Quote from: Nick Bulloss on February 08, 2017, 07:01:40 AM
Hi All,
We have been using Digitize Image (for the first time) recently. We collected a nice BSE image at a slow scan rate, digitized points and then ran them. The points analyzed were not the points digitized, each was off by the same increment in Y and (largely) in X. Upon investigation we see a shift in the image position with scan rate, which (per Cameca) cannot be corrected for. I'm curious how people deal with this shift, am I resigned to checking each point after digitizing?
Thanks,
Nick
Hi Nick,
I also see this on my Sx100, but in my calibration efforts which are described in a number of other topics, the hysteresis effects you seem to be describing are essentially zero at the slowest video imaging speeds. If you need exact reproducibility for analyzing small inclusions, then you might want to utilize the "Use Beam Deflection for Position" checkbox along with the Digitize Image feature.
See the following topics for more information:
http://smf.probesoftware.com/index.php?topic=831.0
http://smf.probesoftware.com/index.php?topic=329.msg5319#msg5319
Quote from: Joe Boesenberg on August 29, 2025, 05:44:30 PMOn the topic of setting up and analyzing spots with Digitize Image:
Normally when putting in points without Digitize Image, I jog the stage, then click on Single Point to add the point. How does PfE deal with stage jog if I use Digitize Image to put in points. There is no jog involved. Does PfE use some kind of image correlation with the live image prior to analyzing the point? Sounds like the lack of jog might have been the problem Nick Bulloss was having above.
When one uses the Digitize Image feature in Probe for EPMA from the Automate! window:
https://smf.probesoftware.com/index.php?topic=70.msg13372#msg13372
the points are saved to the current position database as a list of points. When this list of points (position sample(s)) is automatically acquired, the points are acquired exactly the same as points digitized manually using the Single Point, Shotgun or other methods. That is a stage jog is applied for each point as decided by the JEOL stage system.
Note that for best accuracy one should acquire the image utilized for digitizing points using the slowest scan acquisition speed to reduce scan hysteresis as much as possible.
There are several other considerations when calibrating the instrument stage to the scanning system. Perhaps the first thing to ensure is that the beam position in spot mode is the same as the beam position in scanning mode at high magnification. Ideally this adjustment is performed by the instrument engineer, but can be checked by the user on a fluorescent material.
If a temporary adjustment is necessary, the image shift parameters can be utilized. Other considerations:
1. Calibration of the magnification ranges.
Typically EPMA instruments (like SEM instruments) have several ranges of magnification for the scan coils. Ideally one should calibrate the scanning system at both the low and high ends of each magnification range:
https://smf.probesoftware.com/index.php?topic=831.msg5291#msg5291
2. Note that there are two ways to calibrate the scanning system. First a simple two point calibration in Probe for EPMA:
https://smf.probesoftware.com/index.php?topic=138.msg1429#msg1429
and a three point method that also calibrates the scan rotation system at different magnifications using a stage scan image and multiple beam scan images over the same area in CalcImage:
https://smf.probesoftware.com/index.php?topic=396.0
Quote from: Joe Boesenberg on August 29, 2025, 05:44:30 PMAt what magnification does it become reasonable (analytically) to use Beam Deflection with Digitize Image where the probe goes to the image center and not the XYZ of the analysis spot?
It depends on the degree of Bragg defocus on that spectrometer. But my "rule of thumb" is to keep the image size to under 20 to 50 um when using beam deflection acquisition in the Automate! window:
https://smf.probesoftware.com/index.php?topic=70.0
Note that the cool thing about the Beam Deflection acquisition method is that the calibration used to record the stage positions on a image, is the same calibration system used to calculate the beam deflection necessary to return the beam position to that pixel. So it is extremely accurate.