In general, industrial engraving and cutting lasers are divided into two categories based on the application type: metal lasers and non-metal lasers. Scientifically, this classification is due to the different amount of light absorption with different wavelengths in materials. Metals usually reflect a laser beam with a wavelength greater than 2 micrometers and have no absorption at these wavelengths. Therefore, suitable lasers for metals have wavelengths in the range of 1 micrometer or less.

Depending on the gain material, industrial lasers are divided into four general categories: gas lasers, chemical liquid lasers, solid state lasers, and fiber lasers. Dye lasers were the old generation of lasers, which are now almost obsolete due to the difficulty of combining the desired concentration of chemicals and stabilizing it on the surface for a long time.

The most widely used gas laser in the industry is the CO2 laser. This laser works at the wavelength of 10.6 micrometers, at which metals are completely reflective and have no absorption. In addition, the absorption of non-metals at this wavelength is high and this wavelength does not harm the eye at low powers. Therefore, most of the laser engraving and cutting tasks for non-metals is done by CO2 laser that are often working in continuous mode. The cause of this kind of laser is an electrical discharge with a voltage of several thousand volts into the carbon dioxide gas inside a glass chamber. CO2 lasers can cut and engrave non-metals such as wood, MDF, leather, Plexiglas, tombstones, musical instruments, fireplaces, bags, shoes, cabinets, etc. Also, CO2 lasers can cut metal alloys such as non-stick steel and metal composites, and are sometimes used as a gas igniter in certain gaseous metal cuttings.

 

Other categories of industrial lasers have a solid gain material. The two most famous lasers in this category are Neodymium Yag (Nd: YAG) and Neodymium Vanadate (Nd: YVO4). In these lasers, Yag and Vanadate are actually glass crystals that have good heat resistance at high powers. The main action of electron displacement occurs at the laser levels of neodymium. In the past, the energy was applied to the gain material of these lasers by special flash lamps that were similar to the camera flash lamps. But, they wasted a lot of energy and the quality of the output beam was not very good for cutting. Nowadays, the energy of the gain material for solid-state lasers is provided by diode lasers (LDs), which are similar to LEDs. This new method of supplying energy for the gain material is known as diode pumping. So far, this technology has been more common in Europe and the United States. Recently, a company in Isfahan has produced engraving and cutting Yag lasers with diode pumping. The beam of this laser is so sharp that it can cut or engrave metals and non-metals with the least number of passes and the least pleat and the least work deficient.

 

Vanadite solid state lasers, which are the latest technology in the United States, have four advantages over Yag lasers:

1.     Their pulse duration is more than 10 times shorter than Yag lasers. This causes the material to be cut before heating, deformaing and pleating. In addition, the impulse of the light pulse is 10 times stronger.

2.     The diameter of their spot is about 10 times smaller than Yag lasers. This makes them to cut much sharper and more accurate than yag lasers.

3. The output beam quality of these lasers is many times better than Yag lasers, which makes the cut to be sharper and greatly reduces the pleat and work deficient.

4. These types of lasers can also be cooled by air without the need for chillers and cooling liquids.

 

 

The fourth category of industrial lasers includes fiber laser devices in which the generation of laser is done through the optical fiber. Fiber lasers are capable of cutting and engraving metals and non-metals such as silver, gold, aluminum, steel, brass, titanium, platinum, MDF and plastic. Nowadays, they are more commonly used for metals. These types of lasers have lower cutting and engraving quality than solid state lasers with diode pumping. Also, in the case of failure, these devices can’t be repaired and upgraded in Iran and must be replaced. The fiber lasers available in Iran are all Chinese and due to the their very low price, it is not worth manufacturing them in Iran.