The invention concerns the constitution of security elements with optical diffraction effect, and a device for controlling such elements. The use of holograms and other security elements with optical diffraction effect for protecting documents and other valuable papers, as well as bank notes against forgery is becoming more and more frequent presently. The element with optical diffraction effect comprises a discontinuous metal coating and/or partial metal coats and/or metal coat zones in different planes, representing an electric data coding, corresponding to the objective. The device comprises a scanner with capacitive functioning. Said scanner consists of a plurality of emitting electrodes placed side by side and a receiving electrode extending parallel to said emitting electrodes arrangement.