| 摘要 |
PURPOSE:To obtain a heat-resisting image fiber tolerant to use in a high temperature atmosphere for monitoring, observation, etc., in a furnace, by providing a flexible heat-resisting coat on the secondary outward coat of optical fibers bundled with a jacket by using an interposed heat insulating material. CONSTITUTION:Many optical fibers are bundled with the jacket 2 made of a quartz tube to constitute a picture element part 1, on which a primary coat 3 of silicone resin for ensuring fiber strength and a PVC secondary coat 4 as protective coating are provided. Further, flexible heat-resisting coating 6 is provided around the secondary coat 4, and a heat insulating material 5 is packed between the heat-resisting coating 6 and secondary coat 4. As the heat-resisting coating 6, a material which has flexibility and heat resistance, e.g., a flexible pipe is employed, and a metallic pipe having excellent heat conductivity is generally used, but when in-use temperature is relatively low, heat-resisting plastic is usable. Further, the heat insulating material 5 uses asbestos, etc. |
