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A Brief Introduction to Co2 Laser Tube

Co2 Laser Tube

Yufan Sun |

Laser system is rapidly becoming an important part of modern production facilities. Compared with other laser sources, glass CO2 laser tubes are relatively cheap. For this reason, they are now popular tools for small and large projects. There are many kinds of lasers, which can be defined from different angles. Different from the excitation medium, it can be divided into solid-state laser and gas laser. They use different solids or gases as media. At present, the main laser in the field of laser cutting is CO2 laser tube. CO2 laser tube is widely used to cut various materials because it is easier to obtain ideal laser mode and higher energy, stable performance and short shutdown time.

CO2 laser tube structure and working principle

Co2 Laser Tube

The basic structure of a typical sealed off CO2 laser tube is shown in the figure above, which is mainly composed of hard glass, resonator and electrode.           

1. Hard glass        

This part is composed of discharge tube, water cooling tube, gas storage tube and gas return tube made of GG17 material. The discharge tube is the key component in CO2 laser. It basically determines the characteristics of laser output. The length of discharge tube is directly proportional to the output power. The function of water cooling tube is to cool the working gas, maintain the stability of output power, and prevent the discharge tube from cracking due to heating during discharge pumping. On the one hand, the role of the gas storage tube increases the gas storage capacity of the gain medium, reduces the changes of working gas composition and pressure during discharge, and prolongs the operation life. On the other hand, it enhances the mechanical strength and stability of the discharge tube. The air return tube is a thin spiral tube connecting the two electrode spaces in the discharge tube, which can improve the unbalanced distribution of voltage between electrodes caused by electrophoresis. The longer air return tube also avoids the discharge between the air storage tank and the electrode, ensuring that the discharge only occurs in the discharge tube.     

2. Resonator cavity           

This part consists of a full mirror and an output mirror. The full mirror of the resonator is generally based on optical glass, with gold film on the surface. The reflectivity of the gold film mirror near 10.6um is more than 98%; The output mirror of the resonator is generally made of germanium (GE), an infrared material that can transmit 10.6um radiation, on which a multilayer dielectric film is crossed.        

3. Electrode part         

CO2 laser generally adopts cold cathode, which is cylindrical in shape. The selection of cathode material has a great impact on the service life of the laser; The basic requirements for cathode materials are low sputtering rate and low gas absorption.

Excitation process             

In the CO2 laser tube, the main working substance is composed of CO2, nitrogen and helium. CO2 is the gas generating laser radiation, and nitrogen and helium are auxiliary gases. With helium, the thermal relaxation process of 010 level can be accelerated, which is more conducive to the evacuation of laser levels 100 and 020. The addition of nitrogen mainly plays an energy transfer role in CO2 laser tube, which plays a strong role in the accumulation of upper level particles of CO2 laser and high-power and high-efficiency laser output. Excitation condition of CO2 laser tube: in the discharge tube, a direct current of tens of mA or hundreds of mA is usually input. When discharging, the nitrogen molecules in the mixed gas in the discharge tube are excited by the impact of electrons. At this time, the excited nitrogen molecules collide with CO2 molecules. N2 molecules transfer their energy to CO2 molecules. CO2 molecules transition from low energy level to high energy level to form particle number inversion and emit laser.

Advantages of CO2 glass laser tube            

CO2 laser has many advantages, the biggest of which is its original laser power. The smallest tube on the market is at least 25 watts, while the main output power of other tubes on the market is 40-80 watts . Monport provides 60W to 80W borosilicate and sealed glass tubes. You can choose one according to your specific engraving needs.            

Here are some benefits of using CO2 glass laser tubes.         

