Beam Deflection Acquisition

[Ben Buse]

Hi John,

It seems to work really well. I've tried it at 1 micron and I can do beam deflection without jog called.

Would it be possible to include this in probeimage?

Also I've tried doing a linescan again - not measuring beam current - but it still takes the cup in and out for each point, which for 100 points 1 second each adds a lot of time - anychance of disabling it? - I've just found 'blank beam after move and acquistion' - but unckecing this does not seem to do it

Thanks

Ben

[John Donovan]

It seems to work really well. I've tried it at 1 micron and I can do beam deflection without jog called.

Would it be possible to include this in probeimage?

Hi Ben,
Yes. I will speak to Brian.

Also I've tried doing a linescan again - not measuring beam current - but it still takes the cup in and out for each point, which for 100 points 1 second each adds a lot of time - anychance of disabling it? - I've just found 'blank beam after move and acquistion' - but unckecing this does not seem to do it

OK, so this is a question on PFE?  I will check the behavior.

Note that the beam blank and read faraday are two separate operations.
john

[John Donovan]

Also I've tried doing a linescan again - not measuring beam current - but it still takes the cup in and out for each point, which for 100 points 1 second each adds a lot of time - anychance of disabling it? - I've just found 'blank beam after move and acquistion' - but unckecing this does not seem to do it

Hi Ben,
I found the place where it was inserting the faraday cup when it didn't need to. That is now fixed in the latest version.

Just make sure the "Do not set beam conditions" checkbox is checked.
john

[John Donovan]

Normally when you deflect the beam in the Acquire! | Imaging window, the beam stays deflected until you acquire another image or the Imaging window is closed. 

The reason being that you can utilize the imaging window to select small phases using the acquired image for manual point acquisition in the Acquire! window even if the phase isn't visible in the optical monitor.  Of course you want to be sure you aren't deflecting the beam more than 20 microns or so to avoid Bragg defocusing (unless of course you are only acquiring EDS spectra in Probe for EPMA).  In this mode one can see the beam deflection spot in the Acquire! window acquisition displayed as a small yellow circle.

In addition, the actual stage position of the deflected beam is recorded in the acquisition parameters and can also be displayed in the acquired image (assuming you saved it to the PFE database).

Recently Julien Allaz asked if we could add a button to re-center the beam without closing the Imaging window and rather than add yet another button I added a beam re-center call to the toggle beam/stage button as seen here:



Hopefully this will work for everyone.  Available in PFE 12.2.0.

[John Donovan]

Version 12.2.0 contains optimized code for Beam Deflection acquisition both manually from the Acquire! window and automated from the Automate! window.

Beam deflection acquisition is useful for analyzing small phases that are not easily visible in the light optics display, where precise positioning of the beam spot is essential.  But of course one needs to be careful to not deflect the beam outside the Bragg defocus limit which is usually about 20 - 30 um.

As a reminder, manual beam deflection acquisition is performed using the Acquire! window. Basically one acquires an image in the Imaging window, then using the mouse they click on the image.  The beam is deflected to that pixel.  Note  that one can observe the beam position in the Acquire! window display as seen here:



The stage coordinates of the deflected beam are displayed.  Then one simply acquires manual acquisition points from the Acquire! window for the current beam deflected position, and the beam deflected stage coordinates are recorded.  If you saved the image to your probe run database from the Imaging window, one can also display the beam deflected positions on the saved image just as one does for stage movement acquisition.

For automated beam deflection acquisition (say a very small step size traverse across a small inclusion), one uses the Digitize Image option from the Automate! window. First one creates a new std, unk or wavescan position sample using the Digitize (button) window, then one clicks the Digitize Image button and acquires an image of the appropriate sample area, and using the mouse, one clicks on the image to digitize selected beam spots.

For automated acquisition of these beam deflected positions, one then simply checks the Use Beam Deflection for Position checkbox in the Automate window, and the software will move the stage to the center of the position sample image and then deflect the beam as digitized.   For subsequent position samples, the software will then again move the stage to the center of each position sample, and again deflect the beam based on the image extents of each digitized image position sample.