An difríocht idir athruithe ar: "Díraonadh"
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Is éard is '''díraonadh''' ann ná iarmhairt trasnaíochta toinne i leith tonnta atá freagrach as leathadh toinne a thagann amach as [[cró]] beag (cosúil le fuaimthonn ag teacht amach as [[callaire]] fógartha poiblí). Trí dhíraonadh a chasann tonnta thar réada, agus is ar an ábhar seo a bhíonn bandaí caola geala is dorcha ar imeall scátha (frainsí díraonta). Is foinse thánaisteach don tonn iomadaithe é an réad díraonta nó an cró. Cheap an t-eolaí Iodálach Francesco Maria Grimaldi an focal ''diffractionem,'' díraonadh (Gaeilge:''briseadh as a chéile'') agus ba é an chéad duine riamh é a thaifead breathnuithe cruinne ar an bhfeiniméan sa bhliain 1660.<ref>Francesco Maria Grimaldi, ''Physico mathesis de lumine, coloribus, et iride, aliisque annexis libri duo'' (Bologna ("Bonomia"), Italy: Vittorio Bonati, 1665), [https://books.google.com/books?id=FzYVAAAAQAAJ&pg=PA2#v=onepage&q&f=false page 2] {{webarchive|url=https://web.archive.org/web/20161201153749/https://books.google.com/books?id=FzYVAAAAQAAJ&pg=PA2|date=2016-12-01}}: <blockquote>''Original'' : Nobis alius quartus modus illuxit, quem nunc proponimus, vocamusque; diffractionem, quia advertimus lumen aliquando diffringi, hoc est partes eius multiplici dissectione separatas per idem tamen medium in diversa ulterius procedere, eo modo, quem mox declarabimus.</blockquote> <blockquote>''Translation'' : It has illuminated for us another, fourth way, which we now make known and call "diffraction" [i.e., shattering], because we sometimes observe light break up; that is, that parts of the compound [i.e., the beam of light], separated by division, advance farther through the medium but in different [directions], as we will soon show.</blockquote></ref><ref>Cajori, Florian [https://archive.org/details/ahistoryphysics00cajogoog/page/n102 <!-- pg=88 quote=Florian Cajori history of physics. --> "A History of Physics in its Elementary Branches, including the evolution of physical laboratories."] {{webarchive|url=https://web.archive.org/web/20161201075614/https://books.google.com/books?id=KZ4C-1CRtYQC&ots=c_YpkkbTpT&dq=Florian%20Cajori%20history%20of%20physics&pg=PA88|date=2016-12-01}} MacMillan Company, New York 1899</ref>
[[File:Single Slit Diffraction.svg|thumb|upright=1.2|Scéimléaráidí agus patrún díraonta don turgnamh aon-scoilt]]
San fhisic chlasaiceach, déantar cur síos ar an bhfeiniméan díraonta leis an b[[Prionsabal Huygens-Fresnel|prionsabal Huygens-Fresnel]] a deir gur féidir breathnú ar gach poncfhoinse ar tonnbhráid mar tonnáin tánaisteacha sféarúla.<ref>Wireless Communications: Principles and Practice, Prentice Hall communications engineering and emerging technologies series, T. S. Rappaport, Prentice Hall, 2002 pg 126</ref> Bíonn an patrún lúbthachta sainiúil níos suntasaí nuair a thagann tonn ó fhoinse chomhleanúnach (ar nós léasair) ar scoilt/cró atá inchomparáide ó thaobh méide de lena thonnfhad,mar a thaispeántar san íomhá ionsáite..nuair a bhuaileann tonn ó fhoinse chomhleanúnach (cosúil le léasair) scoilt/cró atá inchomparáide ó thaobh méide lena thonnfhad, mar a thaispeántar san íomhá a cuireadh isteach. Tá sé seo mar gheall ar phointí éagsúla (nó trasnaíocht) a chur leis ar an tonnbhráid (nó, gach tonnán) a thaistealaíonn ar chonairí ar faid éagsúla go dtí an dromchla clárúcháin. Má tá oscailtí iolracha a bhfuil leagtha amach go dlúth (m.sh., gríl díraonta), is féidir patrún casta déine éagsúil a bheith mar thoradh air.
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