Temperature-independent FBG-type torsion sensor based on combinatorial torsion beam

A new method of temperature-independent torsion measurement based on a combinatorial torsion beam is proposed and demonstrated. One half of the unique sensing fiber Bragg grating (FBG) is linked to a solid torsion beam, while the other is fixed to a less rigid part of the air-hole torsion beam. The spectral response of the FBG is split into two spectral peaks and the spectral separation of these peaks corresponds to applied torsion. In the measuring range from -40/spl deg/ to +40/spl deg/, torsion angle sensitivity is about 0.092 nm/degree and torque sensitivity is 2.076 nm/Nm, respectively.