There are now a couple of video snippets showing the lasering process on the home page.
The laser works by focusing the invisible beam to a very fine point, moving the head (containing the focusing lens) in tiny increments slowly across the material to be "marked". The laser beam vaporizes the surface, usually as tiny puffs of smoke.
When lasering a piece of wood, I often need to put a protective layer over the top (mask) and laser through that mask and mark the surface. The mask keeps the smoke from staining the wood - peel the mask off and the smoke residue goes with it.
When doing cork coasters (a favorite), the smoke residue is not so much that a mask works well. The cork is "marked" and leaves little residue.
The process is not a fast one, as can be seen in the video clips. A large (for my laser) sign of about 9" by 12" can take 45 minutes or more for a single pass. To get very deep penetration in wood, which gives relief to the engraving, two or more passes must be done. For cork coasters, each coaster takes from 3 to 6 minutes. Ganging up to do more at once (using a template to position them exactly) only reduces the "reload" time - each coaster has to have the same amount of time to get the desired result.
There is a delicate balance between speed and power to get a good mark that does not take too long to create.