Optical fiber preform manufacturing method

Abstract

The invention discloses an optical fiber preform manufacturing method which comprises the following steps: an upper laser of a first laser instrument measures the diameter d of a sandwich layer, a lower laser measures the top end shape P of a powder preform, and a system determines the withdrawal rate of the powder preform according to the top end shape P; an upper laser and a lower laser of a second laser instrument measure diameters of an upper point and a lower point of a coating layer respectively to further calculate the slope K of the deposition coating layer. An analytical system compares the differences between the actual parameters d1, P1 and K1 and the set parameters d0, P0 and K0 of the deposition powder preform. During the deposition process of the powder preform, a measuring system (a laser diameter measuring instrument), a control system and the analytical system are in closed cycle, the system is in real-time measurement, analysis and adjustment processes, and the deposition process can be controlled through the K value at the initial period when the top end shape of the coating layer deviates from the control mid-value so as to obtain the coating layer with uniform external diameter and improve the quality of the powder preform.

Description

Technical field [0001] The invention relates to a method for preparing a large-size ultra-low water peak optical fiber preform by a gas phase axial method, in particular to a method for manufacturing an optical fiber preform; Background technique [0002] Optical fiber is the basis of modern communication, and optical fiber preform is the main raw material for drawing optical fiber. At present, the preparation method of commercial preform generally adopts a "two-step" manufacturing process, that is, the first step is the preparation of the core rod; the second step, The mandrel is covered with a cladding and formed into a rod; among them, typical mandrel manufacturing processes include: PCVD (plasma chemical vapor deposition) plasma excited chemical vapor deposition, MCVD (modified chemical vapor deposition) improved chemical vapor deposition, OVD ( outside vapor deposition method and VAD (vapor axial deposition) vapor axial deposition method; among them, PCVD and MCVD are collec...

AI Technical Summary

Problems solved by technology

[0011] 1. During the deposition process, the deposition chamber is filled with suspended solid particles, which will cause large background noise in the image acquisition process of the CCD imager, affect the quality of the acquired image, and then reduce the control accuracy;

[0012] 2. There will be a tailing effect during the blowtorch deposition process, that is, a large amount of fluffy loose body will be deposited at the far end of the deposition surface, and the second blowtorch will deposit the cladding layer at the outer end of the deposited core layer. Therefore, the second blowtorch during the deposition process The blowtorch will sinter a large amount of fluffy loose bodies deposited on the far end of the deposition surface of the first torch, resulting in a large deviation between the end face shape of the powder preform and the set shape in the actual deposition process, and the deposition on the far end of the deposition surface of the second torch A large number of fluffy soot bodies are not suitable as the outer diameter control parameter of the powder preform because of their low density;

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