Scanning/scanner issue with INNOVA AFM (tapping mode)

Eric posted on Thu, Oct 30 2014 2:16 PM

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We have a scanning issue with our Innova AFM.   Everything seems to operate normally regarding aligning the laser and setting everything up, but when we engage under tapping mode it appears as if the scanner is jumping around, especially during scanning and POSSIBLY during the engaging mainly after the piezo scanner starts incrementally trying to engage the sample.

The "jumping around" is very apparent in the video feed through the optical microscope.  I was trying to attach a video of what happens during a full scan (from beginning to end in the video), but anyhow you can see that the AFM tip is stationary but the sample is "jumping" around.  I have attached corresponding height data and a screen shot of our scanning parameters,etc  .

I think it may be useful to mention that we have modified our AFM setup so the AFM head actually doesn't move  at all because it is being used in a near-field scanning optical microscope home-built setup where the AFM head has to be completely stationary (exactly like Markus Raschke's setup in Colorado).  That is fairly well established but is only really done when used with a scattering type NSOM setup. 

Other relevant observations are that previously we have had issues with the AFM tip amplitude being too small and being unstable between different times engaging a sample (some tips seem to have a really low amplitude then after adjusting numerous things, it becomes normal, especially taking the tip in and out).  Otherwise, everything has been operating relatively normally for the past 2 years since I have used it and before that.

We have tried a few things like tightening the screws that hold down cartridge and cleaning out dust from the connection to the head of the AFM. We are looking for more suggestions.  Maybe recalibrating?

Thanks!

 -Eric (UNC-Charlotte- Physics)