Equation 7 · Part 1 · How Scientific Instruments and Metrology Actually Work
Symbol λ
What this part means
the wavelength of the illuminating radiation, and n is the numerical aperture of the imaging system.
Its job in the formula
λ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol λ→Article meaning
Where the article explains it
where is the wavelength of the illuminating radiation, and n is the numerical aperture of the imaging system.
The passage around this formula
where is the wavelength of the illuminating radiation, and n is the numerical aperture of the imaging system. For visible light this caps optical microscopy at roughly 200 nanometres — far too coarse to resolve individual atoms, whose spacing in a solid is typically a few tenths of a nanometre. Electron microscopy exploits the far shorter de Broglie wavelength of accelerated electrons — picometre scale at typical accelerating voltages — to push the diffraction limit itself down by more than three orders of magnitude.
Learn the underlying idea
A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
Open the illustrated variables: a letter stands for a value guide →
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Sources cited in the article section
- [8] Imaging single atoms using secondary electrons with an aberration-corrected electron microscope ↗
- [7] Electron ptychography of 2D materials to deep sub-ångström resolution ↗
These citations provide research context; check each source for the exact claim it supports.