| 摘要 |
PURPOSE:To relieve the working strain of an optical fiber and to decrease the spreading angle of an exist beam by subjecting the optical fiber consisting of metal halide to a heat treatment in a vacuum or gaseous halogen atmosphere. CONSTITUTION:The optical fiber consists of the crystal or mixed crystals of the halide of metal, more preferably halide of Ag, or the crystal or mixed crystals of halide of Tl. The fiber worked to the shape of the optical fiber is subjected to the heating treatment at the temp. below the m.p. of the fiber material in the vacuum, more preferably >=10<-4>Torr vacuum or the gaseous halogen atmosphere of the constituting elements, more preferably under 10<-3> Torr-3atm pressure. For example, an AgBr fiber is put into a quartz glass tube 1 and after the inside of the tube is evacuated, a diametrally reduced part (a) is sealed. A 'Teflon(R)' coated magnet 4 is then dropped to crack a Br ampoule 3 and a separate space part 2 is heated. Gaseous Br2 is introduced into the tube 1 and thereafter the diametrally reduced part (b) is closed. Such tube 1 is put into a heating furnace and is heat-treated. |
