Editing Specular reflection (section)

{{Short description|Mirror-like wave reflection}}
{{For|the song with identical title|Specular Reflection (song)}}
[[Image:Reflection angles.svg|frame|Coplanar condition of specular reflection, in which <math>\theta _i = \theta _r</math>]]
[[Image:Tso Kiagar Lake Ladakh.jpg|thumb|Reflections on still water are an example of specular reflection.]]

'''Specular reflection''', or '''regular reflection''', is the [[mirror]]-like [[reflection (physics)|reflection]] of [[wave]]s, such as [[light]], from a [[surface]].<ref>{{cite book | chapter = Specularity, Specular Reflectance |title=Computer Vision | last= Tan | first= R.T. | editor-first1= Katsushi | editor-last1= Ikeuchi | publisher = Springer, Boston, MA | year = 2013 | isbn = 978-0-387-31439-6 | doi = 10.1007/978-0-387-31439-6_538 | s2cid= 5058976 }}</ref> 

The '''law of reflection''' states that a reflected [[ray (optics)|ray]] of light emerges from the reflecting surface at the same [[angle]] to the [[surface normal]] as the incident ray, but on the opposing side of the surface normal in the plane formed by the incident and reflected rays. The earliest known description of this behavior was recorded by [[Hero of Alexandria]] ([[Anno Domini|AD]] c. 10–70).<ref>
{{cite book
 |title=A history of Greek mathematics. Volume II: From Aristarchus to Diophantus
 |url={{google books |plainurl=y |id=sl0bUVtZbpEC}}
 |author=Sir Thomas Little Heath
 |isbn=978-0-486-24074-9
 |year=1981
}}</ref> Later, [[Ibn al-Haytham|Alhazen]] gave a complete statement of the law of reflection.<ref>{{cite book |last=Stamnes |first=J. J. |url=https://books.google.com/books?id=dGQ-DwAAQBAJ&dq=alhazen+law+of+reflection&pg=PT15 |title=Waves in Focal Regions: Propagation, Diffraction and Focusing of Light, Sound and Water Waves |date=2017-11-13 |publisher=Routledge |isbn=978-1-351-40468-6 |language=en}}</ref><ref>{{cite book |last=Mach |first=Ernst |url=https://books.google.com/books?id=7dPCAgAAQBAJ&dq=alhazen+incident+ray+reflected+ray+lie+on+same+plane&pg=PA29 |title=The Principles of Physical Optics: An Historical and Philosophical Treatment |date=2013-01-23 |publisher=Courier Corporation |isbn=978-0-486-17347-4 |language=en}}</ref><ref>{{cite book |last=Iizuka |first=Keigo |url=https://books.google.com/books?id=h9n6CAAAQBAJ&dq=alhazen+law+of+reflection&pg=PA7 |title=Engineering Optics |date=2013-11-11 |publisher=Springer Science & Business Media |isbn=978-3-662-07032-1 |language=en}}</ref> He was first to state that the incident ray, the reflected ray, and the normal to the surface all lie in a same plane perpendicular to reflecting plane.<ref>{{cite book |last=Selin |first=Helaine |date=2008 |title=Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures |p=1817 |url=https://www.google.ca/books/edition/Encyclopaedia_of_the_History_of_Science/czFOvQEACAAJ }}</ref><ref>{{cite book |last=Mach |first=Ernst |url=https://books.google.com/books?id=7dPCAgAAQBAJ&dq=alhazen+first+incident+ray+reflected+ray+lie+on+same+plane&pg=PA29 |title=The Principles of Physical Optics: An Historical and Philosophical Treatment |date=2013-01-23 |publisher=Courier Corporation |isbn=978-0-486-17347-4 |language=en}}</ref>

Specular reflection may be contrasted with [[diffuse reflection]], in which light is scattered away from the surface in a range of directions.