Abstract: The invention includes an apparatus (110) and method (152) for determining a deformation (170) of a three-dimensional, flexible structure in the form of a tubular construct (112) with a minimum of optical waveguides. An optical waveguide (116) is introduced into the tubular construct (112), where the optical waveguide (116) extends as a helical winding (118) within the tubular construct (116) and has a multiplicity of strain measuring means (126). The configuration of the apparatus and method performed reduces the average material load of the strain measuring means and improves resolution and measurement range of the sensor (optical waveguide) while maintaining readout frequency of the strain measurements.

Abstract: The invention relates to an apparatus (110) and a method (152) for determining a deformation (170) of a three-dimensional, flexible structure in form of a tubular construct (112). Here, at least one optical waveguide (116) is introduced into the tubular construct (112), wherein the optical waveguide (116) extends in form of a helical winding (118) within the tubular construct (116) and has a multiplicity of strain measuring means (126). The apparatus (110) further comprises at least one evaluation device (130) which is configured to determine the deformation of the tubular construct (112), in particular in relation to an axis, surface and/or volume of the construct (112), from measurement values (154) from the multiplicity of strain measuring means (126).