According to [Asianometry], no one believed in the scanning electron microscope. No one, that is, except [Charles Oatley].The video below tells the whole story.
The Cambridge graduate built radios during World War II and then joined Cambridge as a lecturer once the conflict was over. [Hans Busch] demonstrated using magnets to move electron beams, which suggested the possibility of creating a lens, and it was an obvious thought to make a microscope that uses electrons.
After all, electrons can have smaller wavelength than light, so a microscope using electrons could — in theory — image at a higher resolution. [Max Knoll] and [Ernst Ruska], in fact, developed the transmission electron microscope or TEM.
The TEM works by passing an electron beam through a very thin sample and detecting it on the other side. However, the goal was to build an electron device that bounced electrons off an object — a SEM or scanning electron microscope. [Knoll] did build a device using this principle. However, it had a broad beam and could only magnify 10X or so, and it did not scan like a modern scope.
A practical SEM would wait for [Manfred Baron von Ardenne] in 1937. Working with Siemens (who, yes, owns Hackaday), he created a crude SEM. It took 20 minutes to create an image on a piece of film, so it wasn’t very practical. After two years, World War II broke out, and the work was lost.
At RCA, [Vladimir Zworykin] did some work on SEM, but abandoned the poorly-working device as TEM devices were more attractive. Then, in the 1950s, [Charles Oatley] decided he wanted to build an electron microscope for Cambridge.
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