I took a bunch of scans of the PSL with the Beamscan and compared them with some razorblade occlusion measurements
The first steering mirror after the beam exits the PSL was removed, and data was taken at this point in the beam path.
The numbers for the waist derived from my razorblade measurements are on the plot in green. The disagreement seems not horrible to me.
We should still fix the beamscan, and think about buying another (newer) one.
I am told that the beamscan axis drawn on the head (labeled "1" and "2"), not the slit axis is what sets the direction of the field you are sampling. Data for both vertical and horizontal spatial modes of the beam are included. There is some ellipticity to the beam that I will have to account for in choosing my (new?) mode matching solution.
Error bars are included on the green point, they are just small.