All-Optical Decoder for Rapid and Noncontact Readout of Thermal Barcodes

An infrared source was used to heat up barcode, and a thermal imager (IR camera) was used to collect thermal images continuously while the barcode was heating up or cooling down. Thermal barcodes that consisted of four types of PCMs were decoded by identifying abrupt changes in temperature profiles during heating (cooling) process. Instead of identifying melting temperatures via direct contact in traditional differential scanning calorimetry, the infrared heating and imaging techniques provide a noncontact and highly sensitive way to characterize material properties and decode thermal barcode at high spatial resolution. (publisher abstract modified)