Diffraktiolauseen

Diffraktiolauseen is a Finnish term that appears in some contexts as a reference to a diffraction theorem or, more generally, to the principles governing diffraction of waves. Diffraction describes how waves bend and spread when they encounter obstacles or pass through openings. In classical wave theory, diffraction is explained by the Huygens–Fresnel principle and can be formulated with the Kirchhoff diffraction integral. In the framework of Fourier optics, a central result is that, in the Fraunhofer (far-field) limit, the observed diffraction pattern on a screen is proportional to the squared magnitude of the Fourier transform of the aperture function. This relationship is often described as a diffraction theorem, because it links the physical shape of an opening to the resulting intensity distribution.

The concept has wide applicability in optics and wave physics, including imaging systems, spectroscopy, microscopy, electron diffraction, and X-ray crystallography. It underpins how lenses, slits, and apertures shape the information carried by waves and how diffraction effects must be accounted for in design and interpretation of experiments.

Note that the exact usage of the term can vary. In Finnish texts, diffraktiolauseen or related forms may be used as shorthand for the broader diffraction theory rather than referring to a single, universally named theorem. Readers encountering the term should verify its precise meaning within the specific source.

See also: diffraction, Huygens–Fresnel principle, Kirchhoff’s diffraction formula, Fraunhofer diffraction, Fourier optics.