FAQs

YAG is an acronym for Yttrium Aluminum Garnet, a crystal doped with the rare earth element, Neodymium, abbreviated as Nd:YAG or simply “YAG.” Nd does the lasing, YAG is the host for the Nd. The crystal, called a laser rod, is mostly YAG, only a few percent Nd. A nice characteristic of solid state lasers like YAG is safety. There are no compressed or lethal gasses. Another crystal, vanadate, is used. Loosely speaking, we call it YAG for convenience.

Solid state lasers were the first to be invented (1960), CO2 in 1964 and excimer in 1970. YAG, a solid state laser, has the most experience. Laserod has years of experience in all the major YAG types: lamp, fiber and diode.

Both CO2 and excimers are mixtures of various gases. CO2 is a source of far infrared (IR) radiation only. Excimers are ultraviolet (UV) sources only whereas YAG is multi-wavelength from near IR to UV. YAG is therefore more versatile.

Both carbon dioxide (CO2) and excimer are gas lasers. Solids are denser than gases. YAG is more compact than either of the large and bulky gas lasers. However, Laserod’s principle holds a patent on a compact excimer whose laser head is only a few feet long. And Synrad, a CO2 supplier, offers low power compact CO2 sources. Each laser type has it’s unique applications. For example excimers are used in semiconductor wafer lithography and are famous for eye surgery. But the vast majority of lasers in the world are solid types: computer hard drives and DVDs. But the majority of industrial lasers are CO2.

There are more than 500 laser job shops in the United States. Most specialize in CO2 lasers. Our specialty is YAG. Excimer houses are even more rare. CO2 and YAG are expensive, but excimers tend to be more expensive. The most expensive laser to operate is excimer with UV diode pumped type coming in as a close second. High power industrial excimers are jokingly said to require PhDs for maintenance; UV YAGs require no maintenance, just diode replacement.

The big difference between YAG compared to CO2 lasers is the narrow kerf of less than 0.001 inch (25 microns). Therefore, YAG permits precision machining. Because of the 10:1 wavelength difference, CO2 lasers, as a rule of thumb, have a kerf ten times greater than YAG for the same beam delivery optics. Two examples of optics are fixed beam with moving part and galvanometer (galvo) moving beam. It’s possible to combine a galvo and an X/Y stage or a galvo and a moving web to both move the beam and the part. Both CO2 and YAG lasers integrate well into these devices.

• Wavelength: YAG’s fundamental wavelength is 10 times smaller and produces relatively slag free cuts. YAG can be frequency multiplied (wavelength divided), CO2 cannot. When frequency tripled to the UV, YAG produces a kerf 30 times smaller. Doubled to the green, it’s 20X smaller.
• Peak power: YAG has many orders of magnitude higher peak power (by Q-switching) producing cleaner and smoother cuts due to higher vaporization temperatures. Yet in spite of the higher focused beam temperature, thermal effects are usually negligible. CO2 is not normally Q-switched. Laser peak power is pulse energy divided by how long the laser pulse lasts — femtoseconds to milliseconds.
• Average power: Both are available at multi-kilowatt average powers – which is laser energy delivered per second. By comparison, peak power is energy delivered per pulse.
• Efficiency: CO2 is easily an order of magnitude more efficient than YAG but this is mainly important to scientists, not us machine tool makers.

• Frequency multiplication of YAG from IR to green (1064 to 532nm) and to UV at 355nm allow YAG lasers to compete with excimers.
• Pulse rate of excimer is typically 100 pulses per second (Hz) compared to up to 400,000 for one of our YAGs.
• Pulse energy of excimer can be joules. YAG is millijoules. These orders of magnitude differences in energy and speed make for vastly different applications.
• Applications: low power CO2 is good for thick plastics, high power for thick metal cutting. YAG is good for thin metal cutting and UV YAG for thin plastics. But YAG cuts are cleaner. Q-switched YAG lasers excel in high precision line ablation compared to excimers as area ablators. Consider plated surfaces – a metallized coating of gold, copper, or ITO for example – are easily ablated or patterned by either YAG or excimer. YAG excels as a line scriber, excimer for ablation of small pattern areas. YAG can pattern a thin coating up to 1.6m x 1.6m whereas excimer is an order of magnitude smaller. CO2 lasers cannot ablate copper or gold. Feature size of excimer can be submicron whereas YAG is 10um.