MEHRSCHICHTIGER, KARTENFÖRMIGER DATENTRÄGER UND VERFAHREN ZUR HERSTELLUNG DESSELBEN

摘要

In a multi-layer card-shaped data storage medium having a layer which appears black in the visible wavelength range but is transparent to test rays in the invisible wavelength range, markings masked by the layer appearing black are provided which are generated by means of a laser beam writer in or underneath the black layer. ……