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Diode lasers vs. Co2 laser tubes

Posted July 2, 2019

There is a big dispute going on for the last couple of years about what is better – a diode laser or a Co2 laser.

Which machine to choose: a Co2 or a laser diode frame?!

What laser technology is better and why?!

Image credit: Endurance Lasers

Obviously, there are two ways of different technologies. The phrase “laser radiation” is the only thing they have in.

We are not here to explain the Co2 laser technology or diode laser (LED) technology, there is a huge number of articles explaining their basic principles, including Wikipedia.

 Here we’ll try to give a basic overview of the key differences between these technologies and which one is better for 3D printer makers, enthusiasts and small businesses.

Ok, let’s start the ‘fight’!

First of all, we need to say that Co2 lasers have one big advantage – it is raw laser power.

The smallest tube that you can find on the market is at least 25 watt and most Co2 machines have the 40-80 watt output power. Professional and industrial units have up to 150 watts.

The industrial units can reach up to 400 watts.

In fact, that is a huge power suitable for fast laser cutting almost any materials except metals. That is a key advantage of this technology.

If you need a laser for an industrial production, then a Co2 is your choice.

However, this technology has certain limitations of too.

All Co2 lasers work on a certain wavelength of 10,6 uM which is longer than the visible light spectrum. Why does it matter –FAR infrared spectrum does not work for all materials. For example, it cuts glass and transparent plexiglass well, but with this wavelength you cannot engrave metals without special paste like Cermark (which is quite expensive).

Almost all materials except metals have a high absorption coefficient of this wavelength. It means that cutting and engraving are quite easy to do with this technique.

So, what problems does a Co2 laser machine have?!

The key problem of Co2 laser machines – is the size. All of them are very big and bulky. A Co2 tube requires much space. More power => longer the tube => bigger the size.

The size does not really matter when we are dealing with an industrial machine but once we are talking about a garage, a workshop or a small store – that matters. Most small entrepreneurs or hobbyists simply do not have enough space.

Another thing that needs to be taken into account is that the mirror systems for Co2 lasers are quite fragile and does not like to be transported a lot. It means that the laser machine is not very much transportable. A heavy weight of the machine makes it hard to import and export, and the shipping costs are extremely high.

Diode lasers features:

  • Portable and low weight (hundred grams with a heatsink).
  • Can be installed on any frame (compatible with GRBL, Reprap, Arduino, etc.).
  • Less powerful (no single diode can do more than 10-watt optical power).
  • Can be easily shipped almost anywhere without the risk of being damaged.
  • Does not require a complicated power system (requires stabilized current and voltage).
  • Have a wide spectrum of wavelength 405-1080 nm.
  • Can be relatively easy fiber coupled.
  • Have a long lifespan (if the diode is not working nothing really happens to it).

Co2 tubes features:

  • More powerful (can reach 400 watts).
  • Very fragile (glass tubes can be damaged easily).
  • A complicated mirror system to aim the beam required (to aim the laser beam you need to use special mirrors to transport the laser beam).
  • Can degrade within a few months (low quality tubes have high diffusion rate what makes them useless within 6-12 month).
  • Very hard to be fiber coupled (a special PIR fiber required to get laser radiation into the fiber).
  • Have a limited wavelength of 10.6 uM (10600 nm) (does not suit for metal etching without special paste).
  • Non-visible radiation (far infrared) from the Co2 laser makes it more risky to operate in the open system.

In general it is quite obvious that if you are limited with your working space and do not need to cut something 24/7 and do not need to cut very thick materials (10 mm or more of plywood or wood), then a diode laser is the best option.

A lot of people and customers prefer diode lasers over Co2 machines because of their smaller size. Unlike the diode laser, you cannot install a Co2 tube on a CNC machine or 3D printer without a very complicated mirror system.  And without a perfect enclosure it might be extremely dangerous to work with.

Some words about laser machines.

We generally spoke more about laser diodes and Co2 tubes, however, I want to direct your attention to laser machines as well.

Diode laser machines have a lower weight and are easy to be shipped and transported. They do not require a lot of power. The portability means that you can take a frame like CNCC or Eleksmaker and put it on the surface to be engraved, for example: a skateboard, sailboard or a wooden table. Some nice examples can be found here.

You can easily keep them in your garage, workshop, or even your basement. Laser diode machines do not make a lot of noise when working and if you do not cut hazard materials no fume extractor is needed.

A pretty good frame for a laser diode unit costs around 100-200$ (without the laser)

Avoid low quality diode lasers:

However, a pretty good Co2 machine would start from 2-3K USD. The use of a cheaper one might cause more headache than joy.

Hold your fire!

All these opportunities make diode lasers the better option for makers, hobbyists and enthusiasts. However, if you need an industrial solution and plan to do a lot of commercial laser cutting and engraving then you need a high-quality Co2 laser machine, like Trotec for example.

We believe that 8 watt / 8.5 watt / 10 watt / 10 watt+ lasers can be a pretty good option to upgrade a 3D printer or a CNC machine.

Keep in mind that most lasers for cutting and engraving are class 4 lasers.

Article written by George I Fomichev, CEO and founder of Endurance Lasers

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