| 摘要 |
PURPOSE:To eliminate the variation of the distribution of refractive index and improve the yield, by controlling the heating temperature of a glass tube with a burner according to the heat accumulated in the glass tube by heating. CONSTITUTION:The burner 6 reciprocates along the length of the glass tube 1, and heats the outer circumference of the tube 1 during the rightward motion. Glass layers are deposited in layers to the inner surface of the glass tube 1 by feeding the raw material gas into the tube 1 and heating the tube 1 with the burner to effect the reaction and decomposition of the raw material gas. In the above process, the fire of the burner 6 is intensified during the motion from the F point to the B point to heat the glass tube 1, and is weakened during the motion from B to F to cause the spontaneous cooling of the tube 1. The surface temperature of the glass tube 1 is detected by the temperature detector 11 moving integrally with the burner 6, and the heating temperature of the burner 6 is controlled according to the detected temperature. |
