Lensa utawa uga diarani Kanta yaiku siji srana kang awujud kaca bening gepeng kang duwé sisih-sisih kang simetris. Lensa mono duwé kagunan kanggo ngumpulake cahya marang siji titik utawa malah nyebarake cahya kang liwat ing tengahé. Lensa sepisanan dipangerteni saka catatan sandiwara Yunani Kuno liwat cathetane Aristhophane The Clouds (424 SM) kang mratélakaké anané istilah gelas-gelas pembakar (lensa cembung kang kanggo mokusake sinaring srengéngé kanggo nyipta geni) ing karyané.
Wong kang nemu téyori babagan lensa sepisanan tur uga mratelakake kadadéan bayangan ana ing retina yaiku  fisikawan muslim saka Arab kang asmane Alhazen (Abu Ali al-Hasan Ibn Al-Haitham)

Jinising Lènsa
Lensa kapérang dadi manéka jinis. Lensa bisa dibédakaké saka wujud sisih-sisine. Kontruksi lensa kang paling umum tinemu yaiku lensa speris, yaiku lensa kang sudut mlengkung lumah bidange dibandingake karo radius speris. Titikan radius kang digunakaké dilambangake kanthi lambang R,kang bakal duwé nile positif nalika saben sisine mlengkung ngadohi titik pusere lensa,lan sinebut antarmuka cembung.

Kontruksi
Kontruksi lensa kang paling akèh yaiku kang awujud lensa speris, yaiku lensa kang duwé  babagan speris (mlengkung),notasi kang digunakaké yaiku R.

Réferènsi

Pranala njaba 

 Lens article at digitalartform.com 
 Thin Lens Java applet
 Article on Ancient Egyptian lenses
 Lighthouse Getaway: Fresnel lens (contains photographs.)
 
 Random Destructive Acts via Focused Solar Radiation.
 TruckView Fresnel lens combats the HGV Blind-Spot. 
 How the Fresnel lens works.
 A computer analysis of the Fresnel lens cross section depicted in the 'graphic examples' section of this very Wikipedia article. 
 Applied photographic optics Book
 Book- The properties of optical glass
 Handbook of Ceramics, Glasses, and Diamonds
 Optical glass construction 
 History of Optics (audio mp3) by Simon Schaffer, Professor in History and Philosophy of Science at the University of Cambridge, Jim Bennett, Director of the Museum of the History of Science at the University of Oxford and Emily Winterburn, Curator of Astronomy at the National Maritime Museum (recorded by the BBC).
 a chapter from an online textbook on refraction and lenses 
 Thin Spherical Lenses  on Project PHYSNET.
 Lens article at digitalartform.com 
 Article on Ancient Egyptian lenses
 picture of the Ninive rock crystal lens
 Do Sensors “Outresolve” Lenses? ; on lens and sensor resolution interaction.

Piranti