Metropolitan Vickers EM2 electron microscope, 1946.
© Science Museum / Science & Society Picture Library
This was the first electron microscope to be produced in quantity in the British Isles. Each of the two lenses has a maximum magnification of 100, giving an overall magnification of 10,000. This could be increased to 50,000 by enlarging the plates photographically. The accelerating voltage of 25-50 KV was regarded at that time as the most suitable and economical for a general purpose instrument.