An axially symmetric variable-angle non-imaging transformer

The theory of a new kind of non-imaging transformer, with some potentially useful properties, is described. The device is symmetric with respect to rotation about an axis. If the (circular) entrance aperture is uniformly and diffusely illuminated out to a radius r, the exit aperture emits light uniformly within the angle θ to the axis, where sin θ∞r. The device is formed from many thin layers of transparent material which channel the light by (nearly) total internal reflection.