The tuning fork as sensor for dynamic force distance control in scanning near-field optical microscopy

The dynamic force distance control for scanning near-field optical microsco py on the basis of a tuning fork as piezoelectric force sensor is remarkabl y sensitive. In order to gain a better understanding of this sensitivity th e vibrational properties of the tuning fork are modelled within the framewo rk of two coupled harmonic oscillators. As a result, the effective force co nstant of the tuning fork at resonance frequency is determined. Furthermore , the influence of the additional mass by the attachment of the near-field probe is investigated.