Asphere
/ˈeɪ.sfɪər/noun
A lens, mirror, or optical surface that is not part of a perfect sphere.
Did you know?Aspheric lenses were historically valued because carefully shaped surfaces could correct optical distortions that ordinary spherical lenses could not.
Etymological Timeline
Proto-Indo-European
PIE
*sphē-
“A reconstructed root associated with expansion or swelling; its exact connection to the later Greek word is traditionally proposed but not completely certain.”
Ancient Greek
Greek
σφαῖρα (sphaîra)
“Ball or globe; later, a celestial sphere.”
1st Century BCE
Latin
sphaera
“A ball, globe, or model of the heavens, borrowed from Greek.”
14th Century
Middle English
spere
“A globe, orb, or celestial region, developing into English sphere.”
17th Century
English
sphere
“A round solid figure, globe, or celestial region.”
20th Century
English
asphere
“A technical optical term formed from a- meaning “not” plus sphere, referring to a non-spherical optical surface.”
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