A FAST AND VERSATILE SCAN UNIT FOR SCANNING PROBE MICROSCOPY

In scanning probe microscopy (SPM), the image acquisition time is usua lly very long because of the limited speed with which the scanning dev ice can trace the topography of the specimen under feed-back control. This limitation is often brought about by the natural frequency of the scanner in the direction perpendicular to the sample plane that confi nes the usable bandwidth of the feed-back loop. In this paper, we pres ent a piezo-ceramic scanner that provides a large scan range and at th e same time allows for adjustment of the probe-to-sample distance fast er by about one order of a magnitude than a conventional setup. This i s achieved through the combination of a large single tube scanner that provides a high scan range and a small piezo element for swift motion in the direction perpendicular to the sample plane. The natural frequ ency in this direction lies at about 275 kHz. We outline the design co nsiderations to avoid disturbing excitation of the scanner through the fast piezo element.