This koi scene and the grayscale test square below are my first attempt at 3D laser engraving. Both are 0.5" thick pieces of walnut. This circle is 3.5" in diameter. The max depth of the burn is 0.15". I burned it with LightBurn on a 100 W CO2 laser in a single ~40 min pass.
Speed: 150 mm/s
Max Power: 100%
Min Power: 19%
Line Interval: 0.03 mm (847 DPI)
Image Mode: Grayscale
Number of Passes: 1
Gamma: 0.5 (In Shape Properties)
Here is the depth map source image:
This is what it looked like straight off of the laser. It was completely covered in char and very messy.
I cleaned the char off by aggressively scrubbing it with a toothbrush using dish soap and water. I finished the piece with two coats of water-based polyurethane spray (Varathane satin).
Here is another finished shot with harsher shadows that accentuate the depth:
I made this test pattern which has all 256 shades of gray to test out the burning response:
Here is what it looks like burned in walnut:
I used the same parameters as those listed above except for the min power which was 12% instead of 19%. 12% corresponds to the point at which this laser begins to fire. I switched to 19% for the final koi burn as the test pattern showed no burning for the first 1.5 rows.