Lab & analytical techniques · Reference
What is microscopy?
Microscopy is the use of lenses or beams of radiation to magnify objects too small for the eye, resolving fine detail in cells, materials, and structures by gathering and focusing light or electrons.
The physics of magnification and resolution
A microscope produces a magnified image by focusing radiation that has interacted with the specimen. Two properties matter: magnification, how much larger the image appears, and resolution, the smallest separation at which two points can still be told apart. Resolution is fundamentally limited by the wavelength of the radiation — the diffraction limit — so visible light cannot resolve features much below about 200 nanometres. Using radiation of shorter wavelength, such as a beam of electrons, pushes resolution far higher, which is the central reason different microscopies exist.
Light versus electron microscopy
Light (optical) microscopy uses visible light and glass lenses. It is versatile, can image living cells, and supports techniques such as fluorescence, but its resolution is bounded by the wavelength of light.
Electron microscopy uses a beam of electrons, whose far shorter wavelength gives much higher resolution, revealing structures down to the near-atomic scale. The trade-off is that samples usually must be prepared and viewed under vacuum. The dedicated forms are covered at electron microscopy.
Uses in research
Microscopy is foundational across biology, materials science, and geology. Researchers use light microscopy to study cells and tissues, fluorescence microscopy to localise specific molecules, and electron microscopy to image viruses, macromolecular complexes, and material microstructure. Quantitative imaging increasingly depends on documented acquisition settings and calibrated scale bars so that measurements from images are accurate and reproducible.
Key facts
At a glance
- Definition: magnifying objects too small for the eye
- Two key properties: magnification and resolution
- Resolution limit: set by the wavelength of the radiation
- Light microscopy: uses visible light and glass lenses
- Electron microscopy: uses electron beams for higher resolution
- Light-microscopy limit: roughly 200 nanometres
Common questions
FAQ
What is the difference between magnification and resolution?+
Magnification is how much larger an image appears, while resolution is the smallest distance at which two points can still be distinguished. High magnification without sufficient resolution simply enlarges a blurred image.
Why can electron microscopes see smaller things than light microscopes?+
Resolution is limited by the wavelength of the radiation used. Electrons have a much shorter wavelength than visible light, so electron microscopes can resolve far finer detail, down to the near-atomic scale.
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