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hello,
I am using an NI DAQ USB 6356 for reading the height signal at output 1 and amplitude (Tapping Mode) and deflection (Contact Mode) at output 2 of the Nanoscope 5 controller. Can you please tell me how I can determine the callibration constants to convert these measurements from volts to nanometers?
Secondly, I have noticed that in tapping mode AFM I set the amplitude set point to be 250mV, but after engaging the Multimode software changes the set point to be a little higher, normally between 350mv and 400mV. What is the reason for this change?
Best regards,
Umar Khan.
Umar,
Deflection is of course in Volts until calibrated by you. That calibration is called "deflection sensitivity" and will convert e.g. the delfection from Volt into length. The procedure for deflection sensitivity is described in the manual and yield a conversion factor. Just apply that factor to your external control system as you wish.
You select a target amplitude in the software. Now, during engage the approach algorythm checks and adjusts these settings to make sure you are really on the surface. It is in reality a rather involved process that the system goes through in order to avoid false engages. Parameters that control these adjustments can be found in the engage menu in your nanoscope software.
Stefan