Editing Lens (section)

== Non spherical types ==
[[File:Pfeilhöhe.svg|thumb|right|upright|An aspheric biconvex lens.]]
[[Cylindrical lens]]es have curvature along only one axis. They are used to focus light into a line, or to convert the elliptical light from a [[laser diode]] into a round beam. They are also used in motion picture [[anamorphic lens]]es.

[[Aspheric lens]]es have at least one surface that is neither spherical nor cylindrical. The more complicated shapes allow such lenses to form images with less [[Optical aberration|aberration]] than standard simple lenses, but they are more difficult and expensive to produce. These were formerly complex to make and often extremely expensive, but advances in technology have greatly reduced the manufacturing cost for such lenses.

[[File:Flat flexible plastic sheet lens.JPG|thumb|Close-up view of a flat [[Fresnel lens]].]]
A [[Fresnel lens]] has its optical surface broken up into narrow rings, allowing the lens to be much thinner and lighter than conventional lenses. Durable Fresnel lenses can be molded from plastic and are inexpensive.

[[Lenticular lens]]es are arrays of [[microlens]]es that are used in [[lenticular printing]] to make images that have an illusion of depth or that change when viewed from different angles.

[[Bifocal lens]] has two or more, or a graduated, focal lengths ground into the lens.

A [[gradient index lens]] has flat optical surfaces, but has a radial or axial variation in index of refraction that causes light passing through the lens to be focused.

An [[axicon]] has a [[Cone (geometry)|conical]] optical surface. It images a [[point source]] into a line {{em|along}} the [[optic axis]], or transforms a laser beam into a ring.<ref name=Proteep>{{cite web|url=http://www.optics.arizona.edu/OPTI696/2005/axicon_Proteep.pdf |author=Proteep Mallik |title=The Axicon |year=2005 |access-date=22 November 2007 |url-status=dead |archive-url=https://web.archive.org/web/20091123101108/http://www.optics.arizona.edu/OPTI696/2005/axicon_Proteep.pdf |archive-date=23 November 2009 }}</ref>

[[Diffractive optical element]]s can function as lenses.

[[Superlens]]es are made from [[negative index metamaterials]] and claim to produce images at spatial resolutions exceeding the [[diffraction limit]].<ref name=Grbic>{{cite journal
 |last1=Grbic |first1=A.
 |last2=Eleftheriades |first2=G. V.
 |year=2004
 |title=Overcoming the Diffraction Limit with a Planar Left-handed Transmission-line Lens
 |journal= [[Physical Review Letters]]
 |volume=92 |issue=11 |page=117403
 |doi=10.1103/PhysRevLett.92.117403
 |pmid=15089166 |bibcode=2004PhRvL..92k7403G}}</ref> The first superlenses were made in 2004 using such a [[metamaterial]] for microwaves.<ref name=Grbic /> Improved versions have been made by other researchers.<ref name=Valenitne-J.>{{cite journal
 |last1=Valentine |first1=J.
 |year=2008
 |title=Three-dimensional optical metamaterial with a negative refractive index
 |journal=[[Nature (journal)|Nature]]
 |volume=455 |issue=7211 |doi=10.1038/nature07247
 |pmid=18690249
 |bibcode = 2008Natur.455..376V
 |display-authors=1
 |last2=Zhang
 |first2=Shuang
 |last3=Zentgraf
 |first3=Thomas
 |last4=Ulin-Avila
 |first4=Erick
 |last5=Genov
 |first5=Dentcho A.
 |last6=Bartal
 |first6=Guy
 |last7=Zhang
 |first7=Xiang
 |pages=376–9 |s2cid=4314138
 }}</ref><ref>{{Cite journal|last1=Yao|first1=Jie|last2=Liu|first2=Zhaowei|last3=Liu|first3=Yongmin|last4=Wang|first4=Yuan|last5=Sun|first5=Cheng|last6=Bartal|first6=Guy|last7=Stacy|first7=Angelica M.|last8=Zhang|first8=Xiang|date=2008-08-15|title=Optical Negative Refraction in Bulk Metamaterials of Nanowires|journal=Science|language=en|volume=321|issue=5891|pages=930|doi=10.1126/science.1157566|issn=0036-8075|pmid=18703734|bibcode=2008Sci...321..930Y|citeseerx=10.1.1.716.4426|s2cid=20978013}}</ref> {{As of|2014}} the superlens has not yet been demonstrated at [[visible frequency|visible]] or near-[[infrared]] wavelengths.<ref name=mielsen10>{{cite journal|doi=10.1007/s00340-010-4065-z |url=http://cmip.pratt.duke.edu/tomuri2009/sites/cmip.pratt.duke.edu.tomuri2009/files/pubs_purdue/2010_APB_MDC_Superlensing.pdf |title=Toward superlensing with metal–dielectric composites and multilayers |year=2010 |last1=Nielsen |first1=R.B. |last2=Thoreson |first2=M.D. |last3=Chen |first3=W. |last4=Kristensen |first4=A. |last5=Hvam |first5=J.M. |last6=Shalaev |first6=V. M. |last7=Boltasseva |first7=A. |author-link7=Alexandra Boltasseva |journal=Applied Physics B |volume=100 |issue=1 |page=93 |bibcode=2010ApPhB.100...93N |s2cid=39903291 |url-status=dead |archive-url=https://web.archive.org/web/20130309022433/http://cmip.pratt.duke.edu/tomuri2009/sites/cmip.pratt.duke.edu.tomuri2009/files/pubs_purdue/2010_APB_MDC_Superlensing.pdf |archive-date=9 March 2013 }}</ref>

A prototype flat ultrathin lens, with no curvature has been developed.<ref>{{cite journal | title=Good-Bye to Curved Lens: New Lens Is Flat | url=http://www.scientificamerican.com/article/good-bye-to-curved-lens-new-lens-is-flat | access-date=2015-05-16 | first=Prachi | last=Patel | journal=[[Scientific American]] | year=2015 | volume=312 | issue=5 | page=22 | doi=10.1038/scientificamerican0515-22b | pmid=26336702 | archive-date=19 May 2015 | archive-url=https://web.archive.org/web/20150519063304/http://www.scientificamerican.com/article/good-bye-to-curved-lens-new-lens-is-flat/ | url-status=live | url-access=subscription }}</ref>