Integrated Optical Deformation Measurement with TIR Prism Rods

In this paper, a novel optical measurement principle for deformation, especially torsion, is presented. A laser beam is guided via total internal reflection (TIR) in a prism rod. Every single reflection causes an increasing change in the beam path, which can be measured by its effect on the outcoupling position of the laser. With a diameter of the prism rod of [Formula: see text] and a length of [Formula: see text] , the system achieves torsion sensitivities between [Formula: see text] and more than [Formula: see text] , depending on the actual torsion angle [Formula: see text]. A decency level of sensitivity is defined for comparison, which is exceeded by a factor of [Formula: see text] at [Formula: see text]. The presented principle of TIR prism rods can be adapted to measure different load cases. Using two laser beams, bending and torsion can be distinguished and combined load cases analyzed. The resulting system can be integrated into machine elements, such as screws, to perform condition monitoring on mechanically loaded components.