Lenses with radial gradients can exhibit zero Petzval curvature of field. This class of lens is examined in terms of its other third-order aberrations.
© 1980 Optical Society of America
Duncan T. Moore and Robert T. Salvage, "Radial gradient-index lenses with zero Petzval aberration," Appl. Opt. 19, 1081-1086 (1980)