A system and method for inspecting an article, the system includes a spatial filter that is shaped such as to direct output beams towards predefined locations and an optical beam directing entity, for directing the multiple output beams toward multiple detector arrays. It is a post-compression process for watermarking where no a priori knowledge of the underlying compression algorithm is required. Electrical contact is made with one of the layer of the plurality of graphene layers, so that charge carriers travel only through that one layer. The respective distal ends of the clamping elements may be coupled to activation screws.