…The laser spot size directly determines the resolution… Luban also doesn’t work in DPI to my knowledge, and instead works in line interval. Theoretically your line interval should match your dot width (along Y, X is fixed with dot width correction). You can then convert this into a DPI if you so choose, it’s just how many dots fit in an inch.
Example; the 20W has a laser spot of 0.08x0.1. Along Y should theoretically be the 0.1, but it’s close enough to assume anyway either way. You set your interval in Luban to 0.1, which means you get 10 dots per mm, multiply by 25.4, so you get a resolution of 254DPI.
Something like the 10W with it’s 0.05 x 0.2 spot, you’d have to adjust your dot width correction to the width (0.05) and your interval at your laser spot height (0.2) so the software can compensate for the oblong shaped laser to make an actual dot. The larger of the numbers dictate your resolution.
EDIT: I don’t think Luban has dot width correction, however.
EDIT2: Oh it does, that must be recent.