A surface relief hologram that comprises two or more patterns, each pattern being sensitive to different radiation wavelengths. The hologram is made by defining relief features that are sensitive to different wavelengths, and in particular to one wavelength that is visible to the unaided human eye and...http://www.google.de/patents/US20050219668?utm_source=gb-gplus-sharePatent US20050219668 - Synthetic colour hologram
