The principle of laser anti-counterfeiting??

2018-08-14 18:04:14 浏览次数:219

Laser security, also known as laser security

Laser 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.

The rainbow hologram is a rainbow hologram made by a series of programs using a universal holographic image as a subject. For example, a photo-sensitive etch resist is used instead of a hologram taken by an ordinary photo, and after exposure processing, an embossed phase hologram is obtained, that is, a master for making a rainbow hologram. The surface of the master is filled with rugged interference fringes with a fineness of more than a thousand. These embossed stripes record the light intensity and phase information of the object being photographed, realizing holographic recording. Then, a thin metal film is plated on the surface of the master by vacuum plating or chemical plating, and then nickel or other metal of appropriate thickness is electroplated to form a molded metal plate with good mechanical properties. The plate is mounted on a stamping machine, the polyester plastic film is hot pressed, the embossed hologram is embossed on the film, and finally an aluminum film is vacuum-deposited on the film to increase the reflectivity of the film. After the aluminum film is plated or coated with a protective layer, a hologram is formed, that is, an opaque laser-molded holographic anti-counterfeit image. Such holograms can be observed with daylight, and light of each wavelength in daylight is diffracted by interference fringes on the picture. Since there are different diffraction angles, there are different colors of reproduced images when viewed at different angles.

Since the color block combination in the hologram is randomly coded, even if the same device is difficult to produce an identical holographic master, the rainbow hologram image has been widely used for making an anti-counterfeit mark. Holograms can also be transferred directly to paper products and are now widely used in tickets, trademarks and credit cards.

The color of the embossed holographic anti-counterfeiting logo has a single rainbow, a variety of rainbow colors, true colors and black and white (achromatic), and its images are 2D, 3D, multiple and dynamic imaging.

Laser embossed holographic anti-counterfeiting logo hologram imaging technology can be divided into classic, pulsed three-dimensional laser embossed holographic anti-counterfeiting logo and synthetic molding, multiple image laser molding, dynamic molding, dynamic grating molding, invisible holographic molding, anti-counterfeiting ink encryption laser Holographic anti-counterfeiting mark such as molding.

In recent years, there have been bronzing holograms and transmissive holograms, all of which are based on the innovation of ordinary rainbow holograms. The semi-transparent hologram is formed by making the aluminum layer on the polyester film into a dot shape and controlling the density of the dot. Under the reproducing light, light is reflected at the metal dot, and the light transmission is formed at the non-metal dot and adjusted. The ratio of transmission to reflection allows the hologram to pass through while obscuring the image under the picture, so it is also called a see-through hologram.

The development of anti-counterfeiting technology, color holograms, synthetic holograms, cryptographic holograms (using a laser pointer to read the information in the map) and so on. These new packaging materials with anti-counterfeiting function and high-tech holographic image marking technology processed by laser holography have better anti-counterfeiting functions.

The use of holographic printing technology to make anti-counterfeiting marks, attached to the surface of the packaging is currently the most popular anti-counterfeiting means. The holographic image combines the latest achievements in laser, precision machinery and physical chemistry, and has a high technical content. For most small batch counterfeiters, the mastery of manufacturing technology and the purchase of manufacturing equipment are difficult to achieve, so the effect of this technology is significant.

The widespread use of holographic anti-counterfeiting technology and the emergence of other anti-counterfeiting technologies, people have different opinions on holographic anti-counterfeiting, and have many concerns. At present, there are hundreds of manufacturers that can produce such signs. Due to many problems in technology and management, some real marks are not easy to identify, and some of the simulated signs can be faked, which greatly reduces the laser holographic anti-counterfeiting mark in people. The original position in mind. Too many manufacturers, over-products and excessive competition may be the primary reasons for the holographic anti-counterfeiting crisis. However, from a purely technical point of view, the image source is simple, the photo technology is old and the recording material is single, which is also the root cause of the trust crisis. Therefore, if we can strengthen management, improve technology, produce high-quality 3D holograms, and constantly tap, improve and innovate in display, photographic technology and recording materials, grasp holography and other anti-counterfeiting technologies, holographic and printing The combination of holographic and packaging development direction, laser holographic anti-counterfeiting as the main direction of technology development, this is crucial.

Here is a brief introduction to the history of laser anti-counterfeiting technology:

The first generation of laser anti-counterfeiting technology is an anti-counterfeiting mark for laser-molded holographic images.

Holography was discovered by American scientist Mj Buerger when photographing the atomic structure of the crystal using X-rays, and together with D. Gaber established the holographic theory: using the principle of two-beam interference, The illuminating image can be obtained by combining the object light with another beam of light (reference beam) that is coherent with the object light to "merge" the phase so that the photographic phase can simultaneously record the lower phase and amplitude. However, holograms are taken according to the principle of interferometry and must be recorded with high density (resolution) photographic film. Since the ordinary light source has poor monochromaticity and poor coherence, the holographic technology develops slowly, 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:

1. 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.

2. 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 JohnnyWalkeWhishy (a whiskey). 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. At the beginning of the introduction, this anti-counterfeiting technology did play a certain role in anti-counterfeiting. However, with the passage of time, the laser holographic image production technology spread rapidly. Nowadays, the counterfeiters have already broken through all aspects and almost completely lost the ability of anti-counterfeiting.

The second generation of improved laser holographic image anti-counterfeiting technology

The proliferation of the first generation of laser holographic anti-counterfeiting technology has prompted people to begin to seek to improve existing technology. There are three main improvements: one is the application of computer image processing technology to improve holographic images; the second is transparent laser holographic image anti-counterfeiting technology; the third is reflective laser holographic image anti-counterfeiting technology.

