CO2-laser, Nd:YAG-laser or a fiberlaser?
At this moment 3 types of laser sources are mostly used for industrial production: the CO2-laser, the Nd:YAG-laser and the fiber laser. The fiber laser is gaining territory from the old Nd:YAG-laser, and also many CO2 lasers are being replaced by fiber lasers.
Does it mean fiber lasers are the best lasers? Not always, because the application is decisive for the choice.
Lasers are light sources with a beam in only one fixed wavelength. For CO2-lasers this wavelength is 10 640nm whilst the Nd:YAG and most fiber lasers have wavelengths of 1064nm. The fiber laser is the ideal successor of the Nd:YAG laser for most of his applications. You could compare the Nd:YAG laser with an old filament light bulb, whereas the fiber laser could be compared to a LED light. The fiber has better reliability, a longer lifetime, is higher energy efficient and has higher overall beam quality. The comparison works quite well, because in fact the fiber laser gets his energy from high power light diodes (LED’s). The old Nd:YAG lasers are pumped with flashbulps, but more modern YAG lasers also get their energy from high power diodes. The biggest difference in structure is that the laser light in fiber lasers is generated inside… ...a glass fiber. The Nd:YAG laser is build together from components that need alignment. The open configuration is also sensitive to dust particles.
CO2-lasers are a different story. With their 10 times longer wavelength it has a completely different absorption coefficient compared to the fiber’s wavelength. Where a fiber laser beam goes directly through glass, the CO2-laser is almost completely absorbed by the very same glass. That is why CO2-lasers are able to engrave glass and fiber lasers are not. On metals most wavelengths have little absorption. Both wavelengths will reflect most of their energy on stainless steel or aluminum. In order to process these kind of materials with these wavelengths we need big laser power. To be precise: we need a high energy density. Fiber laser markers with only 20W of optical energy can be suitable to make fast engravings in metals. This is due to the small spot size and the ability to pulse with high peak powers. With short pulses of 10 kW the molecules of a metal surface can be kicked into gas phase before the needed time for melting is reached. Of course, only in a small area. Actually, in the order magnitude of about 0,001 square mm (about 0.0000015 square inch). That is why the fiber laser can make such a fine detailed engraving. For foil cutting, this is also a good laser. The short pulse gives no time for the foil to deform, which will be the case when a higher laser power are used.
A CO2-laser with such high peak powers is not easy produced. Most of these lasers only pulse to their average power value. That is why a low power CO2-laser is not suited for processing metals. Although there are additives like Thermark that are used with CO2-lasers to print on metals. But there the additive has the absorption. In the field of organic materials such as plastics, paper, wood and stone the CO2-laser has the advantage. It is used for engraving, cutting and welding (plastics).
Engraving plastics with a CO2-laser will mostly result in a deeper engraving with low discoloration. If high contrast is wanted the fiberlaser prevails. In some cases even the much more expensive UV-laser needs to be considered. For each application there probably is a suitable laser. Alas, it is not possible to use one type of laser in all kinds of applications. On the website of Lion Lasers you can see various examples that are made with different types of lasers. Of cource we will be happy to help you find the right laser system for your application. We will always go for the most economic alternative with the best result.