| 摘要 |
<p>A device for contracting a hollow substrate tube made of quartz glass, whose interior is provided with one or more glass layers, which may or may not comprise one or more dopants, into an optical preform, comprising a heat source which is movable relative to the longitudinal direction of the substrate tube, wherein an insert tube is present in the interior of the hollow substrate tube, at one end thereof, which insert tube is provided with a central opening, through which opening a gas can be passed and be supplied to the interior of the substrate tube.</p> |
