LIGHT TRANSMISSION BODY AND ITS FORMATION

PROBLEM TO BE SOLVED: To provide an optical fiber rod whose sectional shape is close to a rectangle and the same in the longitudinal direction by putting many cores together, coating each of cores with a clad, joining them mutually, and pressing the cores with specific pressure in their X and Y sectional directions and heating them. SOLUTION: The optical fiber rod 1 cut to specific length is mounted on the upper surface of the lower plate part 11a of a lower metallic mold 11. Then pressure Px (approximately 700 to 800 g/mm ) is applied by an X- directional presser 25 and an upper metallic mold 21 is moved to the left to press the left end surface of its upper plate part 21a and the left surface of the side wall 21b against the right surface of the side wall 11b of the mold 11 and the right end surface of the lower plate part 11a. Heaters 13 and 23 generate heat under the control of temperature controllers 14 and 24 to raise the temperatures of both the molds 11 and 21. Then low pressure (approximately 50 to 100 g/mm ) is applied to the mold 21 by a Y-directional presser 26 and the mold 21 is moved down and made press lightly the optical fiber rod 1.