Impact of Distance Between Twin Receiving Fibers on Sensitivity of the Optical Fiber Displacement Sensor

The impact of the distance between the receiving fibers on the sensitivity of the twin receiving fiber displacement sensor based on the intensity modulation technique has been investigated. The results are obtained using theoretical analysis and experimental investigations. They show that the dependence of the sensitivity of a receiving fiber’s light intensity difference <inline-formula> <tex-math notation="LaTeX">$ B - A$ </tex-math></inline-formula> on the distance between receiving fibers is a nonlinear nonmonotonic function with an extreme point, at which the sensitivity is maximal. The sensitivity of the light intensity ratio logarithm ln<inline-formula> <tex-math notation="LaTeX">$(B/A)$ </tex-math></inline-formula> increases with the distance between the receiving fibers. The sensitivity of the ratio <inline-formula> <tex-math notation="LaTeX">$(B - A)/(B + A)$ </tex-math></inline-formula> can increase or decrease with the distance between the receiving fibers depending on the position of the emitting fiber. In practical applications, the receiving fibers in twin receiving fiber displacement sensors are placed close together. However, the obtained investigation results show that the sensitivity of the twin receiving fiber displacement sensor based on the intensity modulation technique can be improved up to 4–5 times if the appropriate distance between the receiving fibers is introduced.