Relationship Between the Crack Width and the Loss in Optical Fiber in Fiber Optical Crack Sensors

To obtain the characteristics of fiber optical crack sensors and to simplify their design, the bend loss of multiple mode optical fiber is analyzed using the ray theory. Several important parameters are calculated: relationship between the crack width and the optical loss, influence of the angle between the fiber and crack, the influence of numerical aperture to sensors. The theoretical analysis accords well with the experiment results.