Lasersaurs have a manual focus: you need to loosen a screw, adjust the height of the lens based on the material you’re cutting, then tighten the screw. I was having some focusing problems where the lens wasn’t perfectly perpendicular with the incoming laser and the bottom of the focusing tube would clip the laser. I’m also not thrilled with guessing at half-the-height of 1/4″ baltic birch vs half-the-height of 1/8″ material, so I made a combination tool for setting the focus height as well as making the tube perpendicular with the bed.
The planar tool is also good for bed alignment/adjustment, the lens should always be the same distance from the bed at any point.