Aspherical Lens

An aspherical lens is an optical lens whose surface profile is not a portion of a sphere or cylinder. In other words, its curvature changes from the center to the edge, unlike a simple spherical lens which has a constant radius of curvature. In optics, an aspherical surface (or asphere) is any surface that is not a portion of a sphere. While spherical surfaces are defined by a single radius of curvature, aspherical surfaces have a more complex profile, with a radius of curvature that changes from the center of the lens to its edge.