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

An all-optical decoder was developed for remote rapid readout of the thermal barcode made of solid-to-liquid phase-change materials (PCMs). An infrared source was used to heat up barcode; a thermal imager (IR camera) was used to collect thermal images continuously while the barcode was heating up or cooling down. Thermal barcodes consisting 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.