Menu

GXSM SCAN PARAMETERS

Ben Ouma
2015-03-23
2015-06-29
1 2 > >> (Page 1 of 2)
  • Ben Ouma

    Ben Ouma - 2015-03-23

    Hi guys,
    Could someone kindly tell me the difference between RANGE XY and SCAN XY in the gxsm main window?. What role does the SCAN XY play in the gxsm. Please see the attachment. Thank you.

     

    Last edit: Ben Ouma 2015-03-23
  • Camiel van Hoorn

    Hi Ben,

    The RANGE XY field has to be used for setting the dimensions of the initial image. To zoom in on a particular part of the image for example, the relative coordinates can be entered in the SCAN XY field.
    So normally you can ignore the SCAN XY field.

    Best, Camiel

     
  • Percy Zahl

    Percy Zahl - 2015-03-23

    Sorry, I have to clarify this.

    RANGE is the scan size, OK.

    Scan XY is used to manually set the tip position withing the current/last scan area within the scan coordinate system (rotated eventually).

    • It does NOT matter at all for definition of a scan and while scanning.

    • It's main purpose is to have exact control over the tip position for any probing, manually or script controlled for example.

    • The main difference to the use of "Offset" (possible) is a) the scan coordinate transformation and b) the exact match to the scan as if external/analog offset adding is used there may be minor deviations due to gain and other imprecision out of software control.

    • You will see the tip marker (in the PanView) move to the specified position also!

    To zoom/select a sub area you have multiple options:

    • just adjust the scan range (size) manually, this will zoom on center

    • may adjust offset to position of interest

    • you can use a rectangle, RMB, then "edit" -> "copy+zoom in",
      then press scan start. (It will show a zoomed copy of the old data, just ignore) This calculates new range/offset for you.

    • also you can used rectangle, MMB, -> Get Coordinates, then scan (you may manually adjust the #points, etc to more even numbers you like...

    Note: do not "reactivate" a scan before scan start after calculation new coordinates. As this will put back the last scan's coordinates -- unless you want return to those!

     

    Last edit: Percy Zahl 2015-03-23
  • Ben Ouma

    Ben Ouma - 2015-03-24

    I understand the difference now. Thank you so much for the information Camiel and Percy Zahl. Its clear to me.

    Regards,
    Ben

     
  • Ben Ouma

    Ben Ouma - 2015-03-24

    Dear All,
    When running the TUNE APP in order to initiate a default sweep, what does the VOLUME SINE signify? See the attached file. Thank you.

    Regards,
    Ben

     
  • Percy Zahl

    Percy Zahl - 2015-03-29

    It's the "Volume" or in other words the amplitude of the excitation sine signal.

     
    • Ben Ouma

      Ben Ouma - 2015-04-01

      Thank you so much for the response Percy Zahl.
      We are trying to come up with a home made AFM, and not sure of how to ascertain the gap between the tip and the sample when giving a manual feed in the Z-axis. What indicators can one use to detect the interaction between the tuning fork with tip attached and the surface while manually narrowing the gap between the sample and the tip attached.
      Please help

       

      Last edit: Ben Ouma 2015-04-01
  • Percy Zahl

    Percy Zahl - 2015-04-01

    You should monitor the oscillation, amplitude, damping and freq. shift.

    Usually:
    a) manual coarse approach with visual/optical control until as close as possible safely via visual gap inspection, often via camera.

    b) then you go into automatic approach mode, what in case of GXSM does a repeated cycle of feedback "ON" (assuming you have all feedback parameters tuned and set reasonable -- what may be a guess for the very first time, but you better do simulated "safe tests" in any ways you may come up with...) and coarse approach steps (slider motor, ramp, etc.).

    1) Feedback ON: This will move Z all the way forward unless it reaches "active feedback conditions", i.e. the set point is satisfied. (then done -> normal operation)

    2) If not, it will retract "Z" and engage (what ever is configured) a given number of coarse motion (*) steps, and repeats (1).

    (*) I do not know your system and what coarse mechanism you have to drive.
    The "Mover/Slider" dialog gives you a range of options.

     

    Last edit: Percy Zahl 2015-04-01
  • Ben Ouma

    Ben Ouma - 2015-04-15

    Thanks so much Percy for your help till now. At least have made progress in our work and we still have a bunch of concerns about the gxsm software as highlighted below;

    1. Is there a way we can change VRange Z value (currently set at 500nm) on the gxsm main window? The main window only accept the input of -500nm and 500nm only. This gives us a maximum height of 1um, Can we set larger ranges, say 3um?

