基于3D定位的光纤棒内部缺陷检测方法

Internal defect detection of optical fiber preform based on 3D location

为检测和定位光纤预制棒的内部缺陷并提高精度,提出一种光线追踪实现3D精确定位的线激光旋转扫描检测方法。利用光散射原理和暗场成像技术,成像设备采集光纤棒每个旋转角纵截面上缺陷的散射光;原始图像经过图像预处理和图像分割获取缺陷的二维信息;基于折射定律和光线追踪建立缺陷的精确定位模型,消除光纤棒表面折射带来的成像位置偏差;最后经过坐标转换、三维建模和三维连通域提取实现缺陷在光纤棒内部的3D定位。实验结果表明:120 W像素的工业相机在旋转角步长为0.9°的条件下,对大尺寸的光纤棒内部缺陷检测轴向定位精度为0.28 mm,径向定位精度为1.05 mm,可实现准确、自动化地检测和定位光纤棒的内部缺陷,为光纤棒的质检和指导光纤拉丝提供重要依据。

A Line-laser rotational scanning detection method for 3D precise positioning by ray tracing to detect and locate the internal defects of optical fibre preform more accurately.Based on the law of light scattering and darkfield imaging technology,the camera collects the scattered light at the preform internal defects at each angle.The obtained images are processed and segmented to obtain the 2d information of the defects.Then,based on the system’s analysis and ray tracing method,the defect position correction model is established.Finally,the 3D location of the optical fibre preform defect is realised by coordinate transformation,3D modelling,and 3D connected domain extraction.The experimental results show that the axial accuracy and radial accuracy of the system for detecting the internal defects of large-size fibre prefabricated rod is 0.28 mm and 1.05 mm respectively in the condition that camera has 120 W pixels and the step of the rotating platform is 0.9°.The system can accurately and automatically detect and locate the optical fibre preform’s internal defects,which provides an essential basis for quality inspection of optical fibre preform and guiding fibre drawing.