Rainbow hologram

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.

This means that only a small horizontal section of the image can be seen from any one location, though if the observer changes his/her viewing position, a different part of the object can be seen.

If the hologram is illuminated with a laser beam of a different wavelength, the position of the reconstructed image will change.

[3] These are used in a wide range of security applications such as credit cards, banknotes and quality merchandise.