A microscope is an optical or electronic instrument used to magnify and resolve details of objects too small to be seen clearly with the unaided eye.
Explanation
The basic function of a microscope is to magnify and improve resolution of specimens so that cellular or subcellular structures become visible. Light microscopes use lenses and visible light to produce an enlarged image; the compound light microscope, developed from early designs by Hooke and Leeuwenhoek, employs multiple lenses (objective and ocular) and illumination through a condenser. Resolution is limited by the wavelength of light (~200 nm), but techniques such as phase contrast, differential interference contrast and fluorescence microscopy enhance contrast and reveal specific structures. Electron microscopes substitute electron beams for light, achieving much higher resolution. Transmission electron microscopes (TEM) pass electrons through ultra‑thin specimens to visualize internal structures at the nanometre scale, while scanning electron microscopes (SEM) scan a focused beam across a specimen to generate a three‑dimensional surface image. Proper sample preparation—including fixation, staining and sectioning—is critical for optimal imaging. Microscopes have become indispensable in biology, medicine and materials science, allowing researchers to observe cells, organelles, microorganisms and nanomaterials.
Types and Uses
Light microscopes are common in teaching and clinical laboratories for examining tissues, bacteria and protozoa. Phase contrast and differential interference contrast microscopes enhance visualization of unstained live cells. Fluorescence microscopes use fluorophores and specific wavelengths to detect proteins, nucleic acids or pathogens. Confocal laser scanning microscopes collect optical sections to reconstruct three‑dimensional images of thick specimens. Transmission electron microscopes reveal viruses, ribosomes and membranes at near atomic resolution, whereas scanning electron microscopes are used for detailed surface morphology of cells, insects or materials. Understanding the capabilities and limitations of each type guides appropriate choice for a given application.
Microscopes enable discoveries across many disciplines, from diagnosing infections to developing nanotechnology. Mastery of microscopy is fundamental to understanding the microcosm.
Related Terms: Microscopy, Objective lens, Magnification, Resolution, Light microscopy