Sorry mistyped. I meant score.
So a defocused action is where you intentionally set the focus at the wrong height for the material. If you’re scoring 1/8” Baltic birch, for example, you could set the material thickness to 0.5”. The beam will not be focused on the surface, and so it’ll score a wider line. Think of how a flashlight spot gets larger the further away you’re shining it, same concept.
In extreme cases you can take the crumb tray out, set a thin material on the bottom of the glowforge and set your material thickness to 0.50. You’ll be out of focus by just under 2”, leading to a very wide beam.
For more info search the forum for “defocused” and you can see it in action here:
Pay attention to the Labrador retriever and Glowforge logo examples. You can gloss over the TSP problem details, instead concentrate on the differences in line thickness in the finished products.