Sensing Apparatus and Method For Detecting Strain between Fiber Bragg GratingSensors Inscribed into an Optical Fiber

摘要

A sensing apparatus and related method for sensing strain between fiber Bragggrating sensors inscribed in an optical fiber. The fiber is inscribed with a first fiber Bragg grating sensor and a second fiber Bragg grating sensor. A strain detection unit detects strain between the first fiber Bragg grating sensor and the second fiber Bragg grating sensor based on the optical propagation time of light projected into the fiber and reflected by the first fiber Bragg grating sensor and the optical propagation time of light projected into the fiber and reflected by the second fiber Bragg grating sensor. More specifically, light projected into the fiber is modulated with an RF signal. A phase change of the RF signal is determined from the light projected into the fiber and reflected by the first fiber Bragg grating sensor and from the light projected into the fiber and reflected by the second fiber Bragg grating sensor. The phase change of the RF signal is related to the optical propagation time of light projected into the fiber and reflected by the first and second fiber Bragg grating sensors. The strain between the first and second fiber Bragg grating sensors is then determined from the detected phase changes.