In part, the invention relates to methods, systems, and devices that use thermal transients to diagnose wear or other damage in a document such as a banknote. In one embodiment, the invention performs various steps including applying a transient heating or cooling stimulus to the document, wherein the document includes a substrate and a plurality of elements thermally dissimilar to the substrate; detecting a differential thermal emission signature for the substrate and each thermally dissimilar element using a sensor; and determining a wear status of the document based on the detected differential thermal emission signatures.
展开▼