 Atomic force microscopy

Atomic force microscopy maps surfaces and measures small interactions using a sharp tip attached to a compliant cantilever. In a common modern readout, a laser reflects from the cantilever onto a split photodetector, turning bending into an electrical signal. A scanner moves the tip relative to the sample; feedback can adjust height to maintain a chosen interaction signal. With calibrated stiffness $k$, a small static deflection $\delta$ gives force $F\approx k\delta$. The measured image combines surface geometry, tip geometry and interaction physics, so narrow features can appear broadened. Gerd Binnig, Calvin Quate and Christoph Gerber introduced the instrument in 1986.^[ref] Modern force measurements additionally require calibrated cantilever stiffness.^[ref]