The first vision aid invented (inventor unknown) was the reading stone. It was a glass sphere that magnified when laid on top of reading materials. It is considered an early precursor to the microscope.
What is a Electron Microscope?
In this kind of microscope, electrons are speeded up in a vacuum until their wavelength is extremely short, only one hundred-thousandth that of white light. Beams of these fast-moving electrons are focused on a cell sample and are absorbed or scattered by the cell's parts so as to form an image on an electron-sensitive photographic plate. If pushed to the limit, electron microscopes can make it possible to view objects as small as the diameter of an atom. Illustration: LOC