JEOL software has this great X-ray mapping option called "Free shape maps" that allows you to acquire X-ray stage maps with more complicated geometries. This is super useful when using long pixel dwell times or if you want to avoid mapping of epoxy in grain mounts (or so I thought).
Recently, I acquired some high current (800nA, focused beam, diabolical laughter), long dwell time stage maps of olivine grains in basaltic glass and the resulting beam damage shows nicely how this mapping option is implemented. Maybe someone else finds this as interesting.
So it looks like that each map line starts 50 microns above the set map limit and runs at faster (maximum?) stage speed and then slows to the set dwell time and acquires the X-ray intensities. This means that there is always a 50 micron wide beam irradiation zone outside of your mapped area in this mapping mode.
Close-ups of the beam damage in the transition zone because it looks interesting.
To post in-line images, login and click on the Gallery link at the top