An instrument used to see objects too small for the naked eye, requiring stability.A microscope is an instrument that magnifies objects too small to be seen with the naked eye, such as cells, bacteria, or individual atoms. The core challenge in microscopy is stability: any vibration or drift blurs the image, so high-resolution microscopes are built on heavy, isolated tables and use feedback systems to correct for thermal expansion or mechanical noise. Modern microscopes extend far beyond simple magnifying glasses, using electrons, X-rays, or even quantum effects to probe matter at scales from micrometers down to picometers.
The first compound microscopes were built in the late 16th century by Dutch spectacle makers, with Antonie van Leeuwenhoek later using simple single-lens designs to observe bacteria and sperm cells in the 1670s. The electron microscope was invented in 1931 by Ernst Ruska and Max Knoll, and the scanning tunneling microscope followed in 1981, developed by Gerd Binnig and Heinrich Rohrer at IBM Zurich.
Most microscopes work by focusing some form of radiation—visible light, electrons, or X-rays—onto the sample and then magnifying the resulting signal with lenses or detectors. The resolution is limited by the wavelength of the radiation used: visible light can distinguish features about 200 nanometers apart, while electron microscopes, using much shorter wavelengths, can resolve individual atoms. For scanning probe microscopes, a sharp tip physically scans the surface, measuring forces or electric currents point by point to build an image without any lenses at all.
Microscopes are essential in biology, medicine, materials science, and nanotechnology—from diagnosing diseases in tissue samples to inspecting semiconductor chips and developing new materials at the atomic scale.
The scanning tunneling microscope is so sensitive that it can image individual atoms, and its tip is typically sharpened down to a single atom at its very end.
