Optical security components, manufacture of such components and secure documents equipped with such components

A method for manufacturing an optical security component intended to be viewed in reflection from a viewing face, the method comprising:

• depositing, on a support film, a first layer made of dielectric material, transparent in the visible;
• forming, on said first layer, at least a first diffractive structure,
• depositing a second layer, covering said first diffractive structure at least partially, and having a spectral band of reflection in the visible, wherein:
• said first diffractive structure comprises at least a first pattern consisting of a set of facets arranged to form a plurality of subsets of facets, each subset of facets comprising one or more facets with symmetry of revolution arranged concentrically, said facet(s) of each subset of facets each having a slope with an angular value comprised, in absolute value, between a non-zero minimum angular value and a maximum angular value strictly less than 90°, said facet(s) of each subset of facets each having a given maximum height, a maximum lateral dimension of each subset of facets being smaller than approximately 300 μm;
• in each group of a plurality of groups of subsets of facets, said subsets of facets each present, in a point region defined by an angular sector with polar coordinates comprising an angular coordinate and a radial coordinate which are identical for all subsets of facets of the group, a local alteration of the surface, such as to produce a recognizable graphical object for a given tilt angle and azimuth angle;
• at least said angular coordinate varies from one group to another, in such a way as to produce, when the component is illuminated along a given lighting axis, a dynamic visual effect observable in reflection by a change of azimuth, said dynamic visual effect comprising a movement and/or a deformation of said graphical object.