Method for increasing shear-force detection sensitivity with uncoated fiber tips

Abstract

A technique that is easy to implement and sensitive for measuring lateral oscillation amplitudes of optical fibers on the nanometer scale for 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 experimental 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 configurations. As a result, oscillation amplitudes of the order of 2-3 nm may easily be measured. An advantage of this system is that absolute vibration amplitudes are easily measured. A simple geometric model is used to describe the operation of the system.