Measurement of optical fiber geometry with arbitrary ellipse curve fitting

Li Yiming; Zheng Gang; Tu Jiankun; Xiang Huazhong; Jiang Bin; Ge Bin

doi:10.12086/oee.2019.180319

Article navigation > Opto-Electronic Engineering > 2019 Vol. 46 > No. 5 > 180319

Next Article Previous Article

Li Yiming, Zheng Gang, Tu Jiankun, et al. Measurement of optical fiber geometry with arbitrary ellipse curve fitting[J]. Opto-Electronic Engineering, 2019, 46(5): 180319. doi: 10.12086/oee.2019.180319

Citation:

Li Yiming, Zheng Gang, Tu Jiankun, et al. Measurement of optical fiber geometry with arbitrary ellipse curve fitting[J]. Opto-Electronic Engineering, 2019, 46(5): 180319. doi: 10.12086/oee.2019.180319

Measurement of optical fiber geometry with arbitrary ellipse curve fitting

1.
Interventional Medical Device Engineering Research Center, University of Shanghai for Science and Technology, Shanghai 200093, China
2.
Shanghai Cable Research Institute, Shanghai 200093, China

Fund Project: Supported by National Natural Science Foundation for Young Scientists of China (61605114)

More Information

Corresponding author: Zheng Gang, E-mail:gangzheng@usst.edu.cn

Received Date 11 June 2018

Revised Date 06 August 2018

Published Date 25 May 2019

Abstract

Abstract

The fiber geometry of communication fibers and medical fibers are always standards to evaluate the quality of optical fibers. The measurement of fiber geometry with gray scale method is one of the commonly used measurement methods. It is also the proposed method in the national standard GB15972.20-2008. In this method, the fiber geometry is obtained by fitting the elliptical curve and fitting the circular curve in two steps, but the center of the two curves may not be coincided. Thus, there is a defect in the measurement principle in the method. The measurement of fiber geometry with gray scale method has a high requirement for cutting effects and lighting conditions. When measurement conditions change, it often leads to the instability of the measured data and brings errors. In this paper, we use the arbitrary elliptical function (non-standard ellipse) which is more suitable for the fiber end face, and only use this function fitting method to get the fiber geometry to fundamentally eliminate the principle defect caused by the inconsistent center fitting between the circle fitting and the ellipse fitting. At the same time, the requirement of measurement condition is reduced, because the specific value of image distribution grayscale is not needed when calculating each parameter. Experiments show that this method can effectively improve the stability and consistency of measurement results.
- optical fiber geometry /
- gray scale method /
- ellipse curve fitting

FullText(HTML)

