Abstract: The invention relates to a crease-resistant security film including: fibers; polyurethane aggregates, the proportion of said polyurethane amounting to between 5 and 45 wt. % in relation to the total dry weight of the fibers and the polyurethane, and said polyurethane having a break elongation that is higher than 600%; and a main cationic flocculant in a quantity of between 1 and 5 wt. % in relation to the total dry weight of the fibers and the polyurethane. The invention also relates to the method for the production of said film, and to a security document including said security film.

Abstract: The present invention relates to a security element (20) to be built into an item, particularly a document (10), said security element comprising a holographic layer, enabling a volume hologram to be generated, and a non-holographic variable opacity structure generated by the presence of: a) one or more cutout(s) and/or at least partially translucent areas and moreover at least partially opaque area(s); and/or b) oriented platelet pigments. The variable opacity structure is at least partially placed over the hologram within a region of the security element observable in transmitted light.

Abstract: The invention relates to a crease-resistant security film including: fibres; polyurethane aggregates, the proportion of said polyurethane amounting to between 5 and 45 wt. % in relation to the total dry weight of the fibres and the polyurethane, and said polyurethane having a break elongation that is higher than 600%; and a main cationic flocculant in a quantity of between 1 and 5 wt. % in relation to the total dry weight of the fibres and the polyurethane. The invention also relates to the method for the production of said film, and to a security document including said security film.

Abstract: A method and a system for enabling high accuracy measurements to be obtained of the location of a plane separating two media of different densities by using the Compton effect, and application thereof to measuring the thicknesses of layers. A measurement assembly constituted by a transmitter and a receiver of X-rays or gamma rays which are focused in emission and in reception irradiates an elementary volume of said media, and is displaced perpendicularly to the plane between said media, and a fifth signal is calculated representative of the extent by which the derivative of the detected signal relative to the displacement exceeds a threshold, after which the barycenter of displacements corresponding to the most recent sequence of said same-sign fifth signals is calculated, with the displacements being weighted by the corresponding one of said fifth signals.