1. Apply computer image processing technology to improve holographic images

Computer Image Processing Technology Improvement Laser holography has undergone two developmental forms. The first form is computer-generated holographic technology. This technique is to optically image a series of ordinary two-dimensional images and process them according to the imaging principle of holographic images. A holographic recording material forms a computer pixel holographic image. When observing such a pixel holographic image, different three-dimensional images can be seen at different viewing angles, and the graphics and colors have an extremely flexible and dynamic effect, and are not limited by the direction of the reproduced light. The second form is a computer-controlled direct exposure technique. Unlike ordinary holographic imaging, this technique does not require a subject to be photographed. The required graphics are completely generated by a computer. The two coherent beams are controlled by a computer to generate all the patterns point by point in units of pixels. Different points 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 images are generally molded by aluminized polyester film (which can also be molded and then aluminized with a polyester film). The effect of aluminizing is to increase the intensity of the reflected light to make the reproduced image brighter. Both the illumination light and the viewing direction are on the observer side, such a laser rainbow embossed hologram is opaque. The transparent laser holographic image actually eliminates the aluminized layer and directly molds the holographic image onto the transparent polyester film. In 1996, the Ministry of Public Security of China applied transparent laser holographic images to the resident ID card, and covered the ID card with a transparent film. When observing the front of the ID card under the light, not only can the contents of the certificate be seen, but also the transparent film can be seen. Two-dimensional, three-dimensional rainbow holographic images (Chinese and English characters for "Great Wall" and "China").

3. Reflective laser holographic image anti-counterfeiting technology

The principle of reflective laser holographic image imaging is to project incident laser light onto a transparent holographic latex medium, some of which is used as reference light, and another part illuminates the object through the medium, and then the object is scattered back to the medium as object light, and the object light and the reference light are mutually Interference, a multi-layer interference fringe surface is generated inside the medium, and the dielectric film is processed to generate a plurality of semi-transparent reflecting surfaces in the medium (for example, there may be more than 20 reflecting surfaces in a 6-micron-thick latex layer), and is irradiated with a white light source. Hologram, the multi-layer semi-transparent reflecting surface generated inside the medium reflects the light back, and can see the virtual image of the original against the reflected light, so it is called a reflected laser hologram.

Third generation encryption holographic image anti-counterfeiting technology

Encrypted holographic image refers to the invisible or some speckle encryption obtained by encrypting the anti-counterfeit image by optical image encoding and encryption technology such as laser reading, optical micro-deflification, low-frequency lithography, random interference fringes, moiré fringes, etc. image.

Laser reading

Text or image information is stored in a holographic image using the principle of optical conjugation. In normal circumstances, this information does not appear. When illuminated with a laser pointer, people can see the stored information by means of sulfuric acid paper or white paper. The stored information can be text, logo, grayscale image, or even an article. The expressions are also reflective and transmissive.

2. Optical reduction

The text information is recorded on the hologram by optical micro-constriction, which is difficult to be recognized by the naked eye. The specific content can be observed under the magnifying glass of 10 times or even 100 times. Under normal circumstances, the Chinese can be reduced to 0.1 mm, and the English can be reduced to 0.05mm

3. Low frequency lithography

The pre-designed stripe patterns are directly recorded on the hologram in a microscopic form on the hologram. The stripe density of these patterns is 10 times lower than the normal interference fringe at about 100 lines/mm, and the visual effect is in the hologram. Some parts of the figure have diffraction patterns similar to metallic luster. If the strip pattern is a computer generated hologram, the information can be reproduced by laser.

4. Random interference fringes

Introducing a random mechanism in the production of holograms, recording random interference patterns on holograms, which have obvious features and are not repeatable, even if the same person uses the same process to produce different patterns at different times, so It is a good anti-counterfeiting method. In addition to static plane interference fringes, dynamic, three-dimensional interference fringes have been developed, and counterfeiters cannot replicate at all.

5. Mohr interference encryption

Using the Mohr principle, that is, the overlapping of the stripes of two sets of periodic structures can produce the principle of the third set of periodic structure patterns, in which a set of stripes changes its phase and encodes a pattern, which is hidden and cannot be distinguished in peacetime. The pattern appears when it overlaps with another set of periodic stripes.

Encrypted holographic images have a certain anti-counterfeiting function because they are invisible or only show a piece of noise, such as no key is difficult to decipher. But because it can't be distinguished in the normal environment, it does not have the ability to be recognized by the general public.

The fourth generation laser holographic anti-counterfeiting technology

Combined hologram

A combined hologram is a hologram recorded by tens or even hundreds of different two-dimensional images through tens or even hundreds of exposures. The effect can be embodied in two aspects. One is similar to the plane dynamic design, which can shoot the plane dynamic change pattern of various patterns, and the other is to use 3D software or digital camera to change the various sides of the three-dimensional object and the process with time. Recording, making a four-dimensional hologram, that is, the hologram can not only record and reproduce the three-dimensional (X, Y, Z) characteristics of the object, but also record and reproduce the change of the three-dimensional object with time (T), which is a kind The hologram with extremely high anti-counterfeiting performance has the following characteristics compared with ordinary 2D/3D or true three-dimensional holography: 1 huge amount of information, complicated production process: ordinary holographic anti-counterfeit label can often be completed by several exposures, and four-dimensional production is made. Holograms need to record tens or even hundreds of frames of two-dimensional images, so that the number of exposures is tens or even hundreds of times that of ordinary holography, which requires specialized equipment and more elaborate processes.