    2. The Maximum Scan Speed is currently set at 1um/s this is a pretty slow speed for AFM, are we in a position to alter this speed in the GXSM MK3-A810 DSP Control Window?

    3. We have also noted that when our scans are interrupted/aborted, there is a delay/slow response before aborting. Is this normal occurrence?

    Kindly assist. Thank you.

     
  • Thorsten Wagner

    Thorsten Wagner - 2015-04-15

    You can configure most of the numeric widget by right clicking on them and then choosing the last menu item of the context menu.

    Thorsten :-)

     
    • Yong Lee

      Yong Lee - 2015-04-15

      Hello Thorsten,

      The problem we have is that VRange Z would cannot be changed from 500nm. For example, if I type in 100 and press enter, the value returns back to 500 nm. Is there something wrong with our installation?

      Also, is the apparent delay or slow response of GXSM after the scan stop button is pressed normal?

      Regards,
      Yong

       
  • Ben Ouma

    Ben Ouma - 2015-04-23

    Hi All,
    Now our PLL seems to be responding well, but while scanning for example the features of a standard sample we don't seem to get a good result but just a kinda a funny what would be the problem with our set up? See the attached.
    We confirmed that our tip is sharp. Could something be wrong with our settings or data acquisition?

    Regards,
    Ben

     
  • Percy Zahl

    Percy Zahl - 2015-04-23

    Ben,

    I am really having a hard time to get you some hints, as I nor know your instrument or anything else in the "loop" beyond gxsm and the A810.

    What is the sample at all? Some thing looks "soft".

    But what I would inspect and monitor to find out more:

    How does scan speed effect the imaging/profile contours?

    How do the "error" signals (dF signal) looks looks, did you captured it as well?

    How are the feedback settings, step response,....

    -P

     
  • Ben Ouma

    Ben Ouma - 2015-04-24

    Hi Percy,
    Thanks for your response.

    Our loop is composed of SIGNAL RANGER MK3 PRO-A810, QTF, IV-Converter, LV PZT Amplifiers and the XYZ stage, as attached.

    We actually used a standard sample from Digital Systems company (Pitch of 10um and depth of 200nm.

    The image of the error signal, PLL Excitation Frequency LP, together with the TOPO image in one of the scans is also attached.

    The feedback settings are also as attached, DSP-PAC and DSP Control.

    As of the effects of scan speed on the image, let me monitor carefully and will respond soon.

    Thanks for you help.

    Kind Regards,
    Ben

     
  • Percy Zahl

    Percy Zahl - 2015-04-24

    I mean the instrument. What is it?

    Is it in air, UHV, low-temp, ... I noticed your scan is huge.

    I may be wrong, but in general the tuning fork/qPlus is non ideal in air or even in UHV if NOT cold. Only at low temp you can get it to full potential.

    AND

    I am concerned about huge scans like this for several reasons.

    A TF or qPlus is in general very sensitive with it's high Q. SO you want very very small amplitudes -- look for publications, there are several. And that implies also very very small features -- aka molecules and a like!

    If you drive it "big" and try to run over huge obstacles I am afraid that's not going to work well with this kind of detection.

    But I may be wrong here, at least I've never see it been used for such a huge topo scenario -- please do some more research.

    Try to find better amplitude/df settings -- may help a little.

     
  • Ben Ouma

    Ben Ouma - 2015-04-26

    Hi Percy,
    Thank you let me do more research based on the mentioned concerns will get back. Thanks for the support.

    Regards,
    Ben

     
  • Ben Ouma

    Ben Ouma - 2015-04-27

    Hi,
    Now I got a couple of concerns about the scanning:

    1. Can we disable the y-axis scan (slow scan direction) of the GXSM software?

    2. As currently set, we can only scan a square shape scan range (RANGE XY), can we shrink the y-axis so that we have like a rectangular scan RANGE XY?

    3. Can the software allows for the plotting of trace and retrace on the same window and not use two separate windows for the trace and retrace?

    Kindly assist.

    Best Regards,
    Ben

     
  • Percy Zahl

    Percy Zahl - 2015-04-27

    Just override the Y settings after entering X. It's only the default for convenience to copy X over to Y. Edit X, then edit Y. You can also have independent resolution for X/Y -- just readjust dy or dx, or points, ... Remember to select which of the three Range/Step/Points should be computed from your input via the radio selector on right.

    To disable Y-scan -- you can set the dy to the smallest step it allows (almost disabled), or well, just unplug Y.... or use the Signal Configurator/PatchRack to set Y-scan to the NULL-Signal. Dy=0 is not allowed -- even in general would be possible.

