Patent ID: 7537161
Filing Date: 2009-05-26
Classification: B42D,G07D

Abstract:
1. Method for authenticity testing a security element on the basis of liquid-crystalline materials, the security element having at least one first marking with right-handed circularly polarizing liquid-crystalline material and at least one second marking with left-handed circularly polarizing liquid-crystalline material, or having only one marking which contains both right-handed and left-handed circularly polarizing liquid-crystalline material, the method comprising: filtering the light impinging on the security element or the light reflected by the security element by means of a first circular polarizer for a first polarization direction, recording a first image of the security element and determining respective intensity values, filtering the light impinging on the security element or the light reflected by the security element by means of a second circular polarizer for a second polarization direction, recording a second image of the security element and determining respective intensity values, determining a differential image from the first and second image by subtracting an intensity value of a partial area of the first image from a respective intensity value of a corresponding partial area of the second image, and deriving a statement about the authenticity of the security element on the basis of the differential image.