| 摘要 |
PURPOSE:To obtain a preform of optical fiber having stabilized characteristics continuously measuring the concentration and flow rate of a raw material gas fed to a reaction system and feeding the product of the concentration and the flow rate back to the raw material feeding system. CONSTITUTION:A carrier gas (e.g. helium) is fed into a raw material vaporizer 1 composed of a saturator, etc., capable of feeding the carrier gas into a liquid raw material, producing bubbles and saturating the gas in the bubbles with the vapor of the raw material liquid to vaporize the raw material (e.g. silicon tetrachloride). The flow rate of the raw material gas fed to the reaction system is measured with a flowmeter 3 and the flow rate of the raw material gas branched with a branching device 2 is measured with a flowmeter 4. The branched raw material gas is then fed to a gas mixer 6 and mixed with a diluting gas (e.g. helium) and the flow rate is measured with a flowmeter 5. The concentration of the objective component is measured with a concentration measuring instrument 7. The concentration of the raw material gas fed to the reaction system is calculated from the aforementioned data with a controller 8 and feedback control to the vaporizer 1 is carried out so that the product of the concentration and flow rate may be constant. |
