Each type of microscope operates on different principles:
- SEM: An electron beam is scanned across the sample surface, and the emitted secondary electrons are collected to form an image. - TEM: An electron beam is transmitted through an ultrathin sample, and the image is formed by the interaction of electrons with the sample. - AFM: A cantilever with a sharp tip scans the sample surface, and the deflection of the cantilever is measured to generate topographical images. - STM: A sharp conductive tip is brought very close to the sample surface, and the tunneling current between the tip and the sample is measured to produce an image.
