The paint is infused into the glaze. Have to dog out mu USB microscope to take closeups and post them here.

I wanted to thank tweakie for the help he gave me setting up my laser module. My controller is a chinese mach3 usb MK4-V. Gating pwm and output 1 (dir+/-) was not easy for me as I had no idea. The setup in the attachment worked for me. All the credit to Tweakie.cnc

Thank you for the praise 

Excellent solution, I am pleased that you have your laser working.

Tweakie.

The glass CO2 laser tubes have a finite lifetime after which they need to be replaced. Over the years this thread has been running I have fitted 4 or 5 replacement tubes and the latest one has just started to loose power output. Whilst waiting for a new tube to be delivered I decided to try a 5.5 watt diode laser to see if it would laser engrave this little aluminium panel. Although it operates at the blue end of the spectrum I was surprised to discover just how well it performed. Producing this panel was a two stage job using Mach4 to profile cut the aluminium blank (with a rotary cutter) and a laser to do the actual engraving. With a ‘stepover’ of 0.08mm the vector generated toolpath for the engraving had a process time of just over 4 hours which is really not so good. In comparison the raster engraving process time was just 27 minutes. This time saving relates to the number of times an axis has to change direction and of course stop. Although each deceleration / stop / acceleration time may be minute they all accumulate and with a vector toolpath there are many, many thousands of direction changes. Certainly for me, when it comes to lasers, raster engraving is the way forward.
Unfortunately Mach4 does not yet support raster engraving, perhaps one day it will but in the meantime, sadly, alternative machine control software had to be used.

Tweakie.

As this thread still gets a lot of views I thought I would post a little update on the CO2 laser project after some 15 years down the line. I am now on my 5th laser tube and although I have not kept a record of the total hours, each had a (perhaps optimistic) life expectancy of 10,000 hours. Replacing the RECI tubes (which cost around £200 to £300 each) together with alignment, flushing and replacing coolant takes about half a day and could perhaps be considered quite a costly process. All my mirrors and lenses were sourced from II-VI (Coherent) and although initially expensive none have had to be replaced over the years so buying quality sure beats buying cheap optics.
Everything had been running exactly as expected until last week when the coolant circulating pump failed. Well, it did not exactly fail it just started drawing excess current from the 12V supply. An exact replacement was readily available from an online supplier, having UK stock, which was quickly fitted and the CO2 laser was back up and running as usual. The original coolant circulating pump, of Chinese origin, certainly performed sterling service for a great many hours over the years so +1 for its design and quality of manufacture.

Technology marches on and in 2023, for experimental purposes, I purchased a couple of UV laser multi-diode heads (of Chinese origin) at less than £100 each. These heads contain 4 x 5W diodes with precise optics to align each of the 0.08mm x 0.02mm focussed beams, stacked one above the other, to produce a focussed squarcle <0.08mm x 0.08mm. The heads are extremely easy to fit to any existing CNC machine and are way cheap enough to be considered consumables. Unfortunately their operational wavelength is unsuitable for cutting clear acrylic but, so far, I have found that they are ideal for working with wood and anodized aluminium for which I have a current requirement.
Just for fun I have been experimenting with raster engraving 3D optical illusions and although not yet perfect I am improving my technique and thought you may like to see an early example.

Tweakie.

Nice!

Art