PRODUCTION OF PREFORM FOR OPTICAL FIBER

摘要

PURPOSE:To improve both measuring accuracy of densities in a deposit layer and accuracy of diameter ratio of the core to the clad by measuring the densities of plural parts in the radial direction of a fine glass particulate deposit layer. CONSTITUTION:A dehydrated and vitrified optical fiber preform substrate 4 consisting of a core (4A) and a clad (4B) is reciprocated in the shaft center direction in a vessel 1 while being rotated. The resultant fine glass particulate deposit layer 6 is then exposed to radiation emitted from a radiation source 9 through windows 11 and 12 so as to cross the deposit layer 6 in the radial direction. The radiation penetrated the deposit layer 6 is then detected with a detector 11 to measure densities of the respective positions in the radial direction of the deposit layer 6. The whole volume of the deposit layer 6 is determined from the densities and dimensions in the radial direction. The fine glass particles are deposited until the above-mentioned values attain a prescribed value.