A single-element photographic lens was designed to be constructed with a radial gradient-index function. The lens in an ƒ/6.3 version is corrected for spherical aberration, coma, tangential, and sagittal curvature with a 25° half-field, the aberrations being defined as total, rather than third order, fifth order, etc. The performance of the lens roughly matches that of optimal homogeneous lenses, of the same general type, operating at ƒ/11.
E. W. Marchand and D. J. Janeczko, "Design of gradient-index singlets," J. Opt. Soc. Am. 64, 846-849 (1974)