diode 06

The priciple of engraving clear acrylic involves modifying the optical properties of the surface of the material to create largish bubbles. Most diode engraving I have seen creates just superficial surface damage akin to bead blasing ie very fine texture and rather grey, Yes, diode engraving affects the surface transparancy of the acrylic and it is this lack of trasnparancy that creates the apparent engraving effect. Acrylic does not absorb 450 nm light waves to any useful degree so there is insufficient energy transfer to cause heating. Without heat, clear acrylic will not be damaged. The usual way of getting heat into the surface involves adding a film of paint or other substances to act as an energy transfer meduim. The hope is that sufficient heat will conduct into the acrylic to damage it.. The efficiency of this heat transfer is very low, hence disruption to the acrylic surface is minimal and only few microns deep. I have conducted some interesting experiments withi this incedibly low power device and some of the results are remarkable. Even I am surprised and it certainly adds to my laser education .
Wood is an equally diificult material to engrave but it wiill mark if there is sufficient exposure time. This means VERY slow wood engraving. I have some interesting revalations of how the engraving speed can be dramatically improved by decoding the process by which material damagae happens.

[@krisknowlton5935]

"Russ, how are you going to use clear acrylic to show us how diode lasers work when we all know you can't mark on clear acrylic with a blue diode laser?" Russ..."Hold my beer!" As always, I thoroughly enjoyed your video as well as I learned something. I have had some great results engraving on clear glass with a blue diode laser.
Have you ever tried to 'focus' a CO2 beam in the middle of a piece of clear acrylic to see if you get a similar result as you did with the diode laser?

[@SarbarMultimedia]

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[@SarbarMultimedia]

Hi Kris
I have not given up on using acrylic as my "lab assistant". I know it cannot help in the way it did with a CO2 beam but there are other ways I think it can be useful. I say this with knowledge because I am half way through the next video. and..........Your patience will be rewarded. I have not yet tackled clear glass because I have been mesmerised by other unexpected discoveries that have slowed me down. However, the mechanism for damaging glass is different to that of acrylic but will still require some sort of energy transfer mechanism because the energy absoption of glass is little better than acrylc. I'm basically impatient and to engrave glass at 10mm /s (a guess) with a diode laser when I'm used to 400mm/s with the CO2 will drive me crazy. This is why I want to understand what's actually happening with the beam, particularly the focus because energy density (light INTENSITY) at the material suface is all important. I don't think this 5 wat laser is well focused at present to extract it's best performance Thus I have to understand what I have and see if it can be improved.