A technique that is easy to implement and sensitive for measuring late
ral oscillation amplitudes of optical fibers on the nanometer scale fo
r shear-force microscopy is described. The measurement system analyzed
here is based on using the optical fiber tip as a cylindrical lens to
focus and deflect a detection beam. It is shown that for our experime
ntal arrangement, this technique is at least 2.5 times as sensitive as
merely shadowing the edge of such a beam, as in most commonly used co
nfigurations. As a result, oscillation amplitudes of the order of 2-3
nm may easily be measured. An advantage of this system is that absolut
e vibration amplitudes are easily measured. A simple geometric model i
s used to describe the operation of the system. (C) 1997 Optical Socie
ty of America.