The invention relates to an application and a method for checking documents. Hitherto, documents with optical diffraction security layers, specially holograms, were checked by costly optical monitoring technology. The entire monitoring process was so time-consuming that the monitoring process could not be applied to fast operating processing machines. Rapid monitoring (as an authentication characteristic) constitutes a further security step in evaluating effective optical diffraction security layers. The effective optical diffraction layer has a discontinuous metallizing layer and/or partially metal layers and/or areas of metal layers on various planes. Several methods of measurement exist to detect electrical conductivity. In practice, the contactless capacitive method of measurement has proven to be more practical.