A new method to measure the oscillation of a cylindrical cantilever: "The laser reflection detection system"

A new optical detection system for measuring the oscillation of cylindrical cantilevers has been designed. A laser beam is directed perpendicularly to the oscillating plane and is focused on the curved surface of the vibratin g probe. The surface reflects the light and a second lens refocuses it onto a two-segment photodiode. The sensitivity of this method lies in the fact that a small displacement of the probe produces a large angular deflection of the reflected laser. Applications of this new system are presented in or der to demonstrate its reliability, accuracy, sensitivity, and the possible use in a shear force microscope. All the results are finally analyzed by m odeling the motion of the cantilevers using harmonic oscillator theory and the continuous model for oscillating bars. The agreement between experiment al data and models is well inside the experimental errors confirming the po ssibility of using this system to accurately study the dynamics of cylindri cal cantilevers. (C) 2000 American Institute of Physics. [S0034-6748(00)003 03-8].