Dennis Gabor invented 'holography,' a method of displaying a three-dimensional image of an object by splitting a coherent light beam so that some of it falls on a photographic plate and the rest on the object which reflects back onto the photographic plate.  The two beams form an interference pattern on the plate with alternating light and dark.  "The light is where the two images both relect light back and reinforce each other, while the dark is where the images do not match". The plate is then developed, creating a 'hologram,' Greek for 'completely written.'