| 摘要 |
PURPOSE:To prevent the defective deposition of glass soot, and obtain the titled preform having high quality, by shifting a burner for forming the outer circumference of the preform according to the radial growth of the preform, thereby keeping the gap between the tip of the burner and the outer circumference of the preform at a nearly constant distance. CONSTITUTION:In the forming of an optical glass preform 4, the core part 3 of the optical glass preform 4 is formed by depositing glass soot produced by the burner 2. Separately, the glass soot formed by the second burner 3 is blasted toward the outer circumference of the core 5 and deposited to form the outer circumferential part of the optical glass preform 4. In the above process, the burner 3 is shifted along the direction crossing (perpendicularly or nonperpendicularly) with the axial line of the preform 4 to keep the gap between the tip of the burner 3 and the deposition surface (outer surface of the preform) at a definite distance. The glass soot can be deposited in high efficiency, and the state of the deposited glass soot, e.g. the gas composition, deposition density, etc. can be stabilized. An optical glass preform having high quality and free from cracks, etc. can be manufactured by this process. |
