Existence of a stable resonance zone with nearly unchanging vibration characteristics for a near-field scanning optical microscope probe dipped partially into a liquid

The vibration characteristics of a near-field scanning optical microscope (NSOM) probe, whose vibration was controlled by two-nodal-wedge method and tip was partially dipped into a liquid, were investigated theoretically and experimentally. The resonant frequency and the Q value of the NSOM probe were found to remain nearly unchanged irrespective of the dipping depth of the probe, if the probe was kept within a dipping depth range of 0.4∼1.0 mm. With the achievement of a high Q value, the existence of this stable resonance zone implies that bio-samples immersed in a liquid can be accurately and stably measured using a NSOM controlled by using two-nodal-wedge method.