Abstract: A method of inserting guilloche patterns in a document, each guilloche pattern being capable of encoding variable alphanumeric data ensuring a different aspect at each guilloche pattern so as to render said document secure using an operation of determining an insertion intensity of each guilloche pattern previously generated on the basis of a mid-gray level of the document near said guilloche pattern. A device for implementing this insertion method. The method further provides for extracting guilloche patterns from a secure document likely to be degraded by determining a contrast card of at least one portion of the secure document that includes the guilloche patterns, identifying, on this contrast card an optimal percolation trajectory, and extracting the optimal percolation trajectory, said trajectory corresponding to the guilloche pattern.

Abstract: A method of inserting guilloche patterns in a document, each guilloche pattern being capable of encoding variable alphanumeric data ensuring a different aspect at each guilloche pattern so as to render said document secure using an operation of determining an insertion intensity of each guilloche pattern previously generated on the basis of a mid-gray level of the document near said guilloche pattern. A device for implementing this insertion method. The method further provides for extracting guilloche patterns from a secure document likely to be degraded by determining a contrast card of at least one portion of the secure document that includes the guilloche patterns, identifying, on this contrast card an optimal percolation trajectory, and extracting the optimal percolation trajectory, said trajectory corresponding to the guilloche pattern.

Abstract: A method for marking a surface by controlled periodic nanostructures includes: a step (500) of coding an item of information in the form of an image including values representative of the coded information and a step (506 to 514) of marking, dot by dot, an area of the surface with a polarized laser beam to form oriented nanostructures on or in the surface, by modulating the laser beam's polarization for each marking dot according to the value of a dot of the image. In embodiments, during the marking step, a pulsed laser is utilized with a duration of less than 10×10?12 seconds and an element of polarizing the light coming from the laser source and reaching the surface, designed to polarize the light according to a polarization axis that can vary according to a signal received by the polarization element, is utilized.

Abstract: A method for marking a surface by controlled periodic nanostructures includes: a step (500) of coding an item of information in the form of an image including values representative of the coded information and a step (506 to 514) of marking, dot by dot, an area of the surface with a polarized laser beam to form oriented nanostructures on or in the surface, by modulating the laser beam's polarization for each marking dot according to the value of a dot of the image. In embodiments, during the marking step, a pulsed laser is utilized with a duration of less than 10×10?12 seconds and an element of polarizing the light coming from the laser source and reaching the surface, designed to polarize the light according to a polarization axis that can vary according to a signal received by the polarization element, is utilized.