microscope

A microscope is an instrument designed to magnify small objects and reveal details that are not visible to the naked eye. By combining lenses or other imaging technologies, a microscope increases both apparent size and the ability to distinguish fine structures. Common metrics include magnification and resolution, the latter describing the smallest detail that can be discerned. In optical systems, light or other radiation is focused through objectives and eyepieces, with illumination and a stage to hold the specimen.

There are several major families of microscopes. Light (optical) microscopes use visible light and glass lenses. Compound microscopes typically employ multiple lenses to achieve high magnification, while stereo or dissecting microscopes provide lower magnification with a three-dimensional view for larger, living specimens. Fluorescence, phase-contrast, and differential interference contrast techniques enhance contrast for transparent or unstained samples.

Electron microscopes use beams of electrons rather than light, achieving far higher resolution. Transmission electron microscopes (TEM) reveal internal structures at the nanometer scale, whereas scanning electron microscopes (SEM) produce detailed three-dimensional surface images. Both require vacuum systems and special sample preparation.

Scanning probe microscopes map surfaces at the atomic level without optical lenses. The atomic force microscope (AFM) and scanning tunneling microscope (STM) are prominent examples, capable of imaging individual atoms on material surfaces.

Historical developments trace the first practical devices to the late 16th century, with significant improvements by figures such as Antonie van Leeuwenhoek and Robert Hooke. Today, microscopes are essential across biology, medicine, materials science, and beyond, supported by digital imaging, automation, and diverse contrast techniques.