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Hello Everyone.
What information can we extract from 'Deflection Error' image during contact mode AFM.
I believe it represents the difference between tip deflection and peizo-movement.
Thanks in Advance.
Palash
Hi Palash,
Yes, one can absolutely use it as a qualitative map of the surface. It is often useful in particular when you want to see the smaller "wrinkles" that may be less visible in the actual Height image.
As to what the deflection error represents: It is the difference between actual cantilever deflection and deflection setpoint. As the response of the feedback loop is finite, this error will be finite and will be larger for a larger slope in the fastscan direction. So you can use it as a qualitative measure for how "steep" the sample is in that direction.
Hope this helps.
Best,
Thomas
Hi, my understanding of the Deflection Error signal is the following:
1) when you are in Z-Closed Loop (Gain>0) , as you say "it represents the difference between tip deflection and peizo-movement". This it gives information about the derivative of the topography
2) when you are in Z-Open Loop (Gain=0) you get a map of the topography (in Volts). Here the piezo does not move, just the tip does. To calibrate it you might make a force curve on a hard sample.
hope it helps,
Luis
Hi Luis,
Thanks for the reply.
Just for curiosity - the deflection error image is so much sharper and gives us a nice 'feel' of the surface features (as compared to height data).
Why dont we then use it to (qualitatively) represent surface topography?
Best -