Therefore if our laser beam is 6 mm wide and we use a 6 mm diameter, 6 mm focal length ZeSe meniscus lens (not very common!), the beam could measure 0.1 mm = 100 micron in diameter. (Note that, in the example, we chose ZnSe as our lens material and meniscus as its shape, good for CO2.
I've been looking around everywhere for information on this, but all I can find are people trying to cut metal (steel and stainless).All I'm looking for is something powerful enough engrave patterns onto metal (I understand I'll need to invest in air assist to blow metal out of the cuts), but since everyone is concerned with cutting I have not found what wattage laser might be capable of doing so.Or should I simply keep to the Thermark/ceramark stuff to do that kind of work?Any thoughts or knowlege would be welcome. I've directly marked stainless steel with a 50W CO2. The raster speed was set as slow as possible. The optical beam path was fitted with a non-standard collmination lens to give a slight boost to the spot power. The result fresh out of the laser was a darkened area that looked like a marking agent had been used.
When the darkened area was cleaned with steel wool, the design could still be seen in the surface of the stainless. There was very little depth to the etch (could be barely felt with a fingernail). It's all about the energy density/quality of the focused beam and the wavelength of the laser. Different wavelengths have different absorption characteristics on different materials.You can really only use 'wattage' to distinguish between different powers of the same type of laser.
A 20w fiber laser will have little trouble marking most metals where as a 20w co2 laser has pretty much zero chance.Steel and stainless have a relatively high absorption of the wavelength associated with a co2 laser, which is why you will see them listed as being able to be cut on a lower wattage gas assisted co2.Cermark does a good job of leaving a visible mark, I would stick to just using it unless you want to spend 10k + maintenance costs on a machine that can do it without the product.