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
<p>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.</p>