Patent ID: 7905422

Claim:
A flat security element, having a front side and a reverse side, and being relatively small in size, such as planchettes, wherein the element includes an in-register authentication pattern comprising at least one of (i) a combination and (ii) a superposition of a front side pattern on its front side and of a reverse side pattern on its reverse side, wherein each of said front side and reverse side patterns is at least partly observable in transmitted light, wherein said front side pattern is in the form of a front side geometric pattern and said reverse side pattern is in the form of a reverse side geometric pattern, wherein a registration of the in-register authentication pattern is characterized by at least one of (a) said in-register authentication pattern is in register with respect to at least one portion of the shape of said security element, and (b) at least one portion of said front side and reverse side patterns is in register with respect to at least one portion of the other of said front side and reverse side patterns, wherein the registration of said authentication pattern is observable in transmitted light from the front side and from the reverse side of the security element.