Security document including a transparent window formed in the substrate thereof

A security document comprising:

• a substrate having a transparent window formed in the substrate;
• a micro-optical structure composed of microlenses being arranged on a first side of the substrate, at least in a region of the transparent window, and a first print image being arranged on a second side of the substrate, located opposite the micro-optical structure, at least in the region of the transparent window;
• the first print image including a plurality of image elements in a punctiform or linear grid;
• a dot size or a line thickness of the image elements being smaller than a lens width of the microlenses arranged in the micro-optical structure;
• a layer being arranged on and covering a part of the first print image, on a side of the first print image facing away from the micro-optical structure;
• and
• a second print image being arranged on the layer covering the part of the first print image, on a side of the layer facing away from the micro-optical structure,
• wherein the second print image is arranged on the layer covering the part of the first print image in such a way that the second print image can be brought into alignment with the micro-optical structure arranged on the first side of the substrate after carrying out a folding process at a bending line, in such a way that the second print image, or at least a piece of information contained therein, becomes visible and/or recognizable when viewed through the micro-optical structure, and
• wherein:
• the micro-optical structure is designed as a lens array or as a lenticular lens,
• the lens array or the lenticular lens is composed of plano-convex microlenses,
• when the micro-optical structure is the lens array, the plano-convex microlenses have at least one of a rotationally symmetric, spheric, or aspheric configuration, and
• when the micro-optical structure is the lenticular lens, the plano-convex microlenses have an axially symmetric, rod-shaped configuration.