| 摘要 |
<p>PURPOSE:To make it possible to measure a temperature that a cable receives and to detect the receiving site, by providing an optical fiber having an optical waveguide which guides no light when it reaches a prescribed temperature, and by measuring the attenuation of an emission of a light from the cable and the distance thereof. CONSTITUTION:An optical fiber 1 having an optical waveguide formed of a core 2 and a clad 3 can execute prescribed light transmission at a normal temperature, since the refractive index of the core 2 is large while that of the clad 3 is small. As the refractive index of the core 2 turns small. As the refractive index of the clad 3 large, thus the refractive indexes of these two elements approximating to each other, with a rise in temperature, the amount of light transmission attenuates, and at the time point when the refractive indexes of the two elements become equal, the light turns not to be guided. When the temperature lower from this state, the refractive index of the core 2 turns large and that of the clad 3 small therewith. As the refractive indexes of the two elements become apart from each other, the amount of light transmission increases and it returns to the initial state at the normal temperature. By adjusting the content of a titanium oxide appropriately, the temperature whereat the refractive index of the core 2 becomes equal to that of the clad 3 can be determined arbitrarily.</p> |
