Author Topic: Beam Defocuses When Using the PfE Image Aquire  (Read 101 times)

Bill_Mushock

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Beam Defocuses When Using the PfE Image Aquire
« on: October 15, 2019, 01:41:09 pm »
So here is the problem. When we digitize an image for the purpose of doing a line profile analysis, the OL fine focus resets to some default value which in our case is 132. This leaves our beam in a slightly defocused/larger state. You may not notice this if you are taking low mag images (<3-4kx). You will also not notice a change in the JEOL EOS Monitor window until you turn the OL Focus on the console one click which updates the monitor. The real issue for us is that we are now digitizing a line traverse with a slightly larger probe diameter. This behavior has been observed on at least one other 8900.

Can anyone else out there confirm this problem on your 8900. Have you come up with a work around? If your doing line traverses in tight spots, you definitely want to check this out.

Probeman

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Re: Beam Defocuses When Using the PfE Image Aquire
« Reply #1 on: October 15, 2019, 02:25:45 pm »
Hi Bill,
Not having a JEOL instrument, my question would be: on the JEOL 8900 how does the objective lens focus relate to the beam size command?

For example, on our Cameca instrument we set the beam size to zero and then adjust the fine focus to get the sharpest image. Once that is done, that focus is "remembered" as the focus for a zero size beam and fully focused image.

After that you can perform your quant analyses at different beam sizes (e.g., 5 um or 10 um), but when you go to acquire another image (whether for documentation or digitizing points or traverses) in Probe for EPMA, the size gets set to zero automatically which should (if the instrument is stable), give one the best image focus because the instrument remembers what the exact OL value is for a fully focused beam.

So again, if you have the beam size set to 0, and you adjust the focus, does the instrument not remember what the focus is if the beam size is changed?
« Last Edit: October 15, 2019, 02:28:52 pm by Probeman »
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DavidAdams

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Re: Beam Defocuses When Using the PfE Image Aquire
« Reply #2 on: October 16, 2019, 05:41:20 am »
Hi,

In my testing in the JEOL software on my 8900 imaging works similar to your CAMECA instruments. I find a feature of interest, focus using the focusing knob and the objective lens values are remembered. Imaging and all other activities remember the OL values in the JEOL software even changing between beam sizes the OL values don't change unless one actively changes them using the software or the focus knob.

I'm not sure why when PfE sets the beam size to 0 when imaging that there is a change. It might be one of those weird order-of-operation problems that 8900s seem to have when sending it settings. Maybe sending the set to 0 command should be the first thing that is sent?

-dave

Probeman

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Re: Beam Defocuses When Using the PfE Image Aquire
« Reply #3 on: October 16, 2019, 07:40:35 am »
Hi,

In my testing in the JEOL software on my 8900 imaging works similar to your CAMECA instruments. I find a feature of interest, focus using the focusing knob and the objective lens values are remembered. Imaging and all other activities remember the OL values in the JEOL software even changing between beam sizes the OL values don't change unless one actively changes them using the software or the focus knob.

I'm not sure why when PfE sets the beam size to 0 when imaging that there is a change. It might be one of those weird order-of-operation problems that 8900s seem to have when sending it settings. Maybe sending the set to 0 command should be the first thing that is sent?

-dave

Hi Dave,
You're saying there is a change in the objective lens (from what one would consider to be focused), when the beam size is set to zero on the JEOL 8900 (I wonder if this is something also seen on the JEOL 8200/8500?). 

Does this happen even when the beam size is already zero or does it happen only when the default beam size is non-zero?  And what OL value is it changing to and why?

Another question: on the Cameca setting the beam from zero to non-zero changes the objective lens setting by a fixed amount.  When change the beam back to zero size doesn't the OL return to the previous value?

Maybe someone could create a table showing what is going on with the interaction between the beam size and OL? I really don't understand exactly what the relationship is on the 8900.

Another thing to try is to check the "Skip Beam Scan Modes" checkbox in the Imaging window, and then no column conditions are sent, prior to the image acquisition.
« Last Edit: October 16, 2019, 09:29:54 am by Probeman »
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DavidAdams

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Re: Beam Defocuses When Using the PfE Image Aquire
« Reply #4 on: October 16, 2019, 11:36:01 am »
Hi John,

When using the JEOL software there is no change in the objective lens when the beam size is set to zero or any other beam size. The behavior that Bill and I are seeing occurs when using PfE to image. I can only speculate as to what is going on between PfE and the instrument. Based on observations it may be when PfE tells the 8900 to set the beam to zero before beginning the image acquisition.

