New optical security device based on one-hundred-year-old photographic technique

A new optical security application of an old color photographic technique (Lippmann photography, invented in 1891) is presented. Today, this type of photography can be applied as a unique security device on security documents, such as, e.g., identification cards, passports, credit cards, and other documents where a high degree of security is needed. A Lippmann photograph is very similar to the holograms currently used in this field; however, a unique recording of each document can be made to achieve a degree of security higher than that with mass-produced holograms. The recording of Lippmann photographs requires a special type of photosensitive medium in contact with a reflecting layer. Panchromatic photopolymer materials can be used and, after being recorded and processed, laminated to security documents. A special type of recording equipment is required. Lippmann photographs are virtually impossible to copy and, certainly, cannot be copied by conventional photography or color copying machines.