Fiber-optic sensing system for measuring curvature

A fiber-optic sensing system for measuring a curvature in an elongated cavity of an object, said system comprising:

• a light source for emitting a light signal;
• a coupler, for coupling the light signal emitted by the light source into a sensing optical fiber and a reference optical fiber;
• the sensing optical fiber, the distal section of the sensing optical fiber is inserted into the cavity of the object which curvature is to be measured;
• the reference optical fiber, being bundled with the sensing optical fiber, wherein when the distal section of the sensing optical fiber is inserted into the cavity of the object and suffer a bending thereof, the reference optical fiber is not inserted into the cavity of the object;
• a first light signal reflecting device, disposed at a distal end of the sensing optical fiber, for reflecting the attenuated light signal;
• a second light signal reflected device, disposed at a distal end of the reference optical fiber for reflecting the light signal emitted by the light source as a reference signal;
• and
• a signal processing device, for measuring the attenuated reflected light signal and the reference signal through the coupler, and calculating the curvature in accordance with the energy of the attenuated and reflected light signal normalized with the energy of the reference signal.