Security document including patterns with variable optical effect

[0037] Figure 1 to Figure 3 A security credential of a first embodiment of the invention is shown. This security credential is indicated generally by reference numeral 10 .

[0038] In a first embodiment, the voucher 10 is a banknote. In a variant, the document 10 may be a passport, a driver's license or any other document that may need to be secured.

[0039] Voucher 10 includes a substrate 12 made, for example, of a material consisting essentially of plastic, paper, or a mixture of plastic and paper, although the invention is not limited to any particular material. Where appropriate, the material of the substrate may also be a multilayer structure comprising a plurality of layers laminated together.

[0040] The substrate 12 also includes a translucent region 14, which is preferably transparent, and which is referred to as a "window" in the following description. This region 14 is preferably surrounded by an opaque region 16 .

[0041] The presence of such a window 14 in