Would it be ok, to have an option for PI to perform an autofocus on each map, just before it starts the map acquisition? Perhaps it should just utilize the center of the map for this optional auto-focus? In other words, (if an auto-focus option is specified), drive to the center of the current automated map, based on a fit to the corner Z positions, perform the auto-focus, then adjust the corner Z positions based on the auto-focus offset, then start the map acquisition using the newly adjusted corner positions. How does that sound?
john
I don't think this would work - because sometimes when the corners are in focus - the center is not in focus - it could be on a spot of epoxy. I'm not sure how important this is - I need to check on acquired data to see the effect on intensity of it being slightly out of focus
Ah, yes, OK.
Intensity loss as a function of stage Z has been documented previously by many investigators- including yours truly. Here's an excerpt from an old study I did many years ago at UC Berkeley:
We should try to minimize the Z focus error to get the most quantitative results. This would be another advantage to synchronized WDS and EDS stage mapping. That is, major elements, which are most sensitive to Bragg defocusing effects (because of their high precision), could be performed using EDS which doesn't have these defocus effects, while trace elements could be done using WDS. Since the precision of trace elements is significantly lower, these defocus effects would be less evident.
One other idea I had is that along with an optional auto-focus checkbox, we could designate a particular stage position as the "auto focus position". Then when the auto-focus is performed, the resulting correction is applied to all 4 corners before the scan is started.
john