Now with so many choices on laser marking systems these, it’s no surprise that many people are confused about which is best for their application.
Many people don’t even know that the word “laser” is actually an acronym – light amplification caused by the emission of stimulated radiation – explaining the process by which a laser beam is created. The basic theory here is simple. The gain medium (material used to generate laser light) is excited with light or electricity to generate photons (laser light). All of this takes place in a closed cavity with a total reflecting mirror at one end and a half reflecting mirror at the other. When the internal reflected light gains enough energy, it escapes through the half mirror. And then these high-energy photons are focused to a small spot (like what you did when you used a magnifying glass to focus the sun’s rays to burn things up at school!). In the case of a vector laser, a pair of reflecting mirrors (X and Y deflection) are used to deflect and direct the beam.
This guide will help you understand the capabilities of the three most common lasers on the market today:

Use electrical energy (DC, AC, or RF) to pump (excite/heat) the carbon dioxide gas (and other gases, most commonly nitrogen and helium) sealed inside the laser, and produce a stream of photons.

Nd.YAG is its English abbreviated name, from (Neodymium-doped Yttrium Aluminum Garnet; Nd: Y3Al5O12) or Chinese called yttrium aluminum garnet crystal, Yttrium aluminum garnet crystals are its active substances, the content of Nd atoms in the bulk crystal is 0.6-1.1%. It is a solid laser, which can excite pulsed laser or continuous laser. The emitted laser is infrared wavelength of 1064nm.

A glass fiber doped with rare earth ions (most commonly ((Yb3+)) is diode-pumped and the generating photons are reflected down the fiber to a deflecting mirror.

The basic difference between Nd:YAG/fiber lasers and CO2 lasers is the wavelength of the beam they produced. The light emitted by the laser lies in the “invisible-infrared” region of the electromagnetic spectrum.
The wavelength of light emitted by YAG and fiber lasers (1.064 µm) is 10 times smaller precisely than the wavelength of carbon dioxide lasers (10.6 µm).
This smaller wavelength also means that if the Nd:YAG/fiber and CO2 lasers are used for the same application (with the same settings), the spot size of the Nd:YAG/fiber is much smaller and therefore the resolution of the marking higher.

These wavelengths determine which laser should be used according to its application, as the materials to be marked will have different absorption capabilities (the ability to absorb different wavelengths of light). If a material can absorb light, then it may be affected.

Most metals have high reflectivity and are therefore best suited for Nd:YAG or fiber lasers. The much shorter wavelength means less reflection of the beam on surfaces, so less energy is lost, and therefore easier metal processing. Metals absorb more light energy, will changes its physical properties.

Organic materials such as wood, acrylic, plastics, fabrics and transparent objects are better suited for CO2 laser because of longer wavelengths and more degrees of freedom. However, Nd:YAG and fiber lasers can also be used to mark some non-metals. But, if the object is transparent (eg glass), the YAG/fiber laser will pass through without marking.

Laser marking machines can use a non-contact thermal processing technology to produce alphanumeric characters, barcodes, serial numbers, logos, illustrations and other graphic images.
Is there an easy way to know which is the best fit?
Ideally, a sample of the material would have to be tested, but CO2 for organics, and YAG and its derivatives (fibers, Nd:YAG, etc.) for non-organic materials are usually taken into account.

• Nd:YAG uses lamps or diode groups (arrays) to excite gain media – these require more power and wear out (replacement is very expensive). They also generate a lot of heat and require more heat dissipation. (some water cooling – most use radiators and thermoelectric cooling systems these days)
• Fiber lasers use many single-emitting diodes, which have lower operating costs and extend the life of the fiber. The mean time to failure is greater than 50,000 hours.
• Fiber lasers are more stable at all power levels.
• The light source with optical fiber is completely sealed all the way to the marking head. This prevents dust and particle contamination and extends the working distance between the control unit and marking head. It also reduces any leakage, thus increasing the efficiency of the laser beam.
• Fiber lasers can “start up” faster.
• Fewer replacement parts for fiber lasers. (e.g. resonant mirrors, crystals, liquids and filters)