What’s an electron microscope?
If you looked down the most powerful light microscope in the world, you’d be able to distinguish individual objects that are around 200 nanometres apart – roughly 1/500 the width of a human hair. But objects closer together than that would just merge into one. This is because the wavelength of visible light is longer than 200 nanometres. But electron microscopes use beams of electrons, instead of light. The wavelength of these electron beams is much shorter, allowing scientists to see structures as small as 1 nanometre (1 millionth of a millimetre). There are two types of electron microscopes, creating different types of images for different purposes. Transmission electron microscopes (TEM) fire beams of electrons straight through prepared samples of cells, picking up fine details of the tiny structures within. This technique allows scientists to see what’s going on deep within a cell – effectively a “molecule’s eye view”. Scanning electron microscopy (SEM) is slightly different. Inste
