| 摘要 |
PROBLEM TO BE SOLVED: To provide a scanning probe microscope which can always keep vibration amplitude of a cantilever being fixed. SOLUTION: An output signal Asinωt of a phase control circuit 11 is input to an amplifier 13. A signal conversion circuit 14 converts the signal from the amplifier 13 into the specific amplitude signal Bsinωt. A RMS-DC circuit 16 detects the amplitude of the signal from the amplifiers 13 and outputs the detected amplitude as DC voltage Arms. The output Arms of the RMS-DC circuit 16 is inverted by an inversion amplifier 17 and an error amplifier 18 outputs a signal Verr=G(Vref-Arms). A multipliers 15 multiplies the output of the error amplifier 18 by the output of the signal conversion circuit 14 and outputs the signal Vout=BG(Vref-Arms)sinωt. The output signal Vout of the multiplier 15 is supplied through an attenuator 20 to a piezo element 7, and it is used as an excitation signal of the cantilever 5.
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