Introduction to laser holographic anti-counterfeiting knowledge

Laser anti-counterfeiting basic concept

The laser holographic anti-counterfeiting technology includes three aspects: laser holographic image anti-counterfeiting mark, encrypted laser holographic image anti-counterfeiting mark and laser lithography anti-counterfeiting technology. Holographic anti-counterfeiting technology includes conventional holographic anti-counterfeiting technology, multi-channel holographic anti-counterfeiting technology, stealth encryption technology, 360° computer dot matrix holography technology, double-layer holographic technology, fluorescence encryption holography technology, dynamic coding anti-counterfeiting technology, telephone code anti-counterfeiting technology, nuclear micro-hole Anti-counterfeiting technology and genetic anti-counterfeiting technology, and has the characteristics of clear image, beautiful color, strong stereoscopic effect and one-time use. Multi-channel holographic anti-counterfeiting When you turn the logo, you will see different patterns appearing at the same location of the logo. The stealth encryption technique creates an encrypted pattern at any location of the logo, and an encrypted pattern can be seen under the laser renderer. The 360° computer dot matrix holography technology combines and transforms light spots such as radial, ring, and spiral in the 360° observation range, and the motion is extremely strong. The double-layer holographic technology can uncover the holographic logo, and can also see the second anti-counterfeiting layer printed with patterns and characters, with double-proof anti-counterfeiting effect. The principle of fluorescence encryption holography is the same as that of RMB fluorescence encryption. Dynamic coding anti-counterfeiting is to place the trademark in front of the eyes, and slowly rotate the trademark to appear a continuous motion pattern. The telephone code anti-counterfeiting mark is made up of a combination of laser anti-counterfeiting technology and telephone code anti-counterfeiting technology. The authenticity can be checked by querying the unified central database. The nuclear microporous anti-counterfeiting mark is composed of laser anti-counterfeiting technology and nuclear micro-hole anti-counterfeiting technology, and the authenticity can be distinguished by only one pen. Gene anti-counterfeiting is the addition of genetic factors to the marker backing, which is detected by special instruments.

Commonly used is laser rainbow embossed hologram anti-counterfeiting technology, which is a kind of visual graphic information produced on the product by using laser rainbow hologram plate making technology and mold copying technology.

2. Development history of laser holographic anti-counterfeiting technology

1. The first generation of laser anti-counterfeiting technology

The first generation of laser anti-counterfeiting technology is a laser-molded holographic image anti-counterfeiting mark. The hologram was discovered by the American scientist M. J. Buerger when taking photos of the atomic structure of the crystal using X-rays, and together with D. Gaber established the holographic theory: using double beams The principle of interference allows the object light to be combined with another beam (reference beam) that is coherent with the object light to "merge" the phase so that the photographic image can be simultaneously recorded with the photographic film to obtain a holographic image. However, holograms are taken according to the principle of interferometry and must be recorded with a high density (resolution) photoreceptor. Since the ordinary light source has poor monochromaticity and poor coherence, the development of holography is slow, and it is difficult to take a decent hologram. Until the advent of the laser in the early 1960s, its high brightness, high monochromaticity and high coherence characteristics quickly promoted the development of holographic technology. Many kinds of holograms were produced, and holographic theory was well verified, but due to The special requirements for shooting and reproduction have been almost confined to the laboratory since the day of birth.

In the late 1970s, holograms were found to have surface structures that include three-dimensional information (ie, criss-crossing interference fringes) that can be transferred to materials such as high-density photoreceptors. In 1980, American scientists used embossed holography to transfer the holographic surface structure to the polyester film, successfully printing the world's first molded hologram. This laser hologram is also called the rainbow hologram. Through laser plate making, the image is made on a plastic film to produce a diffractive effect of five colors and light, and the picture has a two-dimensional, three-dimensional sense of space. Under ordinary light, hidden images and information will be reproduced. When the light is illuminated from a certain angle, a new image appears. This molded hologram can be quickly copied in large quantities like printing, at a lower cost, and can be used in combination with various types of printed matter. At this point, holography has taken a decisive step toward social application.

