Wuhan GStar Laser Tech. Co., Ltd.

We can see some arts and crafts with a number of carved pictures inside the glass or crystal handicrafts in crystal gifts. These shinny and transparent crystal products have something close to do with the laser subsurface engraving technology. Today, this article will lift the mysterious veil of crystal crafts and introduce some laser subsurface engraving products and technologies.

Principles of laser subsurface engraving

In fact, the crafts we usually see, most of them are not real crystals, but artificial crystals. “Laser” is a most useful tool to engrave 3D pictures in the artificial crystals (also called crystal glass). It uses a laser subsurface engraving technology, engraves a two-dimensional or three-dimensional image inside the crystal (glass). Carving is an ancient art. Ordinary carving is engraved from the outside of the object and form different shapes that we want, but laser can work from the core parts of the object to realize its functions like Monkey King. If you check these glass and crystal crafts carefully, you can not find any opening mouth or ending which is made by the engraver, this point, laser is smarter than Monkey King, for Money King has to find a gap before he goes into the other’s stomach. The principles of laser subsurface engraving are very simple. To be able to engrave on glass, laser energy density must be higher than the critical value of destruction, or threshold value, laser energy density at certain place has something to do with the size of the light spot. With the same bouquet of laser spot, the smaller light spot can form bigger energy density. In this case, through appropriate focus, we can make laser energy density to be lower than the glass destruction value before the laser goes into the glass until the arrival of the laser. In the area which we wish to be processed, we have to make the energy density to be higher than the critical value, laser can bring strong pulse in a short time, and the energy can have the crystals breakdown once the crystal feels the heat from the laser, it also brings some while spots and forms the pre-shapes in the crystals, and the rest part of the glass or crystals are still intact....

Products made by laser subsurface engraving

Laser processing system and computer numerical control technology can constitute a high efficient, automatically processing equipment which has opened up broad prospects for high-quality, efficient and low-cost production process. Laser subsurface engraving machine is new equipment used both laser technology and computer technology

Laser subsurface engraving machine applies high-performance and numerical control technology, though self-studied optical system, control system and computer software, it can precisely en engrave 3D dynamic images inside the 3D crystals and glass, this technology solved the problems that engraving speed is slow, working systems are not stable, lost laser points, the software for dealing with the image and font is not perfect, the control card of the computer interface leads that laser points expose uneven, automatic control devices are not perfect, the cost of equipment is low. This device improves the system’s efficiency, accuracy, maintainability, versatility and security. Color laser subsurface engraver might come true...

Artificial crystal is one kind of glass with high Pb, or called lead crystal. That is, the ordinary glass (SiO2) is added 24% of PbO (plumbic oxide), and then turn to be artificial crystal which light and transparency is similar to the crystal.

Characteristics:

PbO contents ‘international standard is 24% in artificial crystal, when its chemical property is best. Compared with the ordinary glass, artificial crystal is with big SP. GR(specific gravity) and heavy handle; High IOR (index of refraction), can transmit a colorful spectrum; High hardness, and wear-resistant....

There are many characteristics of the laser: First of all, is monochrome, or a single frequency. At the same time, some laser can produce different frequency of laser, but the laser is isolated from each other, be used separately. Second, the laser light is coherent. Coherent light is characterized by its light waves are all synchronized; the whole beam is like a "wave line." Third, the laser is highly concentrated, meaning that it goes a long distance before it is dispersed or converged.

Laser is an invention of a light source in 1960s. LASER English is the acronym of "light amplification by stimulated radiation,” There are many kinds of lasers, to a number of large-size as soccer field, as small as a grain of rice or salt. Gas lasers are; helium - Ne laser and the argon laser; solid-state laser are; ruby lasers, etc;

Semiconductor laser are; diode lasers, like CD drive, DVD and CD-ROM’s. Each has its own way of laser generation.

