PRECISE FORCE MEASUREMENTS BY PHOTO-ELASTIC LASER CRYSTALS IN THE TIME /FREQUENCY DOMAIN

W. Holzapfel, M. Suske

Abstract

Mechanical forces can be sensed over a very broad input range (10 nN up to 100 kN) with high resolution and linearity by applying the photo-elastic effect in small solid-state lasers (diode-pumped Nd:YAG crystals). The input force vector modulates the optical frequency of the laser crystal. In our experiments sinusoidal, pulse, and transient forces are generated by a PCT drive in a special dynamic test set up. By simple autodyne detection of the laser beam and concurrent signal processing of the electrical beat signal, we can measure sinusoidal forces from DC up to 100 kHz modulation frequency. Frequency counter measurement of pulse forces can be performed within few microseconds. By digital filtering, the final value of structure-induced transient forces can be predicted with high precision in milliseconds.

Keywords

force measurement, force-to-frequency conversion, photo-elastic effect

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PWC-2006-TC3-029u.pdf

DOI

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IMEKO TC

TC3 - Measurement of Force, Mass, Torque, and Gravity

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