CO2 vs. Fiber vs. UV Laser – What’s the difference?

How do fiber laser engravers work?

When a fibre laser meets an object it evaporates the surface material to expose deeper material, essentially “carving” by chemical and physical changes. These changes are caused by the light energy (photons) reacting in the target area.

Fibre lasers possess a high electro-optical conversion efficiency, in layman’s terms this means they convert more of the energy to light (compared to CO2). In reality, this means fibre laser systems require less power to effect a material, resulting in a low power consumption for a fibre laser marking machine.

Operating at the 1,064nm wavelength, they are very well suited to metals, but can also operate on a much wider array of materials. This is why they are the most common choice for traceability marks such as barcodes, QR codes and text. Plus, their use for other graphics on things like personalised items, switches, phones, jewellery, becomes more popular day-by-day.

Types of Fiber Lasers

There are two common types of fibre laser you will find offered from manufacturers, we offer both types to suit the users budget. The main difference between these types of technology is the variety of pulse width and frequency.

Q-Switched

These used to be the most commonly found type of fiber laser source, it is also the cheapest. They are typically not as efficient nor do they possess as wide a range of pulse modulations. In turn, this means they are less flexible than a MOPA laser and are much more prone to deforming different materials.

MOPA

A MOPA laser is much more flexible, they have become far more popular and widely available, but not all MOPA systems are the same. Good MOPA systems will have a wide range of pulse width and frequency adjustments available they can suit more materials and are less prone to creating unwanted deformations once setup correctly. However, as mentioned, MOPA laser sources are quite varied in themselves, with both quality and modulation versatility differing between manufacturers. Unfortunately, there are now many MOPA systems on the market with only one or two Pulse Width’s and PRF0, they will be marketed as suitable for metal, but won’t be particularly good at it as you would realistically want upwards of 5 Pulse Width’s to work effectively (our own OEM systems have 17).

All Lotus Laser Systems’ fiber lasers incorporate the MOPA technology, and each have the ability to create very short duration pulses (and therefore lower pulse energies), reducing the heat imparted to the material. This reduction in the heat affected zone (HAZ) provides advantages when marking metal and plastic such as less burning at the edges, and a more homogeneous, higher contrast marking.

How do CO2 laser cutters & engravers work?

CO2 lasers, as the name implies, utilise a gaseous gain medium which can be excited via a couple of methods, either by direct current (DC) or radio
frequency (RF) power supplies. Lotus Laser Systems focus on the latter when it comes to marking applications for a plethora of reasons. To outline a few, RF CO2 lasers are: smaller in size, have greater power stability, operate at lower voltages and have a superior service life compared to the DC variant.
Performance wise, users will benefit from the faster response time and fine output power adjustment when marking materials, but may be limited by the larger spot that results from the 10600 nm wavelength.

RF CO2 lasers can reach high power output figures but often require liquid cooling to prevent thermal distortion of the laser cavity. Lotus Laser Systems will provide a matching industrial water chiller, so the laser system is ready for operation as soon as it is installed.

FORMATS

Plotter (Plotter Laser)

A plotter system is a motion system that usually contains several stepper or servos, rails and belts. Attached to this are a series of 3 or 4 mirrors that deliver the beam via deflection to a focus carriage that usually contains a single layer plano-convex lens.

Whilst operating, the lens moves over the work area, which is usually large and rectangular in shape, to deliver the focused laser to the work piece.

Sealed (Galvo Laser)

This is a sealed unit, typically containing 2 mirrors that are attached to galvanometers. The beam is focused through a fixed lens known as an F-Theta lens that at the 1µm wavelength. The work area is constraint by the characteristics of the lens and is usually quite small and circular in shape. Technically this is known as a beam deflection laser.

TECHNOLOGIES

DC CO2 Lasers

These are the most common type of lasers found in manufacturer systems as they are relatively inexpensive. Although effective, they are slower than RF systems. Moreover, the laser power output will gradually decline and they have a shorter working lifespan (although manufacturers may quote 10,000 hours, this is only when used at low power settings).

RF CO2 Laser Systems

RF systems may be more expensive, but the benefits often outweigh the cost. We opt for this technology in many of our machines so they can operate at much higher speeds, in fact, our systems are typically more than twice the speed of other manufacturers. Unlike DC, the power output of the laser will remain virtually constant over its lifespan. Moreover the quality of the beam delivery and a life expectancy can be over 20,000 hours (almost 8 years of single shift work), so it’s a “no-brainer” when looking at CO2 laser cutters.