Optical Product and Document Security Method

An inexpensive security method for uniquely marking and identifying physical objects such as documents or labels has been developed. This technology uses the mixing of inks in numerous different ratios to print arbitrary marks on a given object. The ink mixture used in a printed mark produces a unique, nonlinear spectral response or pattern upon its optical excitation. This spectral pattern can then be easily measured for authentication of the object, but cannot be replicated by a counterfeiter without a specific information key, which is knowledge of exactly what inks are used and their original mixing ratios.