ABSTRACT
In Chapter 2 most of the essential parts of a TEM were described. The illumination is provided by an electron gun while the lenses are all electro magnetic and work as described in section 2.4. The remaining necessary com ponents are a viewing screen - usually a simple layer of electron-fluorescent material, viewed through a lead glass window - and a camera, which must work in the vacuum within the microscope. These components are assembled into a vertical ‘microscope column’ of which a typical example is shown in Figure 4.1. Most of the thickness of the column is taken up with the windings of the lens coils, the pole pieces, and pipes of cooling water - the electrons
travel down a fine tube in the centre which rarely exceeds a millimetre or so in diameter.
