Abstract: The present invention provides an optical fiber preform-heating furnace that is simple in its structure and excellent in uniformity of the temperature distribution in a circumferential direction of an optical fiber preform. The optical fiber preform-heating furnace includes a furnace core tube into which an optical fiber preform is supplied; a heater that surrounds the furnace core tube; a pair of electrode connection portions with which the heater is provided and has a face opposing to an outer periphery surface of the furnace core tube; and electrode portions that are disposed to each of the electrode connection portions and connected to a power supply. When a cylindrical heat insulator is disposed between the furnace core tube and the opposing faces, since an outward heat transfer amount from the furnace core tube side through the electrode portion can be reduced, the temperature distribution in a circumferential direction of the optical fiber preform can be improved in its uniformity.

Abstract: A reaction chamber including a reaction chamber in which preform is formed is provided. A cladding burner for forming a cladding of the preform is arranged in the reaction chamber, and a blocking member for suppressing ascending of the air in the reaction chamber is provided above the cladding burner. With this arrangement, abrupt flame-up of a flame containing glass particles produced through the burner is suppressed, the productivity of a preform is improved by accelerated formation of a preform, and the amount of glass particles which may adhere to a wall of the reaction chamber is reduced.

Abstract: The present invention provides an optical fiber preform-heating furnace that is simple in its structure and excellent in uniformity of the temperature distribution in a circumferential direction of an optical fiber preform. The optical fiber preform-heating furnace includes a furnace core tube into which an optical fiber preform is supplied; a heater that surrounds the furnace core tube; a pair of electrode connection portions with which the heater is provided and has a face opposing to an outer periphery surface of the furnace core tube; and electrode portions that are disposed to each of the electrode connection portions and connected to a power supply. When a cylindrical heat insulator is disposed between the furnace core tube and the opposing faces, since an outward heat transfer amount from the furnace core tube side through the electrode portion can be reduced, the temperature distribution in a circumferential direction of the optical fiber preform can be improved in its uniformity.