The two measurements may be used in any manner, e.g. compared to one another, and voids are deemed to be present...http://www.google.fr/patents/US7301619?utm_source=gb-gplus-shareBrevet US7301619 - Evaluating a multi-layered structure for voids Recherche avanc???e dans les brevets Num???ro de publicationUS7301619 B2Type de publicationOctroi Num???ro de demandeUS 11/454,332 Date de publication27 no