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cavity length between fiber end and cantilever) is located at the midpoint
between minimum and maximum of the interference signal.
Adjust ADC1 to the WP by tuning the dither piezo voltage, i.e. DAC1, in the
‘DACs’ window.
2. Finding the resonance frequency f
res
of the cantilever:
In non-contact mode, the cantilever is excited at its resonance frequency f
res
with the an AC voltage A
exc
. To deduce f
res
, the excitation frequency is swept
while measuring the oscillation amplitude (and the phase) of the cantilever.
The excitation amplitude and all demodulation settings are made in the
‘Lock In’ widow. The frequency sweep is done in the ‘Calibration’ window.
High Frequency box:
Amplitude (pp): 10-200 mV (@RT); 1-20 mV (@LT)
This sets the excitation amplitude
Frequency:
This frequency will be deduced from the
calibration
For ‘Demodulation’ parameters, choose:
Sensitivity Range: 1-2 V (maximum oscillation
amplitude Aosc)
Phase Shift:
leave 0 or set an offset phase so that the
phase signal is 0 at resonance.
Integration time: set to 100 µs – 1 ms
Leave the Preferences value set to 1.
Calibration:
Frequency range (Start - End):
45 kHz – 95 kHz
(depending on the cantilever)
Data Points:
500-5000
Data Point. Avg. Time:
2.5ms
Содержание attoAFM I
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