Scanning electron microscope. Sample stage (centre) of a combined scanning electron microscope (SEM), scanning auger microscope (SAM) and scanning probe microscope (SPM). The SEM scans a sample with a beam of electrons. The beam may be scattered off the sample or it may cause electrons to be emitted by it. These electrons are collected and translated into a three-dimensional image. The SAM can find the chemical composition of a sample on a microscopic scale. The SPM can image or alter material structures through the interaction of its probe with the material's surface. Photographed at the Centre for Nanoscale Science and Technology at the University of Newcastle upon Tyne, England.