According to a first aspect, the invention relates to an optical security component intended to be observed in reflection, with the naked eye, according to face of observation. It comprises a first layer made of dielectric material, having a first refractive index (n1), at least one first diffractive structure (S1, S2) etched on said first layer. The first diffractive structure comprises a first pattern with at least one set of modules disposed side-by-side, in a given direction (X) of arrangement, a maximum width (l) of each module defined in the direction of arrangement (X) being less than 300 μm. Each module comprises a bas-relief with a first set of facets whose forms are determined to simulate an optical element visible in reflection, with at least one convex or concave region, said optical element having a profile with a continuously variable slope in a single direction (Y), said direction of variation of the slope, at right angles to the direction of arrangement (X). For two modules side-by-side, the slope along at least one line parallel to the direction (X) of arrangement is different between said two modules.