OPTICALLY VARIABLE DEVICE (OVD) AND A METHOD OF RECORDING OVD AND AN OVD RECORDER

摘要

In an optically variable device consisting of pixels at least one pixel (1) is a graphical reproduction of a phase of a Fourier transform of a map (M) of viewing angles defined for each such pixel (1). An optically variable device is recorded through illuminating, upon the opening of a shutter (2), with an expanded and convergent beam (L) of laser light, an image (6) of the pixel map, obtained as a graphical reproduction of a phase of the Fourier transform of the map of viewing angles, and the map is then reduced to a desired size with a lens (4). Subsequently, the shutter (2) shuts off the laser light beam (L) and the photosensitive material where an optically variable device is recorded, is moved on to the next pixel with the use of an XY moving stage (5) and the procedure is repeated. A recorder of optically variable devices is provided with an image (6) of the pixel map between an expander (3) of the laser light beam (L) and the lens (4).