OPTICAL DECODER FOR THERMAL BARCODES

A high capacity nanoparticle-based covert barcode system relies on an entirely optical readout for detection. The system includes a panel of phase change nanoparticles with sharp and discrete melting peaks; readout is based on heating with an infrared source and detection using an infrared imager, and detection of their phase transition temperatures and positions. A readily detectable and sudden change in temperature occurs at the phase transition during a heating or cooling process, and can be used to indicate the identity of nanoparticles.