What are the air bubbles in the CO2 laser tube and what to do to avoid them?-Bunny

First of all, for those who do not know what these elements are, the air bubbles that form inside the laser tube are small concentrations of air that occur when changing the tube or the water of the chiller, which causes air to enter and form the bubbles. It is not a big problem, but they should remove as soon as possible to ensure good lightning quality, as well as the results.

These small concentrations of air, located in the refrigerator chamber of the laser tube, can cause a reduction in heat transfer. The size of the bubbles directly affects the efficiency of the chamber, the larger the size the less the system will cool. We must take into account the temperature recommended to work with the laser tube, which should not exceed 25 degrees, thus ensuring better performance.

If these air concentrations locate in the optical system of the tube, either the final mirror or the lens, they may overheat, completely misaligned the laser beam.

Possible common causes for air concentrations to occur are:

  1. Air inlet in the cooling system through leaking connectors
  2. Pump cavitation
  3. The air not remove during initial startup

How to prevent them from forming?

  1. Make sure all hoses are airtight to avoid any air ingress.
  2. Use hoses of the same diameter throughout the system
  3. Do not use restrictive connectors or seals to extend the hoses.
  4. The water level in the tank must be correct, to avoid splashing and oxygenate the cooling medium.
  5. Check that the hoses not bent or have narrow radii of curvature.

How to remove bubbles?

  1. To eliminate large air bubbles, you can wait for the bubbles to disperse naturally. Although sometimes this does not work with very large bubbles in the optics cooling system. Or, the laser tube or the machine can tilte to help the bubbles leave the tube.
  2. By rotating the laser tube so that the water outlet is the highest point of the cooling loop. This will prevent air bubbles from forming around the cavity of the reflecting mirror.
  3. Pinching the water cooling tube to create a pressure differential. When released, the bubbles should come out.
  4. It is essential to use the appropriate cooling systems for each tube and machine size.

In short, we must first ensure that the system is a closed loop, there is no air intake. In case of bubbles, the steps indicated above must be followed to eliminate them and, of course, preventive maintenance.