| 摘要 |
PURPOSE:To detect moisture accurately and stably, by winding a wire with a porous moisture absorbing layer on the surface of an optical fiber in a coil to make a moisture sensor. CONSTITUTION:The surface of a core 1 made of methacrylic resin or the like is covered with a clad layer 2 comprising fluorocarbonic resin with a high moisture resistance such as polytetrafluoroethylene and a porous moisture absorbing layer 3 is further evaporated thereon. The optical fiber thus arranged is wound several times in a coil to form a moisture sensor, which is arranged in an atmosphere for the moisture to be detected. Then, when a visible light or an infrared ray is made incident on the incident side 1a of the core 1, a part A thereof is emitted on the emission side 1b thereof after repeated reflection within the core 1 while the remaining part B thereof is transmitted through the core 1 and incident into a film 3 from the layer 2 to be attenuated away. Here, any water 4 in the film 3 reflects the part B of light transmitted to be made incident into the core 1 again and then, the light is emitted on the emission side 1b. Thus, changes in the moisture can be detected depending on increase on increase or decrease in the output of light received with a light receiving device on the emission side 1b. |
