Information coding and retrieving using fluorescent semiconductor nanocrystals for object identification

The spectral features, i.e., wavelength and intensity, of fluorescence generated from semiconductor nanocrystals (quantum dots) can be used for coding information. Unlike the 1-D and 2-D barcodes, the information carrier is applied to a very small area and hardly visible. The information retrieving by a fluorospectrometer is not subjected to the changes of rotation and scale. A de-convolution-based algorithm is used to separate the overlapped spectral profiles. This technology can be applied to small products labeling, document security and object identification.