光纤倾斜耦合角度的快速精密图像测量

光纤与光芯片的上表面耦合的倾斜角度是影响光耦合效率的关键因素之一，针对传统角规测量法效率低、精度差和不稳定等问题，采用坐标系重构方法和图像处理技术实现了对光纤倾斜耦合角度的快速精密测量。首先，在常规图像角度测量的基础上引入棋盘靶标进行坐标系重构，降低了CCD在光学放大获取微小光纤的图像信息时光轴轻微转动引起的误差。然后，为了在降低噪声影响的同时保障光纤直线特征的检测精度，对比了Hough变换和图像细化两种提取光纤直线参数的算法，结合直线元素在投影面的三角关系获得了光纤倾斜角度。实验结果表明:基于Hough变换的直线提取算法误差在0.1，平均运算时间为0.370 s，实现了对微小尺寸下光纤倾斜耦合角度快速精确地测量。

Rapid and precise image measurement of oblique angle of the coupling fiber

The oblique angle of the fiber coupling to the upper surface of the optical chip, is one of the key factors affecting the optical coupling efficiency. Contrary to the low efficiency, poor precision and instability of the traditional angle measurement methods, the coordinate system re-establishment method combined the image processing technology were adopted to realize the rapid and precise measurement of the oblique angles. Firstly, based on conventional image angle measurement method, a targeted checkerboard was introduced to calibrate coordinate system, thus reducing the errors caused by slight rotations of the optical axis, which would happen at the time that the CCD optical amplification system acquiring the image information of the tiny optical fiber. Then to reduce the influence of noise while ensuring the detection accuracy of the linear characteristics of the fiber, Hough transform method and image thinning method, which were two classic methods to extract the linear parameters of the fiber, were compared. Combining the triangular relationship of the linear elements on the projection surface, the oblique angle of the coupling fiber was finally obtained. The experimental results show that the line extraction algorithm based on Hough transform can measure oblique angle of the coupling fiber optic under small size with higher accuracy and speed, the error is about 0.1 and the average operation time is 0.370 seconds.