Transmission electron microscopy (TEM) is a microscopy
technique in which a beam of electrons is transmitted through an
ultra-thin specimen, interacting with the specimen as it passes
through.
An image is formed from the interaction of the electrons
transmitted through the specimen; the image is magnified and
focused onto an imaging device, such as a fluorescent screen, on a
layer of photographic film, or to be detected by a sensor such as a
CCD camera. (A charge-coupled device is a device for the
movement of electrical charge)