References

[1]	中华人民共和国国家质量监督检验检疫总局, 中国国家标准化管理委员会.光纤试验方法规范第20部分: 尺寸参数的测量方法和试验程序光纤几何参数: GB 15972.20–2008[S].北京: 中国标准出版社, 2008. Google Scholar General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China. Specifications for optical fibre test methods-part 20: measurement methods and test procedures for dimensions- fiber geometry: GB 15972.20–2008[S]. Beijing: Standards Press of China, 2008. Google Scholar
[2]	陈磊, 陈进榜, 陆润华.光纤几何参数的自动检测仪[J].光学学报, 2001, 21(10): 1245–1248. doi: 10.3321/j.issn:0253-2239.2001.10.021 CrossRef Google Scholar Chen L, Chen J B, Lu R H. Automatic measurement of optical fiber geometric parameters[J]. Acta Optica Sinica, 2001, 21(10): 1245–1248. doi: 10.3321/j.issn:0253-2239.2001.10.021 CrossRef Google Scholar
[3]	殷爱娥, 姜仲玄, 张一龙.光纤折射率剖面的折射近场法测量的研究[J].光学学报, 1989, 9(2): 181–185. doi: 10.3321/j.issn:0253-2239.1989.02.014 CrossRef Google Scholar Yin A E, Jiang Z X, Zhang Y L. Refracted near-field technique for the measurement of optical fiber refractive index profiles[J]. Acta Optica Sinica, 1989, 9(2): 181–185. doi: 10.3321/j.issn:0253-2239.1989.02.014 CrossRef Google Scholar
[4]	高迎春.基于折射近场法测量光纤折射率分布的仿真研究[D].哈尔滨: 哈尔滨工程大学, 2012. Google Scholar Gao Y C. Simulation of measuring the optical fiber refractive index profiles by refraction near-field method[D]. Harbin: Harbin Engineering University, 2012. Google Scholar
[5]	孙会刚, 储九荣, 钟力生, 等.塑料光纤折射率分布的测量方法[J].光纤与电缆及其应用技术, 2001(4): 12–16. doi: 10.3969/j.issn.1006-1908.2001.04.004 CrossRef Google Scholar Sun H G, Chu J R, Zhong L S, et al. Measurement of refractive-index profile of plastic optical fibers[J]. Optical Fiber & Electric Cable, 2001(4): 12–16. doi: 10.3969/j.issn.1006-1908.2001.04.004 CrossRef Google Scholar
[6]	贾宏志, 李育林, 忽满利.光纤光栅的制作方法[J].激光技术, 2001, 25(1): 23–26. doi: 10.3969/j.issn.1001-3806.2001.01.001 CrossRef Google Scholar Jia H Z, Li Y L, Hu M L. Fabrication methods of fiber gratings[J]. Laser Technology, 2001, 25(1): 23–26. doi: 10.3969/j.issn.1001-3806.2001.01.001 CrossRef Google Scholar
[7]	武志宏.基于CCD和图像处理技术的六角光纤几何尺寸测量系统的研究[D].太原: 太原理工大学, 2006. Google Scholar Wu Z H. The research about measurement system of six-angle fiber geometrical dimension on the basis of CCD and image processing[D]. Taiyuan: Taiyuan University of Technology, 2006. Google Scholar
[8]	马利东.光子晶体光纤有效模面积测量技术的研究[D].秦皇岛: 燕山大学, 2016. Google Scholar Ma L D. Research on effective mode area measurement of photonic crystal fiber[D]. Qinhuangdao: Yanshan University, 2016. Google Scholar
[9]	Hameed M F O, Obayya S S A. Modal analysis of a novel soft glass photonic crystal fiber with liquid crystal core[J]. Journal of Lightwave Technology, 2012, 30(1): 96–102. doi: 10.1109/JLT.2011.2175436 CrossRef Google Scholar
[10]	Rosa L, Coscelli E, Poli F, et al. Thermal modeling of gain competition in Yb-doped large-mode-area photonic-crystal fiber amplifier[J]. Optics Express, 2015, 23(14): 18638–18644. doi: 10.1364/OE.23.018638 CrossRef Google Scholar
[11]	杨远.基于机器视觉的光纤几何参数检测研究[D].哈尔滨: 哈尔滨工程大学, 2011. Google Scholar Yang Y. Research on detecting optical fiber geometric parameter based on machine vision[D]. Harbin: Harbin Engineering University, 2011. Google Scholar
[12]	凌凤彩, 康牧, 林晓.改进的Canny边缘检测算法[J].计算机科学, 2016, 43(8): 309–312. doi: 10.11896/j.issn.1002-137X.2016.8.063 CrossRef Google Scholar Ling F C, Kang M, Lin X. Improved Canny edge detection algorithm[J]. Computer Science, 2016, 43(8): 309–312. doi: 10.11896/j.issn.1002-137X.2016.8.063 CrossRef Google Scholar
[13]	郭萌, 胡辽林, 赵江涛.基于Kirsch和Canny算子的陶瓷碗表面缺陷检测方法[J].光学学报, 2016, 36(9): 0904001. doi: 10.3788/aos201636.0904001 CrossRef Google Scholar Guo M, Hu L L, Zhao J T. Surface defect detection method of ceramic bowl based on Kirsch and Canny operator[J]. Acta Optica Sinica, 2016, 36(9): 0904001. doi: 10.3788/aos201636.0904001 CrossRef Google Scholar
[14]	王文豪, 姜明新, 赵文东.基于Canny算子改进的边缘检测算法[J].中国科技论文, 2017, 12(8): 910–915. doi: 10.3969/j.issn.2095-2783.2017.08.013 CrossRef Google Scholar Wang W H, Jiang M X, Zhao W D. Edge detection algorithm based on improved Canny operator[J]. China Sciencepaper, 2017, 12(8): 910–915. doi: 10.3969/j.issn.2095-2783.2017.08.013 CrossRef Google Scholar
[15]	王万国, 王仕荣, 徐正飞, 等.基于边界的最小二乘椭圆拟合改进算法[J].计算机技术与发展, 2013, 23(4): 67–70. doi: 10.3969/j.issn.1673-629X.2013.04.016 CrossRef Google Scholar Wang W G, Wang S R, Xu Z F, et al. Optimal ellipse fitting algorithm of least square principle based on boundary[J]. Computer Technology and Development, 2013, 23(4): 67–70. doi: 10.3969/j.issn.1673-629X.2013.04.016 CrossRef Google Scholar
[16]	熊风光, 李希, 韩燮.基于整体最小二乘的椭圆拟合方法[J].微电子学与计算机, 2017, 34(1): 102–105. Google Scholar Xiong F G, Li X, Han X. A method of ellipse fitting based on total least squares[J]. Microelectronics & Computer, 2017, 34(1): 102–105. Google Scholar
[17]	曹俊丽, 李居峰.基于莱特准则的椭圆拟合优化算法[J].计算机应用, 2017, 37(1): 273–277. doi: 10.11772/j.issn.1001-9081.2017.01.0273 CrossRef Google Scholar Cao J L, Li J F. Improved ellipse fitting algorithm based on Letts criterion[J]. Journal of Computer Applications, 2017, 37(1): 273–277. doi: 10.11772/j.issn.1001-9081.2017.01.0273 CrossRef Google Scholar
[18]	Gander W, Golub G H, Strebel R. Least–squares fitting of circles and ellipses[J]. BIT Numerical Mathematics, 1994, 34(4): 558–578. doi: 10.1007/BF01934268 CrossRef Google Scholar
[19]	Mitchell D R G, Van den Berg J A. Development of an ellipse fitting method with which to analyse selected area electron diffraction patterns[J]. Ultramicroscopy, 2016, 160: 140–145. doi: 10.1016/j.ultramic.2015.10.009 CrossRef Google Scholar
[20]	何晨程, 杨婧, 宋海燕, 等.切割刀老化对单模光纤几何尺寸检测结果的影响[J].现代传输, 2016(1): 56–61. doi: 10.3969/j.issn.1673-5137.2016.01.001 CrossRef Google Scholar He C C, Yang J, Song H Y, et al. Effect of cutting tool aging on the geometric size measurement of single mode fiber[J]. Modern Transmission, 2016(1): 56–61. doi: 10.3969/j.issn.1673-5137.2016.01.001 CrossRef Google Scholar
[21]	刘为, 唐春晖, 马秀梅, 等.缺陷光纤端面几何参数的测量[J].光通信研究, 2013, 39(6): 35–38. doi: 10.3969/j.issn.1005-8788.2013.06.011 CrossRef Google Scholar Liu W, Tang C H, Ma X M, et al. Measurement of geometric parameters of defective fiber ends[J]. Study on Optical Communications, 2013, 39(6): 35–38. doi: 10.3969/j.issn.1005-8788.2013.06.011 CrossRef Google Scholar

