The second generation of improved laser hologram anti-counterfeiting technology
The flood of the first generation of laser holographic anti-counterfeiting technology makes people have to start to seek to improve the existing technology. There are three kinds of improved technologies: first, the application of computer image processing technology to improve holographic images; Second, the security technology of transparent laser hologram image; Third, the anti - counterfeiting technology of reflected laser hologram image.
A. use computer image processing technology to improve holographic image
Computer image processing technology to improve the laser holographic image has experienced two development form, the first form is computer-generated holographic technology, this technology is a series of ordinary 2 d image after optical imaging, according to the imaging principle of holographic records on a holographic recording materials after processing, forming a computer pixel hologram. When viewing this kind of pixel holographic image, different 3d images can be seen from different perspectives, and its patterns and colors have an unusually flexible dynamic effect, and are not restricted by the direction of reproducing light. Computer control direct exposure technology, the second form is different from ordinary holographic imaging, this technique does not need to the subject, the required computer generated graphics, two beams of coherent beams through computer control in pixels to generate all point-by-point pattern, the difference can change the Angle between the double beam, which is made with special effect of three-dimensional hologram.
2. 2 transparent laser holographic image security technology
Ordinary laser holograms are generally made of aluminized polyester film after molding (or can be molded with polyester film after aluminum plating), aluminum plating is to increase the intensity of reflected light to make the reproduced image more bright. The illumination and direction of view are on the observer side, so the laser rainbow molded hologram is opaque. The transparent laser hologram actually eliminates the aluminized layer and moulds the hologram directly onto the transparent polyester film. In 1996 the Chinese public security department of transparent laser holographic application on the resident identity card, id card with transparent membrane covering whole, id is positive when observed under the light, not only can see the documents content, also can see the transparent membrane appeared 2 d and 3 d rainbow holograms (" Great Wall "and" China "in both Chinese and English words).
3. Counterfeiting technology based on reflecting laser holograms
Reflection principle of laser holographic imaging is the incident laser beam to the transparent holographic emulsion medium, part of the reference light, the other part illuminates the object, through the media by objects scattering medium in the back light again, reference beam and object beams of mutual interference, generated within the dielectric multilayer interference fringe surface, dielectric film after processing the generated within the dielectric multilayer semi-transparent reflective surface (such as 6 microns thick emulsion layer can have more than 20 in the reflecting surface), with a white light point source irradiation hologram, medium generated inside the multilayer semi-transparent reflective surface will be reflected light, against the reflected light can see the virtual image of the original, Therefore, it is called reflected laser hologram.