Spherical Aberration Correction
The most notable benefit of aspheric lenses is their ability to correct for spherical aberration, an optical effect which causes incident light rays to focus at different points when forming an image, creating a blur. Spherical aberration is commonly seen in spherical lenses, such as plano-convex or double-convex lens shapes, but aspheric lenses focus light to a small point, creating comparatively no blur and improving image quality. Spherical aberration is inherent in the basic shape of a spherical surface and is independent of alignment or manufacturing errors; in other words, a perfectly designed and manufactured spherical lens will still inherently exhibit spherical aberration. An aspheric lens can be designed to minimize aberration by adjusting the conic constant and aspheric coefficients of the curved surface of the lens.