| 摘要 |
PURPOSE:To obtain a liquid detecting optical fiber which shortens the detection time of a liquid without degrading the mechanical strength by providing a porous clad on the outside circumference of a core. CONSTITUTION:In a liquid detecting optical fiber 1, the outside circumference of a core 2 consisting of quartz glass or the like is coated with a porous clad 3. The porous clad 3 is formed with foamed plastics with connected bubbles, a net of fine meshes consisting of fibers, a nonwoven faleric, or the like. It is desirable that a refractive index n1 of the core 2 is higher than a refractive index n2 of the porous clad 3; and though the core 2 is brought into contact with air in parts of pores of the porous clad 3, the light is hardly leaked in a normal state because air has a refractive index lower than that of the core 2. In case that there is a probability that the contacting of the core 2 with air causes characteristic degradation, a thin film coating 2A consisting of materials whose refractive index is higher than that of the porous clad 3 is provided on the surface of the core 2. this liquid detecting optical fiber is laid along a place where the leakage of a liquid should be detected. |
