A pattern of information is detected in a thin-film electrical element including a plurality of thin-film layers on a substrate, the plurality of thin-film layers overlapping in an encoding region to form an optical layer structure. At least one of the thin-film layers in the optical layer structure includes an embedded information-encoding pattern. The thin-film electrical element is illuminated with an incident light beam from a light source thereby producing an optically-detectable interference image including the embedded pattern of information. An image capture system is used to capture an image of the optically-detectable interference image, and a data processing system is used to analyze the captured image to detect the embedded pattern of information. One or more actions are initiated in response to the detected pattern of information.