Abstract
A nonoptical technique for tip-sample distance control in scanning near-field optical microscope (SNOM) is proposed and demonstrated. A tuning fork was used both as a dither and a sensor with high Q factor. The time-gating technique was employed as a scheme for vibrating the tip and sensing the tip-surface distance with the same fork. The time-gating scheme used could potentially be applied for studying various surface relaxation processes with submillisecond resolution.