Aspheric lens

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An aspheric biconvex lens.

An aspheric lens or asphere is a lens whose surfaces have a profile that is neither a portion of a sphere nor of a circular cylinder. In photography, a lens assembly that includes an aspheric element is often called an aspherical lens.

The asphere's more complex surface profile can eliminate spherical aberration and reduce other optical aberrations compared to a simple lens. A single aspheric lens can often replace a much more complex multi-lens system. The resulting device is smaller and lighter, and possibly cheaper than the multi-lens design. Aspheric elements are used in the design of multi-element wide-angle and fast normal lenses to reduce aberrations.

Aspheric lenses are also sometimes used for eyeglasses. These are typically designed to give a thinner lens, and also distort the viewer's eyes less as seen by other people, producing better aesthetic appearance.^[1] Aspheric eyeglass lenses typically do not provide better vision than standard "best form" lenses, but rather allow a thinner, flatter lens to be made without compromising the optical performance.