  1. Lower price: Glass production is cheaper than metal production. This is one of the reasons why these laser tubes are easy to buy at a low price.          
  1. Cutting ability: CO2 laser glass tube generates continuous and stable light beam through direct current to realize consistent cutting on various materials.         
  1. Efficient cooling system: Another advantage of these tubes is their easy cooling mechanism. Therefore, these laser tubes are effective for long-term commercial production. Due to this efficient water cooling system, users can operate laser glass tubes at temperatures up to 70-75 degrees.         
  1. Sufficient service lifeCO2 glass tube laser has sufficient service time. Please note the standard limits specified by the manufacturer. Consumers can choose specific hours according to their energy and production needs.           
  1. Easy maintenance: Unlike RF or other sophisticated laser tubes, CO2 laser glass tubes are easy to maintain. There is no complicated cleaning process, so you don't need professional assistance for maintenance.

What You Need To Know Before Buying

Compared with other laser sources, the glass CO2 laser tubes used in these machines are relatively cheap and are usually classified as consumables with a warranty period ranging from 3 months to 12 months. These simple tips will help you prolong the service life of the tube and get more value for your hard-earned money.

Adaptability to the machine            

If you want to buy a new laser machine, you must first find out what kind of laser tube is fitted, because the quality of laser tubes of different brands varies greatly. There are unscrupulous sellers who repackage defective tubes and sell them as new tubes. EFR laser and RECI laser are internationally recognized high-quality brands. Getting a good tube from the beginning will increase your chances of longevity.

The correct power rating              

Some suppliers sell tubes with their "maximum power" rather than the correct "rated power", which means that you think you are buying 50 watts of tubes, but the actual rated power is 40 watts. A quick and easy guide is the physical size of the tube. For example, if you are buying a 50 Watt tube that is only 800 mm long, you may get a tube rated at 40 watts. This means that your tube may lack power in the application, and you may need to "overdrive" the tube to obtain the required performance.

For example, below typical dimensions for your reference: 


Reliable brand of laser tube

If you are looking for a replacement tube, make sure you buy a reliable brand from a trusted supplier. If the tube you replace fails and your supplier doesn't reply to your email, you may have to buy another new tube. Check the supplier's website and ask for advice.

Manufacturing date   

You can determine the production date according to the label of the tube, which should be close to the date you purchased the product. However, you can expect it to be up to two months old. This date is important because the manufacturer's warranty usually starts from this date, not from the delivery date. 

Don't overdrive the tube!            

Check the manufacturer's data and recommendations to obtain the optimum current for a long life. When you’re using, the carbon dioxide in the tube is decomposed into oxygen and carbon monoxide. When you overdrive the tube, it speeds up the process and shortens the working life. Over time, the performance of the tube degrades and the power output decreases, causing the user to reduce the cutting speed or increase the power. Naturally, this causes the tube to run longer, stiffer or overdrive than usual.


Cleanliness is very important for tube life. Your laser tube loses around 9 to 13% of its laser capacity through its lens and mirrors. When they become dirty, this may increase significantly, and the additional power loss on the working surface will mean that you need to reduce the working speed or increase the laser power. Either way, the laser will work harder or longer than required, thus shortening the life of the tube.

Therefore, it is very important to keep the lens and mirrors of the tube clean. Users should clean and check the tube’s mirror every week, but remember to clean the lens every day.

Watch out for overheating

Never operate a glass CO2 laser tube without sufficient cooling. Overheating reduces performance and may cause permanent damage. Whenever possible, use a dedicated water cooler/cooling unit that has an electrical interface to the laser that stops the laser when the water cooling unit is not running. Sealed water tanks with pumps should only be considered for the smallest laser tube.

Overheating can degrade performance and cause permanent damage. Therefore, use a dedicated chiller or water cooler with an electrical interface, which can automatically stop the laser when the water cooling device is not working. Our Monport industrial chillers use internal sensors to constantly monitor water flow and temperature, so you can work safely and know that your laser tube will not suffer thermal damage. Come to the official website of Monport and choose a water chiller suitable for your CO2 laser engraving machine to realize safe operation!


If you are looking for glass CO2 laser tubes, water chillers, accessories or parts, find the most cost-effective products at Monport. We have shown a variety of laser engravers, so you can find the equipment of your dreams at an affordable price!

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