PRODUCTION OF OPTICAL FIBER

摘要

PURPOSE:To produce optical fiber having a crystalline substance as its core by putting the substance and a first heater into a glass tube; setting a second heater outside the tube; and softening and drawing part of the tube. CONSTITUTION:One end of glass tube 1 is closed to form bottom 2. First heater 3 protected with a quartz glass tube is put into tube 1 so that it may not contact to bottom 2, and granular or powder crystalline substance 5 as a core material is charged into the bottom part of tube 1. Cylindrical second heater 6 having an inside diameter larger than the outside diameter of tube 1 is set coaxially with tube 1 in the vicinity of bottom 2. Substance 5 is heated to a temp. above the m.p. with heater 3, and bottom 2 is simultaneously heated to a temp. above the softening point with heater 6. A metal rod is adhered to bottom 2 and pulled downward with pinch rollers 9 to draw tube 1.