Method for determining the curvature and/or torsion of an optical waveguide

A method for determining a curvature and/or torsion of an optical waveguide of a fiber-optic sensor comprising an optical waveguide having an axial direction oriented in a light propagation direction and a radial direction oriented perpendicular thereto, wherein the optical waveguide has a core, which extends centrally in the axial direction and runs at least substantially over the entire length of the optical waveguide, for conducting light, and a cladding, which surrounds the core in the radial direction, and wherein a section of the optical waveguide extends in the axial direction and has a plurality of Bragg gratings including a first Bragg grating and a second Bragg grating, which are introduced therein and extend through a common cross-sectional plane, situated in the radial direction, through the optical waveguide, wherein the Bragg gratings are inserted in the core and/or on a boundary between the core and the cladding and/or in an inner edge region of the cladding within an evanescence region of the light, the method comprising:

• providing reference data of intensities of reflected light portions of light coupled into the optical waveguide,
• measuring a light intensity of a reflected portion of light coupled into the optical waveguide, the optical waveguide having a deformation to be determined, and
• determining the deformation by comparing the light intensity with the reference data, the first Bragg grating having a different grating constant than the second Bragg orating.