A security document provided with at least one transparent window (34; 44; 54; 74; 85), obtained using a method including steps of: - arranging between two laminating plates (30, 31; 40, 41; 50, 51; 70, 71; 80, 81) a stack of layers of materials composed of at least one layer (1, 3) opaque to light and at least one layer (2, 4, 5) transparent to light, said opaque layer (1, 3) including at least one orifice (6, 7) intended to form said transparent window of the document; - proceeding with the lamination of the stack of layers (1, 2, 3, 4, 5) between two of said laminating plates by applying to said laminating plates predefined pressure and temperature so as to cause creeping of the material of said at least one transparent layer (2, 4, 5) towards the orifices (6, 7) of said at least one opaque layer (1, 3); - and at least one of the laminating plates (30, 31; 40, 41; 50, 51; 70, 71; 80, 81) including a relief element (32; 42; 52; 72; 82, 83) positioned opposite said orifices (6, 7) and able to push back during lamination a portion of the material of said at least one transparent layer (2, 4, 5) towards said at least one orifice (6, 7) to form a transparent window (34; 44; 54; 74; 85) in the security document; - said relief element (32; 42; 52; 72; 82, 83) having a square, rectangular or cambered cross-section and a volume substantially equivalent to the volume of the orifices (6, 7) to be filled, so as to fill during lamination the volume of the window (34; 44; 54; 74; 85) with the material of said at least one transparent layer (2, 4, 5), characterized in that said transparent window is provided with two convex or concave imprints (86, 87) located opposite one another and configured to generate a magnifying optical effect for a sign, a character or an image arranged on or in said transparent window. - arranging between two laminating plates (30, 31; 40, 41; 50, 51; 70, 71; 80, 81) a stack of layers of materials composed of at least one layer (1, 3) opaque to light and at least one layer (2, 4, 5) transparent to light, said opaque layer (1, 3) including at least one orifice (6, 7) intended to form said transparent window of the document; - proceeding with the lamination of the stack of layers (1, 2, 3, 4, 5) between two of said laminating plates by applying to said laminating plates predefined pressure and temperature so as to cause creeping of the material of said at least one transparent layer (2, 4, 5) towards the orifices (6, 7) of said at least one opaque layer (1, 3); - and at least one of the laminating plates (30, 31; 40, 41; 50, 51; 70, 71; 80, 81) including a relief element (32; 42; 52; 72; 82, 83) positioned opposite said orifices (6, 7) and able to push back during lamination a portion of the material of said at least one transparent layer (2, 4, 5) towards said at least one orifice (6, 7) to form a transparent window (34; 44; 54; 74; 85) in the security document; - said relief element (32; 42; 52; 72; 82, 83) having a square, rectangular or cambered cross-section and a volume substantially equivalent to the volume of the orifices (6, 7) to be filled, so as to fill during lamination the volume of the window (34; 44; 54; 74; 85) with the material of said at least one transparent layer (2, 4, 5), characterized in that said transparent window is provided with two convex or concave imprints (86, 87) located opposite one another and configured to generate a magnifying optical effect for a sign, a character or an image arranged on or in said transparent window.