<P> The different types of scanning probe microscopes arise from the many different types of interactions that occur when a small probe of some type is scanned over and interacts with a specimen . These interactions or modes can be recorded or mapped as function of location on the surface to form a characterization map . The three most common types of scanning probe microscopes are atomic force microscopes (AFM), near - field scanning optical microscopes (MSOM or SNOM, scanning near - field optical microscopy), and scanning tunneling microscopes (STM). An atomic force microscope has a fine probe, usually of silicon or silicon nitride, attached to a cantilever; the probe is scanned over the surface of the sample, and the forces that cause an interaction between the probe and the surface of the sample are measured and mapped . A near - field scanning optical microscope is similar to an AFM but its probe consists of a light source in an optical fiber covered with a tip that has usually an aperture for the light to pass through . The microscope can capture either transmitted or reflected light to measure very localized optical properties of the surface, commonly of a biological specimen . Scanning tunneling microscopes have a metal tip with a single apical atom; the tip is attached to a tube through which a current flows . The tip is scanned over the surface of a conductive sample until a tunneling current flows; the current is kept constant by computer movement of the tip and an image is formed by the recorded movements of the tip . </P> <P> Scanning acoustic microscopes use sound waves to measure variations in acoustic impedance . Similar to Sonar in principle, they are used for such jobs as detecting defects in the subsurfaces of materials including those found in integrated circuits . On February 4, 2013, Australian engineers built a "quantum microscope" which provides unparalleled precision . </P>

Who used a compound microscope to see the first cells