Cladded radially inhomogeneous sphere lenses.

When a radially inhomogeneous sphere is cladded with an additional refractive-index medium, the spherical transverse aberration of a resultant lens is minimized in order to image a point light source in the diffraction-limited spot size for a lens a few millimeters in diameter with ~0.4 N.A. Examples of numerical data used in designing such sphere lenses are given for three different cases: imaging, Fourier transform, and optical disk reading. Various uses of these lenses are also envisioned for demonstrating their potential usefulness.