Method and apparatus for the ultrasonic actuation of the cantilever of a probe-based instrument

The cantilever of a probe-based metrology instrument such as an AFM is deflected by directing a beam of ultrasonic energy at the cantilever to apply ultrasonically generated acoustic radiation pressure to the cantilever. The energy is generated by an ultrasonic actuator such as a ZnO transducer driven by a power source such an RF signal generator. The transmitted beam preferably is shaped by focusing, collimation, or the like so that it impinges at least primarily on a region of interest of the cantilever such as the free end. The ultrasonic actuator produces a much better controlled force on the cantilever than can be achieved through the use of a traditional piezoelectric actuator and, accordingly, produces a response free of spurious effects (at least when the cantilever is operating in liquid). It also has a frequency bandwidth in the MHz range.