Physical Principles of Electron Microscopy: An Introduction to TEM ...

An Introduction to Microscopy 13
Figure 1-9. First commercial TEM from the Siemens Company, employing three magnetic
lenses that were water-cooled and energized by batteries. The objective lens used a focal
length down to 2.8 mm at 80 kV, giving an estimated resolution of 10 nm.
Although companies in the USA, Holland, UK, Germany, Japan, China,
USSR, and Czechoslovakia have at one time manufactured transmission
electron microscopes, competition has reduced their number to four: the
Japanese Electron Optics Laboratory (JEOL) and Hitachi in Japan,
Philips/FEI in Holland/USA, and Zeiss in Germany.
The further development of the TEM is illustrated by the two JEOL
instruments shown in Fig. 1-10. Their model 100B (introduced around 1970)
used both vacuum tubes and transistors for control of the lens currents and
the high voltage (up to 100 kV) and gave a spatial resolution of 0.3 nm.
Model 2010 (introduced 1990) employed integrated circuits and digital
control; at 200 kV accelerating voltage, it provided a resolution of 0.2 nm.