Hi ,
As far as I know, a focused laser is used - most likely a YAG laser as a CO2 would just burn the surface.
The image is a 3D point cloud. ( not a true hologram)
The laser scans in X and Y but also dynamically focuses the laser for each point i.e the depth in the z plane.
Because the laser beam is focused, the power density exceeded the damage threshold of the material (acrylic?) only at the "point in space" and no where else in the material along the beam path.
Thats to the best of my limited understanding anyway
![Grin ;D](https://www.machsupport.com/forum/Smileys/default/grin.gif)
ATB
Deker