Fresnel number

noun

A dimensionless quantity (denoted F), such that for an electromagnetic wave passing through an aperture and hitting a screen, F=(a²)/(Lλ) where a is the characteristic size (e.g. radius) of the aperture, L is the distance of the screen from the aperture, and λ is the incident wavelength.

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Meanings

nounFresnel number (plural Fresnel numbers)

plural Fresnel numbers

  1. engineeringA dimensionless quantity (denoted F), such that for an electromagnetic wave passing through an aperture and hitting a screen, F=(a²)/(Lλ) where a is the characteristic size (e.g. radius) of the aperture, L is the distance of the screen from the aperture, and λ is the incident wavelength.

Origin

Named after the physicist Augustin-Jean Fresnel.

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Cite this entry
APA

Fresnel number. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/Fresnel%20number

MLA

“Fresnel number.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Fresnel%20number. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “Fresnel number,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/Fresnel%20number.

Source: Fresnel number on Wiktionary, CC BY-SA 4.0.