Small-Force Measurement by Photo-Elastic Transducer

Abstract

The use of stress-induced changes in a crystal of a monolithic solid-state laser by external force as a way for micro-force detection and measurement is described. In fact, the application of an unknown force on the resonator-amplifier crystal of a solid-state laser leads to a measurable change in the frequency of the beat note associated with the orthogonal polarisation components of the oscillating laser mode. Here we report our first measurements of the sensitivity of a photo-elastic force sensor, realised with a monolithic (4 × 4) mm plano-convex cylindrical crystal, and compare them with the results obtained by other authors for different configurations and dimensions of the laser sensor. The reported results are in a good mutual agreement but show notable discrepancies with theoretical predictions, especially for high sensitivities obtained when the dimensions of the laser sensor are small.

Miniaturized Nd-YAG laser as photoelastic transducer for small forces sensing

“…La méthode, fondée sur l'effet photoélastique dans un laser, consiste à convertir une force mécanique en une fréquence. Même si elle a déjà fait l'objet d'un certains nombres de publications [6][7][8][9] …”