    To plot, yes you can select always a so called "Red" and a "Blue"-Profile via Scan-Popup Menu View->Redline, and then "add Blue Profile" -- the "Blue" goes into the same profile view, but the data is ALWAYS from the consecutive next scan channel N+1. So if you have Topo-X+ and Topo-X- in ch1 and ch2, profiles can be shown together.

     

    Last edit: Percy Zahl 2015-04-27
  • Ben Ouma

    Ben Ouma - 2015-04-29

    Hi Percy,
    Thanks for your last response. You have been of great help in our progress. We are now able to manipulate our scans for like a single line and observe the trace and retrace lines on the same channel.But one more concern;

    Is there a way the channel can show only the current trace and retrace lines instead of the cumulative trace and retrace lines. Its a little confusing while trying to optimize the scan parameters for our set-up.

    Secondly, on the SR-DSP PAC window (Phase/Amplitude convergent detector control), there is Exec-Amp which is kinda stuck at some constant value. What does the parameter Exec-Amp mean as far as the PLL is concerned?

    Kindly assist.

    Best Regards,
    Ben

     
  • Percy Zahl

    Percy Zahl - 2015-04-29

    Hi!

    yes. See preferences-> User/Red(Blue)LineHistoryColors

    the list of (valid xcolor names) determines the colors used and history length (# past profiles).

    So for only one, simply just put "red" for the RedLine and "blue" for the BlueLine. (Or what ever color you like)

    ExecAmp (monitoring only) is showing the current "SineVolume" if the Amplitude Controller is enabled, else obviously it is adjusted by / equal to the SineVolume setting manually. It is only updating you you check "monitoring". But to safe USB bandwidth, only enable monitoring when you need it.

     
  • Ben Ouma

    Ben Ouma - 2015-04-30

    Dear Percy,

    Pretty working well, thanks a lot.

    Now I have been observing this for along time now just out of curiosity, what does SEGMENTATION FAULT (CORE DUMPED) means and is there a precautionary measure one can take to avoid the SEGMENTATION FAULT (CORE DUMPED) anytime a change is made on the preferences or in some particular scan parameters?

    This is because when you have engaged the surface and you click on the scan button, everything just disappears except for the 2 terminal windows.

     
  • Percy Zahl

    Percy Zahl - 2015-04-30

    At start scan? That's new to me. Can you get me more details when exactly and under what circumstances/settings/ect.?

    Seg Fault. is a very generic error for any wrong/not allowed/out of range/etc. memory access attempt.

    There is one old know issue with the "life refresh" or "auto plot" of profiles while doing probing/sts etc. -- but only on certain older motherboards/chipsets I observed this in the past more or less randomly and it's still puzzling.

     
  • Ben Ouma

    Ben Ouma - 2015-05-05

    Dear Percy,
    Thank you for your last response. We changed our machine but still experienced the SEGMENTATION FAULT (CORE DUMPED) on two occasions:

    1. We rotated the scan to 45 degrees and scanned it worked OK but when we changed to -45 degrees and clicked the scan button, everything disappeared.

    2. A similar experience was also noted when we increased the scan speed then pressed a scan button, the window disappeared again. So we have adopted changing the scan speed real time.

    Secondly I have a question about the BW- set up parameters for PLL;

    1. In PAC/PLL window what is the optimum Bandwidth for the phase (BW-Phase) and amplitude (BW-Amp) that will guarantee a good enough Z response?
      When we used a large value of say 4000 for the BW-Phase, we don't seem to obtain any plot of dF but when we use a BW-Phase of say below 30 we are able to obtain the topography. How does the lower values of the BW-Phase affects the Z-response?

    Kind Regards,
    Ben

     
  • Ben Ouma

    Ben Ouma - 2015-05-14

    Dear Percy,

    We are making good progress in our gxsm based AFM but something is worth noting. The topography images for the TRACE and RETRACE seem to be mirror images of each other (retrace data seems to be collected in reverse) for 2D images. Could there a way out to solve this problem? This don't seem to be the case for 1D profile image. Kindly assist.

    Thanks for your help till now.

    Regards,
    Ben

     

    Last edit: Ben Ouma 2015-05-15
  • Camiel van Hoorn

    Hi Ben,

    I experienced the same problem and figured out that when you open the images in an other program like Gwyddion they look normal.

    Camiel

     
1 2 > >> (Page 1 of 2)

Log in to post a comment.