A device and method for online measurement of the diameter and bow of an optical fiber preform

Abstract

The invention provides a device and method for on-line detection of the diameter and bow of an optical fiber preform. The device includes a measurement base, a protective cover, a cylindrical glass cover, a detection unit, and the like. This test method is based on the heat radiation heat transfer law between the gray body and the black body, by detecting the mid-far infrared band radiated by the optical fiber preform during deposition, melting or stretching (pure silica has Intense radiation, electromagnetic radiation with an emissivity rate above 0.95 (the radiation of the liner or preform enters the detection array through the glass cover), can obtain the bow and diameter information of the preform. The device of the present invention has the advantages of simple structure, low cost (directly use the radiation characteristics of the preform itself for measurement, no additional light source is needed), high precision (the radiation characteristics of glass are very strong and obvious), and strong adaptability (can be used in different temperature environment and liners or preforms of different thicknesses). In addition, the device and method can simultaneously measure the diameter and bow of the preform rod online, which is convenient for guiding production.

Description

technical field [0001] The invention belongs to the field of measurement of optical fiber preforms, and more particularly relates to an on-line measurement device and method for the diameter and bow of optical fiber preforms. Background technique [0002] Monitoring the diameter and bow of the liner (or preform) during the preparation of the optical fiber preform is essential to the preparation process of the preform, which is beneficial to the adjustment of process parameters. At present, there are mainly two types of devices for online measurement of preform diameter: one is composed of a detection laser light source, a detection window assembly, and a detector. The detector can calculate the diameter of the liner by detecting the distribution of the laser beam. The device is generally ring-shaped and suitable for use with a graphite furnace for deposition or stretching. The accuracy is relatively accurate. However, due to the high temperature during use and the need to S...

AI Technical Summary

Problems solved by technology

At present, there are mainly two types of devices for online measurement of preform diameter: one is composed of a detection laser light source, a detection window assembly, and a detector. The detector can calculate the diameter of the liner by detecting the distribution of the laser beam. The device is generally ring-shaped and suitable for use with a graphite furnace for deposition or stretching. The accuracy is relatively accurate. However, due to the high temperature during use and the need to Specific laser light sources and detectors lead to complex and expensive devices, which seriously restricts the application of caliper devices in the field of optical fiber preform preparation; the other is image recognition applied in the visible and near-infrared bands (1-3μm) The principle of the equipment is to fit the diameter of the liner by capturing the outline of the liner during the deposition process. The main problem with this device is that the light in the visible and near-infrared bands is easily affected by the outside world during the deposition process. The measurement accuracy is extremely poor, and the test device is located above the flame, resulting in changes in the refractive index of the upper air after heating, which affects the measurement accuracy

In addition, there is no online bow measurement of optical fiber preform, and the process parameters in the deposition process directly determine the bow of the preform

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