Micro force Measurement by an Optical Method

TL;DR

This paper explores a novel optical method for microforce measurement using stress-induced frequency shifts in a monolithic Nd:YAG laser, enabling precise force detection through polarization beat frequency analysis.

Contribution

It introduces a new optical approach leveraging crystal stress effects in Nd:YAG lasers for microforce measurement, providing a potentially highly sensitive and accurate technique.

Findings

Force-induced frequency shifts of several gigahertz observed.

Differential changes in orthogonal polarization modes enable stress quantification.

Method offers a new optical tool for microforce sensing applications.

Abstract

We discuss the application of stress-induced changes in the crystal of a monolithic Nd:YAG laser as a possibility for microforce measurement. In fact, application of an unknown force on the resonator-amplifier-crystal can lead to a several gigahertz change, depending on the force intensity, of the laser frequency. In addition, the changes rates of the two orthogonally polarizations of the same mode with applied force are different. Hence, the strength of the applied stress can be deduced from measurement of induced change in the beat frequency between the two polarizations or between the fast mode (mode polarized in the orthogonal direction of the stress) and a reference frequency.