光学相干层析系统色散的在线测量及补偿_孟卓

第22卷第2期2011年2月

光电子#激光

Journal of Optoelectronics#Laser V o l.22N o.2F eb.2011

光学相干层析系统色散的在线测量及补偿

孟卓1*,梁雨1,姚晓天1,姚晖2,刘铁根1,万木森1

(1.天津大学精密仪器与光电子工程学院,光电信息技术科学教育部重点实验室,光偏振研究中心,天津300072;2.天津市口腔医院暨南开大学附属口腔医院实验研究中心,天津300041)

摘要:针对光学相干层析(OCT)系统中迈克尔逊干涉仪两臂色散不匹配导致纵向分辨率的降低,提出了一种基于频域干涉及非线性曲线拟合的方法对干涉仪两臂色散差进行在线测量,根据测量结果在干涉仪一臂中加入非零色散位移光纤(NZDSF)对色散差进行补偿。实验结果表明,经过色散补偿后系统的纵向分辨率与理论值相符合,离体牙齿OCT图像的质量得到了明显改善。

关键词:光学相干层析(OCT);色散测量;色散补偿;非零色散位移光纤(NZDSF)

中图分类号:TN247;R318.51文献标识码:A文章编号:1005-0086(2011)02-0256-05

In-line m easurem ent and com pensation for dispe rsion in O C T sys-tem

MENG Zhuo1*,LIANG Yu1,YAO Xiao-tian1,YAO Hui2,LIU Tie-gen1,W AN Mu-sen1 (1.Key Laborator y of Opto-electronics Information and Technical Science,EM C,Optical Polarization Research Cen-ter,College of Precision Instrument and Opto-electronics Engineering,T ianjin University,T ianjin300072,China; 2.Ex per i mental Research Center,T ianjin Stomatological Hospital,Affiliated Dental College of Nankai U niversity, T ianjin300041,China)

Ab st ract:It is known t hat if the dispersion of one channel of the Michelson interferometer in the opt ic al coherence tomography(OCT)system does not match the other,the interferogram envelope will be broadened so that the axial resolution will be dec reased.The influenc e of unbalanced dispe rsion betwee n the two channels of michelson interferometer,on the axial resolution in the OCT system is analyzed and an on-line method based on the spectral interfe renc e pattern and nonlinear curve fitting is present e d to measure the dispersion difference between two channels of the int e rferometer.Acc ording to the measured results,a non zero dispersion shifted fibe r(NZDSF)is used in one channel to compensate the dispersion of the interferometer.T he experimental result s indicate that the axial resolut ion after the dispersion compensation agrees with t he theoretical value,and the quality of t he OCT image of an extrac ted human tooth is improved signific antly.

Ke y wor ds:optical coherence tomography(OCT);dispe rsion measurement;dispersion compensation; non ze ro dispersion shifted fiber(NZDSF)

1引言

光学相干层析(OCT)是一种迅速发展的生物组织成像技术,它具有高分辨率、无损伤和实时性等优点,已经广泛应用于眼科、皮肤、心脑血管疾病、肠胃病和牙科等医学诊断领域[1~7]。OCT系统的纵向分辨率取决于所使用的光源的相干长度[8],其与光源的带宽成反比,目前已能获得L m量级的纵向分辨率[9]。采用光纤器件构成的OCT系统,具有体积小、集成度高和稳定性好等优点,极大地推进了OCT技术的发展。然而,若全光纤OCT系统中迈克尔逊干涉仪两臂光纤色散不匹配,会使得光源的相干长度变大,干涉信号包络的展宽,进而导致系统纵向分辨率的降低[10]。为了解决这一问题,可以通过使用数值补偿的软件方法[9]或在干涉仪一臂中加入色散介质、快速扫描光学延迟线等硬件方法[11,12]来实现。这些色散补偿方法主要通过在干涉仪中引入一定量的附加色散以达到匹配两臂色散的目的,因此必须对迈克尔逊干涉仪两臂色散差进

*E-mail:tjictom@

收稿日期:2010-03-18修订日期:2010-09-28

基金项目:国家/9730计划资助项目(2010CB327802);国家自然科学基金资助项目(30770597);中国博士后科学基金资助项目(20100470782)