| 摘要 |
<p>This invention relates to a device for removing a powdery substance accumulating in a tubular back portion (2) of an optical fiber preform (1) during the manufacture thereof, comprising a screw structure (3) following the inner surface of said tubular back portion (2). In order to provide an efficient removal structure which does not affect the preform mechanically or in any other way, the screw structure (3) according to the invention comprises a gas conduit (4) provided with orifices (5) opening towards the open end of the tubular back portion (2). Preferably the structure is a pipe (3) wound in the form of a spiral.</p> |
