Abstract: The invention is a method and apparatus for the application of machine readable matrix marking symbols, and especially two-dimensional matrix symbols, to a "host" substrate, optionally covering the symbols with protective layers, then using an ultrasound imaging apparatus to capture echo signals associated with the matrix symbols, then feeding the resultant information to a matrix symbol decoder to yield human-readable and video monitor displayable information.

Abstract: The present invention involves enhancing machine-readable matrix symbol markings on substrate materials by the addition of magnetizable materials, and then, at a later time, taking advantage of the magnetic properties associated with the matrix symbol marking to read the marking using a magneto-optic reading apparatus. For example, the marking material may be mixed with a media having magnetic properties and applied to a component surface either via stencil or as backfill. The magnetic material enables detection with the aid of a magnetic-property detection apparatus. Once detected, the matrix symbol image is transmitted to a symbol decoder so that the information represented by the symbol can be provided to a user.