幅值和相位配准技术及其在光学相干层析血流成像中的应用

频域光学相干层析系统中扫描机构定位精度、 机械抖动及样品移动会造成A扫描信号幅值和相位发生波动, 影响生物组织成像质量. 利用最小灰度差匹配、Lorentzian曲线极值拟合和谱域光程差补偿等方法对A 扫描信号进行幅值配准. 通过对A扫描信号相位分布特征的匹配实现相位差检测与配准. 通过求已配准的A 扫描复信号之差, 消除静态组织对血流成像的影响. 进行了人眼扫描实验, 有效提取了视网膜三维血流图像. 实验结果表明, 提出的幅值及相位配准方法大大减小了系统扫描精度、人眼跳动等因素对生物组织在体成像质量的影响. 快速、精确的相位配准方法也可广泛应用在多普勒OCT、相位显微等与相位分辨有关的光学成像领域. 关键词： 频域光学相干层析 配准 血流成像 相位分布特征

Application of amplitude and phase registration in blood flow imaging using optical coherence tomography

The amplitude and phase fluctuations of A-scans, influenced by the galvanometer positioning accuracy, mechanical jitter, and especially the ovement of the sample, may lead to the distortion and degradation of the tissue structure images and the blood flow images within tissue beds in frequency domain optical coherence tomography. The amplitude registration method for A-scans is proposed based on the minimum intensity difference matching criterion, Lorentzian curve fitting method, and compensation of the optical path difference in interference spectrum. The phase differences between A-scans are detected and registered by matching of phase distribution characteristics of A-scans. After the amplitude and phase registration, the complex signal differences between two A-scans are calculated to eliminate the effect of the static tissue on the blood flow imaging. The eye scanning experiments were performed and three-dimensional blood flow images of retina were acquired. Experiment results indicate that the effect of system scanning accuracy and tissue movement on the image quality can be effectively eliminated by the proposed amplitude and phase registration method. The fast and accurate phase registration method can also be used in Doppler OCT, phase microscope, and other phase related applications.
Keywords： frequency domain optical coherence tomography registration blood flow imaging phase distribution characteristics