Aspheric lens surfaces are used to correct spherical aberration (where the converging light from a lens does not have a common focal point, resulting in a distorted image) in lasers and imaging. Traditional spherical lenses cannot collimate light effectively because even small angles of incidence can produce spherical aberrations. This can mean that several components may be required to get the desired result. The non-spherical surface of an aspheric lens allows a single component to effectively focus or collimate even highly divergent emissions, potentially replacing a multi-lens system with a single aspheric lens.
