VIII. CAMBRIDGE UNIVERSITY HIGH RESOLUTION ELECTRON MICROSCOPE
Contributed by K. C. A. Smith
The Cambridge HREM was a collaborative venture between the Department of Engineering and the Cavendish Laboratory, the purpose of which was to construct and commission a very high resolution transmission electron microscope. It was financed by the Engineering Board of the Science Research Council, with contributions from Cambridge University and the Royal Society. Although not directly related to the subject of Volume 133, the involvement in this project of members of the CUED stemmed directly from the expertise in electron optical systems and electronics built up over the years as a result of Charles Oatley's original decision to take up research on the SEM. Design of the HREM commenced in 1972.
Bill Nixon was the principal investigator for the CUED, assisted by Haroon Ahmed and Ken Smith. John Cleaver was responsible for column and lens design, while John Catto designed most of the high stability electronic systems, and was responsible for the low-light-level TV camera. The anti-vibration suspension system was designed by Philip Turner and Arthur Timbs. Bernie Breton who joined the group in 1981, designed and installed computer control of magnification and diffraction, which greatly simplified operation of the instrument.
For the Cavendish Laboratory Ellis Cosslett was principal investigator. David Smith, assisted by Roger Camps, Len Freeman and Ron Pryor, was responsible for commissioning the instrument and its day-to-day operation, and Owen Saxton was concerned with image interpretation and computational image processing. Peter Hawkes acted in an advisory capacity in the planning stages of the project. A brief description of the engineering aspects of the instrument was published in 1977 (Nixon et al., ref. 1) and some preliminary results demonstrating atomic resolution appeared in Nature in 1979. (Cosslett and Nixon et al., ref. 2). Further details and applications of the microscope were published over subsequent years; Refs. 3–9 is a representative list up to 1984. Additionally, there were at least 8 Nature articles (and 5 front cover illustrations) detailing results obtained with the Cambridge HREM.
A photograph of the microscope is shown in [DJ Smith, Column]. The lens stack is based on the AEI EM7 high voltage microscope (Agar et al., 1970, Ref. 10). The accelerator stack (Haefely) is shown in [DJ Smith, Accelerator]. A micrograph demonstrating atomic resolution is shown in [DJ Smith, Micrograph] (for details see ref. 9). The HREM was decommissioned in the early 1990s.
Several students from the Engineering Department gained their PhDs working on various aspect of the HREM. These students, who were supervised at different times jointly by Ken Smith, Owen Saxton and David Holburn, included Michael Chang (1988), Ka Lok Chau (1993) and Gopal Chand (1994), as well as Steve Erasmus, Ray Hill and Phil Atkin, whose work is described in Section IV. Although not directly related to the mainstream research on the SEM, their work represented a considerable contribution to the general electron optical effort within the Engineering Department, consequently their dissertations are listed below and included in the bibliography on this website.
REFERENCES
(1) Nixon, W. C., Ahmed, H., Catto, C. J. D., Cleaver, J. R. A., Smith, K. C. A., Timbs, A. E., Turner, P. W. & Ross, P. M. Some aspects of the engineering design and construction of the Cambridge University 600 kV high resolution electron microscope. (1977) Developments in Electron Microscopy and Analysis (Ed. by D. L. Misell), 13-16. Institute of Physics, Bristol and London.
(2) Cosslett, V. E., Camps, R. A., Saxton, W. O., Smith, D. J., & Nixon, W. C., Ahmed, H., Catto, C. J. D., Cleaver, J. R. A., Smith, K. C. A., Timbs, A. E., Turner, P. W., Ross, P. M. Atomic resolution with a 600-kV electron microscope. (1979) Nature, 281, 49-51.
(3) Cosslett, V.E. Principles and performance of a 600 kV high resolution electron microscope. (1980) Proc. Roy. Soc. Lond. A, 370, 1.
(4) Smith, D. J., Camps, R. A., Cosslett, V. E., Freeman, L. A. Saxton, W. O. & Nixon, W. C., Ahmed, H., Catto, C. J. D., Cleaver, J. R. A., Smith, K. C. A., Timbs, A. E. (1982) Optimisation and applications of the Cambridge University 600 kV high resolution electron microscope. Ultramicroscopy, 9, 203–214.
(5) Catto, C. J. D., Smith, K. C. A., Nixon, W. C., Erasmus, S. J., Smith, D. J. An image pickup and display system for the Cambridge University HREM. Electron Microscopy and Analysis (1981) (Ed. by M. J. Goringe), 123–126. Institute of Physics, Bristol and London.
(6) Cleaver, J.R.A. Some optical characteristics of the saturated symmetrical condenser-objective lens. (1978) Optik, 49, 413.
(7) Smith, D. J., Camps, R. A., Freeman, L. A., Hill, R., Nixon, W. C., Smith, K. C. A. (1983). Recent improvements to the Cambridge University 600 kV High Resolution Electron Microscope. J. Microscopy, 130, Pt 2, 127-136.
(8) Saxton, W. O., Smith, D. J., and Erasmus, S. J. Procedures for focusing, stigmating and alignment in high-resolution electron microscopy. (1983) J. Microscopy, 130, 187–201.
(9) Bursill, L. A. & Smith, D. J., (1984) Interactions of small and extended defects in nonstoichiometric oxides. Nature, 309, 319–321.
(10) Agar, A. W. et al., (1970) A new 1000kV electron microscope. Proc. Int. Cong. Electron Microscopy, Grenoble, 1970, 115–116.
ENGINEERING DEPT. STUDENT REFERENCES
Atkin, P. (1989). A programmable image processor. Ph.D. Dissertation, University of Cambridge.
Chand, G. (1994). Aberration determination and compensation in high resolution transmission electron microscopy. Ph.D. Dissertation, University of Cambridge.
Chang, M. M. Y (1988). A computer-controlled system in transmission electron microscopy. Ph.D. Dissertation, University of Cambridge.
Chau, K. L. (1993). Automated control in high resolution electron microscopy. Ph.D. Dissertation, University of Cambridge.
Erasmus, S. J. (1982). Real-time digital image processing in electron microscopy, Ph.D. Dissertation. University of Cambridge
Hill, R. (1982). Investigations relating to the single-pole magnetic lens, Ph.D. Dissertation. University of Cambridge.