Laser processing technology is such a technology that using the interaction of the laser beams and the material properties of the material (including metal and non-metallic) for cutting, welding, surface treatment, drilling, micro processing as well as lamp-house to identify objects, The larges traditional application areas is laser processing technology. Laser technology is an integrated technology, which related to optical, mechanical, electrical, materials testing and other subjects. Traditionally, the general scope of its study can be divided into:

1. Laser processing system. Including lasers, optical systems, machine tools, control systems and test systems.

2. Laser processing techniques. Including cutting, welding, surface treatment, drilling, marking, scribing, and other fine-tuning process....

Laser’s first Chinese name is "Lei She", "Lai Se", it is the transliteration of its English name LASER, who is the acronym of the first letter of English words “Light Amplification by Stimulated Emission of Radiation “. It means "stimulated emission of optical amplification”. Laser’s full name in English has fully expressed the main laser manufacturing process. 1964, in accordance with China’’’’s famous scientist Qian Xuesen proposition, "light stimulated emission" was called "laser. " Since the 20th century, following the atomic energy, computers, semiconductors, Laser is another major human invention, known as "the fastest knife", "Best-of-foot", "the brightest light" and "exotic laser". As early as 1916, its principle has been found by the famous physicist Albert Einstein, but until 1958 laser was first time manufactured successfully. Laser’s birth is based on the theory preparation, manufacture practice and the urgent need. It was appear with unusually fast development, the development of laser not only renew the old optical science and optical technology, but also lead to the appearance of the entire new industries there. Laser allows people to effectively use the advanced unprecedented ways and means to get an unprecedented efficiency and results, thus promoting the development of productive forces.

For many years the laser marking is applied in products marking of all kinds of trades with many new marking systems emerging endlessly. It has now taken place of the traditional marking method with its unique characteristics such as: Punching, printing, and chemical eroding characaters, Englsih letters, numbers and graphs on the surface of various machinery parts, elctroinc components, IC module, appratus, clock, motor nameplate, tools and even food packages. It has wide application in these fields.

Laser marking is to use high-energy-density laser beam on the object, making the surface of it to change chemcially or physically, and thus marking visible design on it. The high-energy-density beam is focused on the surface of materials and give the material vapouraous burst and form a notch...As the laser beam moves on the surface of the material regularly, it forms a designated image on the surface of the material. The laser marking has much more obvious merits than tradtional marking process.

(1) the marking speed is fast and the marking is clear and permanent....

3. Scanning marking

Scanning marking system is consisted of computer, laser source and x-y scanning system. It needs to input the marking information into the computer and the computer will follow the designed programm to control the laser and x-y scanning system and thus cause the high-energy laser point transferred after special optic system moving and scanning on the surface of the object to form a mark.

Usually X-Y scanning system includes two kinds of structures: One is machanical scanning, the other is vibrating mirror scanning....

Vibrating mirror scanning makring system is mainly consisted of laser source, xy deflexion mirror, focus lens and computer. It shoots the laser beam on the two reflectors (vibrating mirrors), and use the computer to control the reflecting angle of the reflectors. The two reflectors can scan along X, Y axis respectively, causing the deflexion of laser beam which makes the laser focus point with a certain power density produce the required movement on the surface of marking materials, leaving a permanent mark on the material surface. The focula can be in a round or rectangle shape. The working principle can be seen in figure 4. In vibrating mirror marking system, characters and vegtor graph can be used, . Such a method uses computer graphics software to deal with the graphs and the graph is made with high efficiency, high precision and high audencity. As a result the marking quality and speed are greatly impoved. Meanwhile the vibrating mirror scanning marking can use DOT-matrix marking method which is very suitable for on-line marking. It can adpot one or two scanning vibrating mirror according to different speed of the production line. Compared with the array marking mentioned in previous paragraphs, such a marking can mark more DOT-matrix information and has an advantage of marking Chinese character strings.

Due to its wide application, vector marking and DOT-matrix makring, adjustable marking frame, high reponse speed, high marking speed( hundreds of characters per second), high marking quality, well-closed light path and its high adaptability to the environment, the vibrating mirror scanning marking delegated the future developpment of the laser marking machine, and has a promising application future.

4. Full-closed loop laser flying marking based on machine vision feedback...