Since the manufacturing technique of this molded hologram was a very advanced technology at that time, only a few people mastered it, and it was used as an anti-counterfeiting mark. The principle of its anti-counterfeiting is:

a. In the whole process of laser hologram shooting, if there is a different condition (such as the condition of shooting rainbow hologram), the effect of holographic logo will be different.

b. The holographic information of such a holographic image cannot be photographed by ordinary photography, and thus the hologram pattern is difficult to be reproduced.

The first to apply a hologram as an anti-counterfeit logo is Johnny Walke Whishy. When it was applied in Thailand, sales were said to have increased by about 45%.

Laser embossed holographic anti-counterfeiting technology was introduced into China in the late 1980s and early 1990s, especially during the period from 1990 to 1994. Hundreds of production lines were introduced across the country, accounting for more than half of the world's manufacturers. In the early stage of introduction, this anti-counterfeiting technology did play a certain role in anti-counterfeiting. However, with the passage of time, laser holographic image production technology spread rapidly. Nowadays, it has been attacked by various counterfeiters and almost lost its anti-counterfeiting ability.

Technical review:

Laser anti-counterfeiting labels have the following inherent defects when they are produced:

a. Just rely on the confidentiality and control of the production technology to prevent forgery.

b. It belongs to the simple observation type anti-counterfeiting technology. The observation point mainly depends on whether it is a holographic image, and the second is to see whether the pattern conforms to the published pattern. However, ordinary consumers can distinguish two different versions of holography only when they are carefully compared. Logo.

c. There is no technical method to prevent the anti-counterfeiting mark itself from being reused.

d. There is no technical method to prevent the packaging with the anti-counterfeiting mark from being reused.

e. There is no technical method to prevent counterfeiters from obtaining anti-counterfeiting marks by means of buying and selling bribes.

2. Improved laser holographic image anti-counterfeiting logo

Since the first generation of laser holographic anti-counterfeiting signs have completely lost their anti-counterfeiting functions, people have to start to improve them. There are three main methods to improve: the first is to use computer technology to improve the holographic image, the second is to develop a transparent laser holographic image anti-counterfeiting mark, and the third is to reflect the laser holographic image security mark.

(1). Improvements in the application of computer image processing technology: Computer image processing technology to improve laser holographic image has undergone two stages of development, the first stage is computer synthetic holography technology, this technology is a series of ordinary two After the optical image is optically imaged, a series of processing is performed according to the principle of the holographic image, and recorded on a holographic recording material to form a computer pixel hologram image. When viewing such a pixel hologram image, the image may be different. The viewing angle sees different three-dimensional images, and its graphics and color have extremely dynamic effects that are extremely flexible and variable, and are not limited by the direction of the reproduced light. The second stage is computer-controlled direct exposure technology. Unlike ordinary holographic imaging, this technology does not require shooting objects. The required graphics are completely generated by the computer. The two coherent beams are controlled by computer to generate all the patterns in pixels by pixel. The point can change the angle between the two beams to create a three-dimensional hologram with special effects.

(2). Transparent laser holographic image anti-counterfeiting technology: Ordinary laser holographic image is molded by aluminum-plated polyester film (also can be firstly molded and then plated with polyester film), and the effect of aluminum plating is Increasing the intensity of the reflected light makes the reproduced image brighter, and both the illumination light and the viewing direction are on the observer side, such a laser rainbow embossed hologram is opaque. The improvement of the transparent laser hologram is actually the elimination of the aluminized layer, and the hologram is directly molded on the transparent polyester film. In 1996, the Ministry of Public Security of China decided to apply the transparent laser rainbow embossed hologram to the resident ID card. The ID card was completely covered and sealed by the transparent film. When observing the front side under the light, not only can the documents be seen, but also See the two-dimensional three-dimensional rainbow holographic image reproduced on the transparent film (Chinese and English in Great Wall and China)

(3). Reflective laser holographic image anti-counterfeiting technology: The reflection hologram is to inject the incident laser onto the transparent holographic latex medium, part of the light is used as the reference light, and 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 to form a multi-layer interference fringe surface inside the medium, and the dielectric film is processed to generate a plurality of semi-transparent reflecting surfaces in the medium (for example, a 6-micron thick latex layer can have more than 20 layers). Reflective surface). The reproduction process of the hologram is to illuminate the hologram with a white light point source, and the multi-layer semi-transparent reflection surface generated inside the medium reflects the light back. When viewed against the reflected light, the virtual image of the original object can be seen, which is called reflection holography. Figure.