Gradient refractive index lens elements

摘要

A lens element (40) is formed from a monolithic unit (46) having two sections (46A and 46B) aligned on an optical axis. A selected one of the sections has an axial gradient refractive index, and the other has a homogeneous refractive index. A first surface 42 is generated one section and a second surface is generated on the other. The axial gradient index material may be selected such that third order spherical aberration of the element is zero. The axial gradient index material may be selected such that similarly constructed elements having shape factors between about 0 and 2.0 also have zero third order spherical aberration. Another element (20) may be formed entirely from an axially graded refractive index material. The refractive index preferably varies as a non-linear function of at least distance along the optical axis. The refractive index function and index change may be selected such that a selected third order aberration is zero or some constant value over a wide range of shape factor. An element (98) is formed from a material having an axial gradient dispersion. Shape factor and dispersion gradient may be selected such that the element is achromatic.