I have a laser beam which is focused to a point at a certain distance. I'm then going to use a galvanometer to scan that beam across a plane. Obviously, as the beam scans across the plane, the distance between the beam source and the plane will vary and so the beam will only be focused on some of the plane (a circle equidistant from the central axis of the galvo). I want to minimize this effect.
Obviously the further away the galvo is from the plane where I want the beam focused, the less significant this effect will be. However, that makes for an awkwardly large machine.
Is there some sort of optics I can use to correct this so that the beam will be correctly focused across the target plane?
Edit I wanted to add this as a comment but I don't think I can put images in the comments. What about this arrangement:
This relies on being able to form a collimated beam from the laser - in practice I think it will have some noticeable beam divergence but I'm not sure how bad it would be. It focuses the beam on the target plane whatever steering is given from the galvo:
Obviously I'll have to correct for the deflection introduced by the lens, and it's a bit of a pain because it increases the mirror deflection required for a given beam deflection. But it's a lot easier than eg a moving laser or a custom-printed lens.