| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a glass preform with high accuracy by suppressing the temperature rise of a sensor section for detecting a deposition surface of glass particulates. SOLUTION: A deposition treatment of the glass particulates is performed by receiving the laser beam emitted from a laser element 12 by a laser photodetector 14, thereby controlling the deposition surface to a fixed position at all times. The photodetector 14 is provided with a filter 17 for absorbing the heat rays generated from the flame, etc., of a burner 13 and a heat resistant plate 16 using a heat resistant material to prevent the temperature rise thereof. Cooling gas is blown to the photodetector 14 to cool the same. The malfunction by the temperature rise of the sensor section can be prevented by such configuration, by which the position control of the deposition surface can be executed with reliability and the manufacture of the glass preform with the high accuracy is made possible. COPYRIGHT: (C)2004,JPO
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