Luneburg lens
![Cross-section of the standard Luneburg lens, with blue shading proportional to the refractive index](/Images/godic/202501/23/Luneburg_lens.svg4555.png")
![Cross-section of Maxwell's fish-eye lens, with blue shading representing increasing refractive index](/Images/godic/202501/23/Maxwells_fish-eye_lens.svg4555.png")
A Luneburg lens (originally Lüneburg lens, often incorrectly spelled Luneberg lens) is a spherically symmetric gradient-index lens. A typical Luneburg lens's refractive index n decreases radially from the center to the outer surface. They can be made for use with electromagnetic radiation from visible light to radio waves.