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Problem In Multi-mode 8 AFM during Auto tune the cantilever

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Singh posted on Mon, Nov 5 2012 11:07 PM

I am facing the problem during the auto tune of cantilever in Multi-mode 8 AFM system.

Message is coming "Drive amplitude exceeded safe limits while trying to attain target amplitude. Please tune the cantilever to the desired peak before performing the Q control algorithm. If this does not solve the problem, realign or replace the cantilever."

I checked also those possibility by changing the probe holder (TR and EFM), Cantilever (RTESP, SNL etc.) and disabled the sweep frequency, but showing the same problem. Same problem in Peak force/Scanasyst mode (tip is not approaching) measurements. Laser/photodiode adjustment is working properly.  

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Top 10 Contributor
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Bruker Employee

Hi Singh,

This problem occurs when the system is attempting to excite the cantilever with enough drive amplitude to reach the target response amplitude that you have set (or was set by the workspace) in the Autotune window.  There are a few reasons this might occur:

  1. The autotune frequency range is set incorrectly (so that it does not cover the cantilever resonant frequency)
  2. The target response amplitude is very large
  3. The drive signal is being blocked
  4. The response is not measured correctly

For items 1 and 2, check the nominal frequency of the probe that you are using and set the autotune range to the nominal freq +/-50KHz or so.  For target amplitude, type in ".5V" (no quotes).

To cover items 3 and 4, I would suggest unplugging and replugging the cables between the controller and the head  (power everything down first) and remove the Signal Access Module if it is installed.  Visually inspect the cables and make sure you don't have any kinks or bent pins.  Make sure the head is plugged in and the tipholder is clamped in place properly (the electrical connection to the drive is in the clamp for the tipholder).  Also, be sure the laser is correctly aligned on the cantilever, not on the substrate and that the photodiode is zeroed.

ScanAsyst does not require tuning (except on Dimension systems where it is used for the smart engage routine).  So I don't understand how you could be getting that error message on a Multimode in ScanAsyst.

If you still continue to have a problem, please contact tech support so they can do some more in-depth troubleshooting.


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Dear Singh ,

  I am a Phd Student from University of Milano and I am getting the same problem exactly as you mention. Not able to autotune in taping mode while autotuning , says drive amplitude exeeds safe limits . I request you to please let me know what you did to handle this problem. As I am at the end of PhD, it would be so kind, if you reply about the solution as early as possible


Thanking you


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Top 10 Contributor
280 Posts
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Bruker Employee

Hi Sreejith,

Did you try my suggestions in the previous post?  When was the last time you were able to tune correctly?  What has changed since then?


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