Probe Image and Cameca SX100

[AndrewLocock]

Several times in the last 4 months I have had an intermittent problem during stage-scan mapping on our Cameca SX100 using Probe Image.
As may be seen in the attached JPGs, one line has vastly higher intensity than the rest of the map.
Because of auto-scaling, this leads to the rest of the map appearing to be black.

Recently, the problem occurred simultaneously on Spectrometers 1 and 2 (LTAP and PET), under the following conditions:
20 kV, 80 nA, 1500 x 1500 pixels, 0.4 x 0.4 microns/pixel, 20 msec dwell, fully focused beam.
Interestingly, Spectrometers 3, 4 and 5, and the BSE signal were not affected.

Previously, a similar error had occurred on Spectrometers 1, 2, and 3 but not 4 nor the SEI signal.
And a couple of days later, on Spectrometers 1, 3 and 5, but not the SEI signal.

Each day the error has occurred, it is at a different line position, but for the spectrometers affected in that particular session, is in the identical position.
I have ruled out a systemic power spike, as I would expect all of the detectors to be affected.

Does anyone have an explanation, or observations of similar behavior? Or better yet, a solution to this occasional problem?

Thanks,
Andrew

[Probeman]

Several times in the last 4 months I have had an intermittent problem during stage-scan mapping on our Cameca SX100 using Probe Image.

...

Each day the error has occurred, it is at a different line position, but for the spectrometers affected in that particular session, is in the identical position.

Hi Andrew,
Identical image position in Y?  This might be the most interesting clue!

Since the slow scan direction is in Y, if there was some kind of a "glitch" at a specific pixel Y position that at least is consistent with the entire scan line being affected in the X direction.  Interesting that the glitched scan line isn't perfectly uniform?  Does it have image information in it?

Do you see glitch at the same image position in stage scans with different pixel sizes or number of pixels in Y? Do you see the glitch in beam scans? 

Might be worth trying a number of fast x-ray maps to try and see how reproducible it is with these different parameters...
john

[AndrewLocock]

Hi John,

During an individual stage-scan mapping session, some (not all) of the spectrometers show glitches, and these are at the same Y-position.
The glitched lines are not uniform and are not equivalent in intensity between spectrometers.
A comparison (at maximum resolution) of part of the lines from Spectrometer 1 - Na, and Spectrometer 2 - Ca, is attached.

The non-uniform intensities could be interpreted to represent image information.

The glitches are uncommon (maybe 1 in 20 mapping sessions) and have occurred at different Y-positions for each session.

I have not seen them on beam-scan maps (but I very rarely do those).
I have not seen them on our JEOL 8900R, whether using Probe Image or not.

Thanks,
Andrew

[Probeman]

During an individual stage-scan mapping session, some (not all) of the spectrometers show glitches, and these are at the same Y-position.

...

The glitches are uncommon (maybe 1 in 20 mapping sessions) and have occurred at different Y-positions for each session.

Hi Andrew,
Different stage y positions or different image Y positions?   I guess both, right?

This is sounding more and more related to a random glitch when moving the stage in Y.  Years ago I saw problems on my new Sx51 at UCB where one or more electrical connections would fail at certain stage positions due to flexing of the flexible connections.  Edgar had to replace the factory wires with more flexible wires and those held up for 10 years after that.

This might be something like that, but more likely a ground loop issue...  which could affect the spectrometer pre-amps?  I'm just guessing here!
john