Highly Sensitive FBG Based Tilt Sensor Using PM-IM Conversion and EFD Interrogation Technique

Tilt sensors are essential measurement devices to identify the degree of deviation from the reference plane. They are extensively employed in underground drilling, level determination for instrumentation and mechanical guiding, geophysical observation, biomedical research, etc. Fiber Bragg gratings (FBG)-based inclinometers have marked their presence due to their superior performance and ability to work under harsh conditions to their electronic counterparts as well as other fiber optic sensors. FBG-based inclinometers require optical spectrum analyzers and interrogators for observing wavelength encoded data. Due to the limited resolution of these equipment, it is difficult to develop an inclinometer with very high sensitivity and resolution. Hence, an interrogation technique that utilizes edge filter detection and phase modulation to intensity modulation (PM-IM) conversion phenomena is used to develop an inclinometer with higher sensitivity and accuracy. A detailed theoretical discussion along with its experimental validation is conducted in this manuscript. The proposed system is simple in design and easy to implement, with a very high resolution of 0.00072 degrees and an accuracy of 0.083 degrees. The results have shown a high degree of linearity in a particular sensing range with good repeatability, making the system a reliable candidate for industrial applications.

Automated summary

This paper presents a fiber Bragg gratings (FBG)-based inclinometer with high sensitivity and accuracy. It utilizes an interrogation technique that employs edge filter detection and phase modulation to intensity modulation (PM-IM) conversion to achieve higher sensitivity and resolution.