TIP GUIDE DEVICE FOR OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To achieve a sufficient cooling function of a tip guide to be used in an apparatus for measuring temperature in molten metal by a method wherein an optical fiber is fed into the molten metal being guided by the tip guide and heat radiation light in the molten metal is brought in from the tip of the optical fiber to be guided into a radiation thermometer. SOLUTION: A tip guide 19 is built in a triple structure. In other words, a first cooling medium (e.g. air) is blown into an inner cylinder 31 through which passes an optical fiber from a nozzle 51 and deprives ambient heat by adiabatic expansion to be discharged at a tip opening 57. A second cooling medium is fed into a middle cylinder 33 and an outer cylinder 35 arranged concentric with the inner cylinder 31 at a feed port 48 and discharged at a discharge port 50.