost a princely sum of £135 (n.b. To buy it in 2020, close to £100k! = a modern SEM) but he sold the motorbike for £25 to another research student!

It was inevitable that building SEM3 took considerable time and resources in the Dept. which caused certain practical difficulties, but eventually, early in 1958 Ken felt sufficient progress in instrumentation and  imaging had been achieved to allow it to be shipped to Montreal via AEI in Manchester - however a small dilemma ensued when the doorway proved too narrow for the instrument to leave – a large saw wielded by a lab assistant dealt with this and it was on its way. Ken and Sheila left in April and despite a rough sea crossing arrived safely in Montreal to begin their joint two-year contract to install and train the users at the PPRIC. Thus, the very first commercial SEM was installed and served for many years before it was retired - a tribute to its excellent design and first-class engineering.

As a footnote to this work AEI failed to capitalise on the venture and it was a further period of 3/4 years before Nixon, Smith and Oatley encouraged Cambridge Instruments to look at the design with a view to developing it as an evolution of their successful Microscan. In the event Gary Stewart moved from CUED with Oatley’s blessing but insisted that a brand-new microscope design was developed to facilitate future production - this became the world famous Stereoscan launched in 1965 but that is another story!

Ken’s career now took a new path and he was offered a position by Ellis Cosslett in the Cavendish which he took up in spring 1960 when he, Sheila and their new son Laurence flew back to the UK – a much more pleasant experience than the outbound journey. Cosslett was surprised to see him as he had expected him in October, but a good meal and a bottle of wine soon cleared the air!  Ken and Sheila now found time to look for a house, which they found in the village of Abington. Despite the challenging commitment an old cottage provided, this became their idyllic home for many years.

Ken initially continued work in the Cavendish on an x -ray microscope which Bill Nixon had been developing. Soon Cosslett was successful in securing a grant from the Paul Instrument Fund to build a High Voltage Electron Microscope - Ken applied and was appointed to lead the project. This was to design and build a 750kV TEM to evaluate beam interactions in thick samples and to assess microscopy benefits of these higher voltages compared with the conventional TEMs of that time. The instrument was designed to provide a wide operational voltage range from 50 to 750 kV to facilitate these comparisons. This project ran for several years, Ken‘s involvement covered a very wide range of aspects which fully exercised and demonstrated his superb ability as a project leader, engineer, scientist and coordinator. These included the significant structural works in a listed building to accommodate the electron gun and accelerator structure for the column and Swiss supplier Haefely’s large air insulated EHT set (using a Cockcroft-Walton multiplier which was highly appropriate, as the TEM was housed in the very building in which these HV devices were used in the 1930’s for nuclear research). The choice of a suitable high stability HV supplier from the few available had taken a considerable effort in the early days of the project, and many visits to the Continent ensued (with the inevitable gastronomic pleasures) before the Haefely design was accepted.  Extensive safety x-ray shielding, column optics design and manufacture and safe remote operation of the TEM were also major projects in their own right. Fire safety precautions were always to the forefront of the facility with the operator’s emergency exit being a trap door from the basement room into Free School Lane next to a drain cover! The first successful images came in 1966 just before Ken relocated to CUED, but he retained his interest in the project for many months thereafter. AEI, who had been involved in the project, took on the design and developed the EM7 TEM using a 1 MeV Haefely unit and successfully selling 12 of these HVEMs to users across the world.

Ken and Ellis Cosslett were jointly awarded the Institute of Physics Duddell Medal and Prize (later called the Gabor Medal) in 1971 for their outstanding pioneering practical work on the HVEM. Ken and Sheila always considered that this period of their lives was their happiest for family and work.

From 1966 to his retirement in 1988 Ken was a lecturer and then Reader in Electrical Engineering in CUED and continued in new fields of research into the use of field emission cathodes for microscopy and the ways in which computers could be used to control microscopes. These features are so integrated into modern microscopy that we now take them for granted but without this earlier work based on extensive and practical experience of an acknowledged expert perhaps it might have been a far longer path.

It was during this period that a further joint project between the Cavendish and the Engineering Dept. came to fruition and this was the Cambridge University High Resolution Microscope (HREM) with the target to achieve atomic resolution and operating up to 600kV. This was funded from 1972 with Nixon and Cosslett as principal investigators and was the follow up to the earlier Cavendish work. Ken with his breadth of experience played a key role in achieving a successful outcome for this project with his former research students John Catto and John Cleaver being significant contributors.

Due to ill health, he retired from the Engineering Department in 1988, but continued to publish for some years, co-authoring (with Ruben Alley) an important book on the subject of electrical circuitry: 'Electrical Circuits: an introduction' – a comprehensive text for students first published in 1992, and editing, with Bernie Breton and Dennis McMullan, a volume on the history of the SEM work by Oatley’s group, published in ‘Advances in Imaging and Electron Physics’, 133 (2004). His personal memoirs of his work on the SEM and HVEM were published in the same series in 2013.

Together with colleagues, Ken also initiated two ‘start-up’ companies to commercialise results of their research: Granta Electronics, marketing software to aid in the design of electron lenses and Synoptics (now part of the SDI Group PLC) for applications of digital image processing He was Chairman of the latter company until his retirement.

His lifelong contributions to the science of electron microscopy are well known and recognised. In 1971 he, with Cosslett, had been jointly awarded the Duddell Medal and Prize for the work on the HVEM; elected Honorary Fellow of the Royal Microscopical Society in 1984 and then chosen as Distinguished Scientist( Physics) by the Microscopy Society of America (MSA) in 1993; he was a Fellow of the Institute of Electrical Engineers and a Life Fellow of Fitzwilliam College, Cambridge.

Ken had a lifelong interest in music, initially stimulated by jazz in the 1940’s, but Bach and organ music became his passion and latterly, the music of the French composer Charles-Valentin Alkan, leading to establishing the Alkan Piano Scholarship at Fitzwilliam College. He also had a common interest with Sheila in hill walking and other outdoor activities, until ill health precluded these.

Ken’s passing has left the microscopy community a far poorer place – he was a humble and retiring participant but without his enthusiasm, commitment and hard earned analytical, engineering and scientific skills we would perhaps not have achieved the ability to look at our world today so quickly and competently – he is sadly missed by family, friends , colleagues and the wider community - may he rest in peace.

On behalf of the Royal Microscopical Society and myself we extend our condolences to Sheila and Laurence.

Dr. Richard Paden, Hon. FRMS

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