Luneberg Lenses

Rozendal Associates, Inc. manufactures stepped-index Luneberg lenses. Diameters ranging from two (2”) inches to thirty-two (32”) inches are readily available. We also have tooling for manufacturing stepped index lenses up to forty-eight (48”) inches in diameter.

The Luneberg lens is a spherical lens (see diagram) with the property that energy from a feed source at any point on the spherical surface is propagated through the sphere into a plane wave emerging from the other side of the sphere. Plane waves are obtained for all feed positions on the spherical surface.

The focusing properties of the spherically symmetrical general Luneberg lens can be achieved by an infinite number of different relationships between the dielectric constant and radius. The figure illustrates the most common Luneberg lens where one focal point is on the sphere’s surface and the other is at infinity.
The lens is a non-homogenous medium in which the dielectric constant out varies with the lens radius according to the expression E=2-R*R for a unit radius sphere. A smooth variation of dielectric constant with radius is very difficult to achieve, but a satisfactory step-wise approximation can be made. We manufacture a type of hemispherical shell construction that has proven to be very successful; satisfactory performance has been obtained by using a number of hemispherical shells of uniform dielectric material to approximate a continuous gradient of dielectric constant.