The development of the hottest laser holography

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The development of laser holography

laser holographic anti-counterfeiting technology is a modern laser application technology achievement that has received widespread attention at home and abroad in recent years. It has won the favor of consumers with its profound holographic imaging principle and colorful flash effect

laser holographic images are also called rainbow and holographic pictures of experimental machines such as leather, paper, rubber, plastic, fiber, etc. laser holographic technology belongs to holographic grating technology in optics. Its products are very different from ordinary photos. It can not only reproduce the main image of the original, but also show the shapes of different sides of the original with different line of sight directions. Laser holograms have been widely concerned and applied in the field of anti-counterfeiting because of their magical colors, realistic images, high information content, and large-scale film pressing replication

laser holographic image anti-counterfeiting technology is to make the image on the plastic film through laser plate making, resulting in colorful diffraction effect. And make the picture have a sense of two-dimensional and three-dimensional space. Under ordinary light, hidden images and information will reappear. When the light shines at a certain angle, a new image will appear. This kind of embossed hologram can be copied in large quantities as quickly as printing, with low cost, and can be used in combination with various printing technologies

this laser anti-counterfeiting logo has congenital defects in its initial stage: it only relies on the confidentiality and control of production technology to prevent counterfeiting; It belongs to simple observation anti-counterfeiting technology. Its observation point is mainly to see whether it is a holographic image, and then to see whether the pattern conforms to the published pattern. However, ordinary consumers can distinguish two different versions of holographic signs only when they carefully compare them; There is no technical method to prevent the anti-counterfeiting logo itself from being reused; There is no technical method to prevent the packaging with anti-counterfeiting marks from being reused; There is no technical method to prevent counterfeiters from using bribes, bribes and other means to obtain anti-counterfeiting marks

when the laser embossing holographic anti-counterfeiting technology was introduced into China in large quantities in the late 1980s and early 1990s, hundreds of production lines were introduced across the country, accounting for more than half of the world's manufacturers at that time. Although this anti-counterfeiting technology did play a certain anti-counterfeiting role in the early stage of introduction, with the passage of time, the laser holographic image making technology has spread rapidly, and now it has been broken by counterfeiters in all aspects, almost completely losing the anti-counterfeiting effect

therefore, on this basis, there are holographic images improved by computer technology, transparent laser holographic image anti-counterfeiting marks and reflected laser holographic image anti-counterfeiting marks

improvement of computer image processing technology laser holography has experienced two development forms. The first form is computer synthetic holography. This technology is to record a series of ordinary two-dimensional images on a holographic recording material after optical imaging according to the imaging principle of holographic images, so as to form a computer pixel holographic image. When observing this kind of pixel hologram, you can see different three-dimensional images from different perspectives. Its graphics and colors have extremely flexible dynamic effects, and are not limited by the direction of the reconstructed light. The second form is computer-controlled direct exposure technology. Unlike ordinary holographic imaging, this technology does not require the subject to be photographed, and the required graphics are completely generated by the computer. The computer controls two coherent beams to generate all patterns point by point in the unit of pixels. The included angle between the two beams can be changed for different points, so as to make a three-dimensional hologram with special effects

ordinary laser holograms are generally made of aluminized polyester film through molding (or polyester film can be molded first and then aluminized). The function of aluminizing is to increase the intensity of reflected light and make the reproduced image brighter. The illumination light and observation direction are on the side of the observer, so the laser rainbow molded hologram is opaque. The transparent laser hologram actually cancels the aluminum coating and directly molds the hologram on the transparent polyester film

the principle of reflection laser holographic image imaging is to shoot the incident laser onto the transparent holographic emulsion medium, one part of the reflected light is used as the reference light, the other part illuminates the object through the medium, and then the object is scattered back to the medium as the object light. The object light and the reference light interfere with each other, and a multi-layer interference fringe surface is generated inside the medium, After the processing of the medium negative, a multi-layer translucent reflecting surface is generated inside the medium (for example, there can be more than 20 reflecting surfaces in the 6 micron thick latex layer), and the hologram is illuminated with a white light point light source. The multi-layer translucent reflecting surface generated inside the medium reflects the light back, and the virtual image of the original object can be seen against the reflected light, so it is called a reflected laser hologram. But these improvements do not change the inherent shortcomings of this technology in essence

the encryption holographic image anti-counterfeiting technology is a more advanced technology than the laser holographic image anti-counterfeiting identification technology. The encrypted holographic image adopts optical image coding encryption technology such as random phase coding image encryption, moire coding image encryption, laser speckle image encryption, which encrypts the anti-counterfeiting image and obtains the invisible or some speckle encrypted image. The image encrypted by random phase encoding is invisible, and the original image can be displayed only by using a special photoelectric decoder

although this image encryption technology requires special instruments to display, it is easy to imitate in today's high-tech and international society. Because when consumers buy goods, they get not only anti-counterfeiting marks containing encrypted images, but also decoding gratings or decoding speckle used to verify the authenticity. In this way, image encryption has no role in anti-counterfeiting at all. The anti-counterfeiting of this anti-counterfeiting logo depends entirely on the difficulty of mastering the manufacturing technology of encrypted images, but mastering this technology is not very difficult. Therefore, this anti-counterfeiting technology also has shortcomings

the latest anti-counterfeiting technology is to present hidden images from holograms

it is a new anti-counterfeiting technology formed by letterpress Co., Ltd. using the "scheme" of electron beam technology (EB) and the silver white holographic anti-counterfeiting technology that the company and new products are increasingly entering the market in 1994 (usually the silver white of hologram will change color with different observation angles, and this silver white hologram is fixed as silver white from any angle). This technology retains the dazzling visual effect of the original silver white holographic technology. When a special simple detector is used to detect it, the hidden code image in the hologram is immediately presented in front of you. Images hidden in high-precision images and observed by detection devices can be continuous, multi picture images stored in any position, which is the first in the world, with high anti-counterfeiting effect and easy detection. Hidden images can be made on the linear and striped holographic films that often appear in gift certificates, stocks and other securities (intellectual property rights include 7 special clearance oil spill excess interest applications)

with the continuous innovation and development of holographic technology, many new technologies based on holograms have emerged, such as dynamic holographic technology, 2D/3D technology, dot matrix holographic technology, micro encryption technology, synthetic encryption technology, photochemical relief technology, machine recognition information technology and so on. This makes holographic anti-counterfeiting technology have the characteristics of first-line anti-counterfeiting and second-line anti-counterfeiting. It is believed that holographic technology will become one of the most widely used anti-counterfeiting technologies with the strongest anti-counterfeiting strength, and will be widely used in the field of printing and packaging with its unique artistic effect and anti-counterfeiting performance. (Wang Rui)

information source: Printing Technology

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