Overview

Overview

Overview: The fiber geometry of communication fibers and medical fibers are always important parameters to evaluate the quality of optical fibers. The fiber geometry mainly includes the diameter and ovality of claddings and cores, and the concentricity error of claddings and cores. The measurement of fiber geometry with gray scale method is one of the commonly used measurement methods proposed in the national standard GB15972.20-2008. In the gray scale method, the fiber geometry is obtained by two-step fittings that are the fitting of circular curve and the fitting of ellipse curve. However, the geometric centers of the two fitting curves may not necessarily coincide, causing the measurement inaccuracy of fiber geometry. Obviously, there is a defect of the measurement principle in the method. The measurement of fiber geometry with gray scale method has a high requirement for cutting effects and lighting conditions. When measurement conditions change, it often leads to the instability of the measured data and brings errors. This paper proposes a method for obtaining the optical fiber geometry with fitting the edge of optical fiber in an arbitrary ellipse curve (non-standard ellipse) which more coincide the real optical fiber end face.
The method is mainly divided into three steps: image preprocessing, edge extraction and ellipse curves fitting. The first step, image preprocessing, is to eliminate some of the noise errors in the image by median filtering the image, in order to make the subsequent edge extraction better. The second step, edge extraction, is to use the Canny operator to extract the image of the optical fiber end face. At this time, there are still some noise signals and false edges at the edge of the optical fiber. The third step, ellipse curves fitting, is to fit the edge data points with the arbitrary ellipse, and to set an appropriate threshold value at the edge of the fitting ellipse curve, then is to remove the data points beyond the threshold value as error data points. All optical fiber geometry can be calculated by arbitrary ellipse curve in one-step fitting, so eliminating the measurement error caused by the center inconsistency between the circle curve fitting and the ellipse curve fitting. At the same time, because the specific value of the image distribution gray scale is not required when calculating each parameter, the edge data of the optical fiber is used for fitting, thereby the measurement condition is effectively reduced. Taking fiber core data as an example, the data of diameter and ovality measured by the standard instrument are 8.420 μm and 0.670%, respectively. When cutting effect of fiber end face or lighting condition is poor, the instrument data become 9.436 μm and 2.016%, while the data measured in this paper are 8.804 μm and 0.553%, respectively. Experiment results show that the method can significantly improve the accuracy and precision of the measurement results of instruments.