Microscopy
Microscopy comprises techniques for studying small structures by forming images from light, electron beams or interactions between a probe and a surface. Different methods reveal different aspects of a specimen: its shape, the position of particular molecules, or local physical properties. Light microscopy, electron microscopy and scanning probe microscopy use different mechanisms to obtain this information.[1][2]
Light microscopy
In bright-field microscopy, illumination passes through a specimen towards the objective lens. Transparent cells often produce little contrast. Phase-contrast microscopy and differential interference contrast make changes in the light's phase visible, revealing detail in otherwise difficult-to-see specimens. In fluorescence microscopy, fluorescent labels identify selected structures, such as particular proteins.[2]
Magnification describes the enlargement of an image; resolution concerns the detail it can distinguish. For conventional light microscopy, wavelength and the objective's numerical aperture determine the theoretical resolution. Increasing magnification alone does not establish that finer detail has been resolved.[2]
Confocal microscopy uses a pinhole to reject light originating outside the focal plane. Light-sheet microscopy instead restricts illumination to a thin plane. Super-resolution microscopy includes methods that resolve finer structures than conventional light microscopy, with additional demands on instrumentation or specimen preparation.[2]
Electron microscopy
In transmission electron microscopy, electrons pass through a very thin specimen to reveal internal structure. A scanning electron microscope moves a focused electron beam across a surface and records signals generated by its interaction with the specimen.[1]
Specimen preparation affects what becomes visible. Biological material can have weak inherent electron contrast; heavy-metal stains and thin sections help reveal cellular membranes. Another approach coats a surface with metal to make a replica for imaging. Such images show structure, but do not necessarily identify the molecules responsible for it.[3]
Scanning probe microscopy
A sharp probe moves across a surface while its local interaction with the specimen is measured. Scanning tunnelling microscopy measures a current produced by quantum tunnelling between the tip and an electrically conducting specimen. Atomic force microscopy measures forces acting on a probe attached to a cantilever; it can examine non-conducting specimens and operate in liquids. In addition to mapping surface shape, force measurements can investigate properties such as adhesion and stiffness.[1]
Combining methods
Correlative light and electron microscopy combines complementary observations of a specimen. Fluorescence can locate a labelled protein, while electron microscopy supplies surrounding structural detail that the fluorescent image does not show. Combining the two helps relate molecular identity to cellular organisation; neither image alone provides all this information.[3]
References
- ↑ 1.0 1.1 1.2 He, Songping; Yu, Xiaodong; Li, Weixing; Ji, Wei; Huan, Qing (2026-08-31). "Advances in scanning probe microscopy for biological systems". Biophysics Reports. 12 (4): 275–295. doi:10.52601/bpr.2025.250023. Retrieved 2026-10-14.
transmits a high-energy electron beam through an ultrathin sample ... AFM senses interatomic forces
- ↑ 2.0 2.1 2.2 2.3 Thorn, Kurt (2016-01-15). "A quick guide to light microscopy in cell biology". Molecular Biology of the Cell. 27 (2): 219–222. doi:10.1091/mbc.E15-02-0088. Retrieved 2026-10-14.
The objective determines the magnification and resolution of the image ... Light from out-of-focus planes is blocked by the pinhole
- ↑ 3.0 3.1 Taraska, Justin W. (2019-06-28). "A primer on resolving the nanoscale structure of the plasma membrane with light and electron microscopy". The Journal of General Physiology. 151 (8): 974–985. doi:10.1085/jgp.201812227. Retrieved 2026-10-14.
most biological objects have very little inherent contrast ... provide context and added structural or molecular information
Attribution
Attributed adaptation of English Wikipedia's Microscopy, revision 1376653227, consulted 14 October 2026. Contributor history. Prose substantially rewritten, scope condensed and references independently checked. Available under CC BY-SA 4.0.