| 摘要 |
PURPOSE:To obtain a defect-free molding by forming a porous glass body for a core of a prescribed molding material with forming molds for the core by internal pressure reduction and external pressurization and molding a clad on the outer periphery thereof with forming molds for the clad. CONSTITUTION:A molding material 53, such as fine particle of doped SiO2, is packed into a molding space 52 and is deaerated; thereafter, a pressure medium 49 is injected therein. A cylindrical mold 41 for molding is then pressurize The cylindrical mold 41 for molding is shrunk and the molding material 53 is shrunk under the external pressure by the pressure medium 49 and the internal pressure reduction by pump suction. The bubbles included therein are simultaneously removed to mold the porous glass body 54 for the core. The glass body is taken out after the pressures are restored The porous glass body 54 for the core is then disposed into the molding space 74 for the clad and a molding material 75 is packed on the outside periphery thereof. The inside is deaerated by suction and is pressurized by the pressure medium 71, by which the porous glass body 57 for the clad having a uniform bulk density is formed on the outer periphery of the porous glass body 54 for the core, by which the porous glass base material of the quartz system is obtd. |