The behavior I see on my machine is that even when the probe diameter is zero that the OL values change when beginning an image in PfE.

When changing the beam diameter on the 8900 the objective lens values DO NOT change. They remain at the values set when focusing under a beam diameter set to zero.

-dave

Probeman

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Re: Beam Defocuses When Using the PfE Image Aquire
« Reply #5 on: October 16, 2019, 12:10:00 pm »
Hi Dave,
I really appreciate the additional information, but I'm still having difficulty understanding what it going on, so sorry if I sound a little dense.

The thing I'm having trouble with is that the beam size command that is sent, when changing the beam size in the analytical conditions dialog, is *exactly* the same command that is sent from just prior to acquiring an image. In both cases it is the driver J8K_SetSize function.

Can we do a sanity check and check the "Skip Set Beam Scan Modes" checkbox in the Imaging window and see if the OL still changes prior to acquiring an image? I expect the OL might not change and then we can do some further testing to track down the actual culprit

For example, one can temporarily turn off the set beam size function in the probewin.ini file by setting the BeamSizePresent flag equal to zero.  Maybe it's got nothing to do with setting the beam size!

Also it would be helpful to know if there is any consistency in how much and in which direction the OL is changing when acquiring an image...  a little data might be nice.   :)
« Last Edit: October 16, 2019, 12:12:57 pm by Probeman »
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Probeman

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Re: Beam Defocuses When Using the PfE Image Aquire
« Reply #6 on: October 16, 2019, 12:16:02 pm »
When using the JEOL software there is no change in the objective lens when the beam size is set to zero or any other beam size. The behavior that Bill and I are seeing occurs when using PfE to image. I can only speculate as to what is going on between PfE and the instrument. Based on observations it may be when PfE tells the 8900 to set the beam to zero before beginning the image acquisition.

OK, I just saw you say that changing the beam size in the JEOL software does not change the OL value on the 8900!

So if you set the beam size to zero or non-zero in the PFE analytical conditions dialog, does the OL value also not change?
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Bill_Mushock

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Re: Beam Defocuses When Using the PfE Image Aquire
« Reply #7 on: October 16, 2019, 12:17:13 pm »
Dave,

Could you could try this test for me please.

1.With JEOL software set the spot size to 0
2. Set your Ol coarse one click lower or higher and refocus with the OL Fine only. (You should be able to do this for several coarse settings)
3. Select a 5um spot size
4. Set the spot size back to 0
5. Is the image focused? If so this problem is unique to my instrument.

Bill_Mushock

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Re: Beam Defocuses When Using the PfE Image Aquire
« Reply #8 on: October 16, 2019, 12:33:43 pm »
Let me explain the last post. I did some tests on the 8900 this morning and found if I focus with the beam set to 0 on the JEOL software, then change the spot size to something other than 0 and then change back to 0, the OL fine resets to another value. So, its apparent the JEOL software is not storing my settings.

I have no idea when the OL values are set for a 0 spot size. And this week the value for OL fine is 195 vs 135 last week. So obviously I did something to change it.

Probeman

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Re: Beam Defocuses When Using the PfE Image Aquire
« Reply #9 on: October 16, 2019, 12:51:45 pm »
Hi Bill,
Well I'm relieved that you're a little confused because I certainly am!    :)    Why don't you and Dave do some additional testing and get back to us when you've got more information.

As you might have seen above, I suggested some other tests that could also be performed by temporarily turning off some of the functions that are usually called when operating Probe for EPMA. 

There's also two very low level test apps that you can obtain from us if you like: TestType and TestImage. They allow one to test each instrument function call one at a time.  Nice for troubleshooting the instrument. They are in the TestProbe.msi installer. Just let me know by email if you want them.

https://probesoftware.com/smf/index.php?topic=566.msg3207#msg3207

I'm sure we'll get to the bottom of this eventually!
john
« Last Edit: October 16, 2019, 12:53:38 pm by Probeman »
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