New structure for multipoint temperature-independent strain sensing system employing optical power detection scheme

A new structure of multipoint temperature-independent strain sensing system with dual fiber Bragg gratings as sensors is proposed. An optical switch is employed to bridge between the detection site and multiple far ends where fiber Bragg grating sensors are located. A voltage divider is used in the proposed optical power detection scheme to resolve the measurement instability caused by the power fluctuation of the light source in a long term and the nonflat spectrum of the light source. This new detection scheme is demonstrated to have a measurement linearity and resolution of ±0.25% and 0.4 μS, respectively.