All of them need a vacuum because you can't shoot elecrons through air, as mentioned at Video "50,000,000x Magnification by AlphaPhoenix (2022)".
An electron microscope is a type of microscope that uses a beam of electrons to illuminate a specimen and create an image. Unlike light microscopes, which use visible light and lenses to magnify objects, electron microscopes can achieve much higher resolutions, allowing scientists to observe fine details at the nanometer scale, far beyond the capabilities of traditional optical microscopes.
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