There is dust on the laser and it needs to be cleaned.
The material that is cut out with laser engraving is removed from the larger material as dust and very small fragments. The material is disintegrated into dust that goes into the air or on the floor in small quantities.
diamond dust laser other diamond
You can take a normal laser pointer and point it at smoke, dust, fog, steam, etc. and the laser will appear. The normal old laser is now safe to "touch".
toner
The reason we can only see lasers through dust or cloudy water is because our eye can only see light that enters directly into them. When a laser travels across our plane of vision the laser beam is traveling in a straight line, but when it hits the small particles of dust that light is being reflected in an infinite number of directions. A portion of those reflected light rays enter our eyes resulting in what appears to be a laser beam.
Toner is used in laser printers and photocopiers.
You can see light rays with dust, flour, etc. If you turn on a flashlight, you can drop dust right where the light travels to actually see that beam of light. The same thing happens with red laser beams.
usually dust of some kind, occasionally water vapor, reflecting the laser light. I am assuming, of course, the part of the beam outside the excitation tube.
To make a laser beam visible, you can use particles like dust or smoke in the air to scatter the light and create a visible beam. You can also use a fog machine or special laser beam visualization tools to enhance its visibility.
When a diamond is cut with a laser, it forms a precise incision or engraving. The laser is able to cut through the diamond's structure with high accuracy, creating intricate designs or patterns on its surface.
The laser beam is a narrow, coherent beam of light that doesn't scatter much in clean, clear air. So, it's not visible unless there are small particles in the air, like fog, chalk dust, or mist, that scatter the light and make the beam visible.