People usually associate holograms with futuristic 3-D display technologies, but in reality, holographic technologies are now being used to study materials at the atomic level. X-rays, a high-energy form of light, are often used to study atomic structure. However, X-rays are only sensitive to the number of electrons associated with an atom. This limits the use of X-rays for studying materials made up of lighter elements. Neutron measurements can often fill in the structural gaps when X-ray measurements fail, but neutron beams are harder to produce and have lower intensities than X-ray beams, which limits their versatility.