Strain measurements on a cantilever beam with fiber bragg grating sensors using a pair of collimators

Fiber bragg grating (FBG) sensors are currently in use in various fields. However, it is difficult to use these sensors to obtain strain measurements at locations where it is not physically possible to connect the fibers to each other. In the present study, we performed strain measurements using many FBG sensors connected to a single optical fiber and a pair of collimators. The single optical fiber connected to the FBG sensors was installed on a cantilevered beam with another optical fiber line connected to a stationary optical interrogator. The two optical fiber lines were connected by a pair of collimators making use of the fact that light travels in a straight line through space. Our experiment demonstrated that the wavelength of the light changed linearly as it passed between the two collimators, and that this change increased with the applied strain. Accurate strain measurements could be obtained by applying a proposed collimator collection factor.