A novel fiber bundle configuration for concurrent improvement of displacement range and sensitivity of self-referenced fiber optic displacement sensor

In this paper, efforts done towards simultaneous improvement in linear displacement range and sensitivity of self-referenced fiber optic displacement sensor (FODS) are reported. A comparative study of three different configurations of self-referenced FODS having same geometrical structure has done. All configurations contain one transmitting fiber and two receiving fiber groups. The self-referencing is effected by taking the ratio of outputs of second to first receiving group. A transmitting and a receiving fiber in a first receiving group are same. In type I configuration, the second receiving group has three optical fibers are collinear. In type II configuration, the second receiving group has an optical fiber having core diameter three times to transmitting fiber. In type III configuration, the second receiving group has seven optical fibers which are arranged in a circular fashion. In type I and III configuration, all optical fibers are identical and the output of second receiving group is taken as a sum of outputs of receiving fibers. The simulations and experimentations are carried out for all configurations. The obtained linear displacement ranges are 2.1, 1.3 and 2 mm with sensitivities of 0.42, 1.25 and 1.31 mm−1 having less than 2% nonlinearity error for type I, II and III configurations. Type III configuration offers improved linear displacement range and sensitivity as compared to type I and II.