Hi folks,
I played around a bit more:
Bottom line: I start left with the focus way off (10 mm), laser at 100%, and then close in into focus on the right. As you can see the transistion from “not scorched at all” to “totally black” is happening relatively fast.
Second line: Started left, increasing laster power in 1% steps to reach 100% on the right, and dwell with the laser for 1 millisecond on each pixel. Again, quick transition.
Top line: same, but laser a bit out of focus (2mm out of focus).
I also tried the grayscale square on very white photo inkjet paper, and there its either white or black, no grayscales possible.
What I infer is: There is the assumed exponential effect: First the laser is reflected very much by the unscorched surface - the whiter, the more is reflected. Slowly heat builds up, and the material starts to darken. Darken means better absorption of light, heat builds up quicker, dakrening fastens, heat builds up even quicker, and ere you can say “Fire!” you have reached complete black.
In that sense my greyscale squeres were kindof a lucky shot I’d say!
I’d tend to give up here and say: Too many variables and to fast effects to keep control of it, but I have found a few examples that tell a different story:
- https://www.troteclaser.com/de/know-how/tipps-fuer-laseranwender/graustufenmatrix/
- https://forum.lightburnsoftware.com/t/laser-parameter-grayscale-matrix/409/13
- https://www.prusaprinters.org/de/prints/21958-laser-calibration-power-vs-feedrate-for-marlinrepe
So after all, I suppose my original approach would work if I did not run into the PWM problem. And it’s there - I played around with the grayscale square, and here it’s clear to see:
I gues I’ll contact support and ask for options. It would be sooo cool if we all could use the fast method I used for the square…