Definitions for "Aspherical"
Not spherical. To reduce spherical aberration, a lens may be altered slightly so that one or more surfaces are aspherical.
adj. A lens element that is not spherical, designed to correct distortion in ultra wide angle lenses and coma in wide aperture lenses. It also has applications in other type of lenses allowing simpler, cheaper, and more compact designs. _______________________________________________________
varying slightly from a perfectly spherical shape