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thanks for all the replys. Yes, I see all these problems which is why
I always defocus and never raster. Just checking to make sure I was
standing my ground on firm ground. You know, new users to the lab
saying "we always did it this way before...". Thanks for letting me
check with you, I feel confident that I haven't missed something.
AK: I sometimes use a defocussed beam, but for the reason mentioned by
Andy Buckley I stay away from rastering. The JEOL 8200 has a "beam
diameter" parameter in its EOS setup, which is fairly accurate judging
from materials that show the "burn" spot.......
PH: I just have to add my 2 or maybe 4 cents into this discussion.
Cent 1. Rastering while analyzing is the worst possible way to
do a "bulk" analysis of inhomogeneous materials due to the "flag pole
effect" (my term or I may have heard it a long time ago). The beam is
not rastered evenly. A delay is programmed into the raster at the
beginning of each horizontal line to compensate for hysteresis in the
scanning coils. This produces a "flagpole" of extra dwell time at the
left side of the raster........