In 1968 Stephen A. Benton, then of Polaroid Corporation, and later at MIT's Media Lab, invented the Benton hologram or rainbow hologram, a hologram designed to be viewed under white light illumation rather than laser light, which was required to view holograms before this invention.
"The rainbow holography recording process uses a horizontal slit to eliminate vertical parallax in the output image, greatly reducing spectral blur while preserving three-dimensionality for most observers. A viewer moving up or down in front of a rainbow hologram sees changing spectral colors rather than different vertical perspectives. Stereopsis and horizontal motion parallax, two relatively powerful cues to depth, are preserved. The holograms found on credit cards are examples of rainbow holograms" (Wikipedia article on rainbow hologram, accessed 11-23-2012).