Testing device for displaying hidden diffraction-optical information of e.g. hologram for real time protection of bank note, has illumination sources producing moved image sequence from information of structure by switch on and off

摘要

The device has an illumination mechanism for illuminating a diffraction structure (12) to be tested. The mechanism includes a set of illumination sources aligned to different partial areas of the structure. The sources produce a moved image sequence from hidden diffraction-optical information of the structure by successive switch on and off. The sources are formed by laser sources e.g. laser diode and narrow-band LED. A safety net (20) detects the produced image sequence. A control unit switches on and off the source in a preset sequence. An independent claim is also included for a method for real time testing of a diffraction structure using a testing device.