Coupling independent fiber optic tilt and temperature sensor based on chirped tapered fiber Bragg grating in double-pass configuration

A simple fiber optic inclinometer based on linearly chirped fiber Bragg grating written in both fused taper transitions is presented. Specially designed and inscribed fiber gratings reveal two selective reflection bands, where only one is sensitive to bending and the other is used as a reference. Thus, the presented inclinometer is insensitive to coupling efficiency variations when the sensor head is reconnected to the measurement setup. Furthermore, the inclinometer is characterized by a 0°-70° operating range, 1° resolution and similar sensitivity. In the presented configuration, the inclinometer can operate as a temperature independent strain sensor as well as simultaneously measure tilt and ambient temperature.