Fresnel number
English
Etymology
Named after the physicist Augustin-Jean Fresnel.
Noun
Fresnel number (plural Fresnel numbers)
- (optics) A dimensionless quantity (denoted ), such that for an electromagnetic wave passing through an aperture and hitting a screen, where is the characteristic size (e.g. radius) of the aperture, is the distance of the screen from the aperture, and is the incident wavelength.