How to adjust the mirror velocity for changes in galvo head height?

I have a couple of different lenses. One is quite a distance from the ‘object’ the other lens is much less than half the distance. The machine has no way of knowing how far the lens is from the object, so how could it possibly know how fast it’s scanning the material …?

I see no way to adjust the speed of the beam (mirror velocity) to correct for galvo head height and lens …

Anyone ?


Many many years ago the laser printers we designed used a lens (F-theta) to correct for the flat field error.

My guess is that this method is $$$$ prohibitive.