| 摘要 |
PROBLEM TO BE SOLVED: To provide a production method of the porous glass preform which is not adversely affected even when soot falls on a light source and has good properties with respect to optical fiber drawn from the preform, at the time of producing a porous glass preform by a VAD method and also to provide a device for the production. SOLUTION: This production comprises depositing soot that is synthesized by an oxyhydrogen-flame hydrolysis of a gaseous glass raw material, on a target in a chamber 5. In the method, a light source 3 for picking up an image of the tip of a preform is provided with a cover 8 to prevent soot 6 inside the chamber 5 from being stuck to the light source 3. This device has such a light source 3 that is provided with such a cover 8 placed inside the chamber 5. |
