The SuperSTEM project began in 1997 when Prof. Mick Brown presented a paper at the EMAG conference in Cambridge entitled "A Synchrotron in a Microscope".
He challenged the UK microscopy community to pool resources to exploit the emerging technology of spherical aberration correction. One of the first people to show that spherical aberration could be overcome was Prof. Ondrej Krivanek who had returned to Cambridge to work with Prof. Brown in the Microstructural Physics group. The project was funded by the Engineering and Physical Sciences Research Council (EPSRC) in 2001 and by that stage consisted of lead scientists from the Universities of Leeds, Cambridge and Liverpool with Prof. Peter Goodhew as the principal investigator. The final makeup was largely serendipitous because the project has had strong support from a large number of people and organisations but, with the addition of Glasgow University, has proved a very effective team.
The first instrument (SuperSTEM1) made use of the Cambridge VG HB 501 dedicated STEM. Aberration correction is achieved by retrofitting a Nion Mark II quadrupole-octupole corrector. As a result the spatial resolution was doubled from ~2 Å to 1 Å. Many new and important results have been obtained from this microscope but from the beginning it was clear that the 30 year old design of the VG microscopes were not optimised for aberration correction. Nion's response was to build an entirely new microscope (i.e. the UltraSTEM™ 100) that overcame these difficulties and SuperSTEM2 is the first such instrument in use for scientific research. Apart from optimised performance the UltraSTEM™ 100 has several features found in no other microscope such as 5th order aberration correction, a 2 Å electron probe mode with >0.5 nA current for rapid atomic-scale EELS mapping as well as a nano-diffraction mode.
In a perfect lens all rays that emerge from a point object P are brought to focus at a conjugate point P´ in the image plane. The image is therefore a true representation of the object being imaged. In reality high-angle rays (the solid lines in the figure) are brought to a premature focus by lens aberrations so that the point object P appears blurred in the image plane. This phenomenon is called spherical aberration. The most famous recent example of the catastrophic effects of spherical aberration is the Hubble space telescope; here distant stars, which should have appeared as bright dots in the image, were found to have their intensities smeared out due to a very small error in the curvature of the mirror at its edges.