It is essentially essentially a hologram of a hologram, in which the first-generation hologram is masked with a narrow slit. The rainbow hologram separates out components wavelengths of white light and sends them in different directions, so that the viewer sees the image by light of only one wavelength, the actual wavelength being determined by the viewpoint.

They are made by a double holographic process where an ordinary hologram such as a transmission hologram is used as the object and a second hologram is made through a slit. During image reconstruction, the slit operates and it removes the coherence requirement on the viewing light. This makes it possible to maintain the 3 dimensional character of an image while the viewer moves horizontally. This also maintains the brightness of the image. If the viewers eye is moved vertically, no parallax is seen and the image color sweeps through the rainbow spectrum from blue to red, hence rainbow hologram.

Applications of Rainbow Hologram

• Decorative and product packaging
• Promotional labels
• Gift wraps
• Stickers
• Displays
• Image processing