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提出了一种基于扫频光学相干层析术的散斑方差(SV)和多普勒算法结合的方法来提取人体皮肤毛细血管的血流信号。这种方法利用了SV算法获取血流信号强度和多普勒算法获取相位信息的优势。SV算法对两幅结构图同一位置的强度进行方差运算。多普勒算法可以通过测量相邻A扫之间的相位变化来获取多普勒频移,进而获取血流流速信息,但这种方法中扫频光源的相位和采样信号随时间存在漂移,导致触发信号和采集卡模数转换之间的延迟时间在一个取样时钟周期中变化。为了校正这部分相位变化,实验系统中采用双参考镜,通过校正两参考镜相邻A扫之间的相位变化来对相应血流部分进行相位校正。进行了样本模拟实验和人体皮肤成像实验,SV算法获取血流强度和经标准平面镜校正的多普勒频移来获取血流方向,综合运用两种方法得到具有方向信息的血流强度图。
A method combining speckle variance (SV) and Doppler algorithm based on swept-frequency optical coherence tomography was proposed to extract blood flow signals of human skin capillaries. This method takes advantage of the SV algorithm to obtain the signal strength of the blood flow and the Doppler algorithm to obtain the phase information. SV algorithm performs the variance calculation on the intensity of the same position of two structure diagrams. The Doppler algorithm can obtain the Doppler frequency shift by measuring the phase change between adjacent A-scans, and then obtain the blood flow velocity information. However, the phase of the frequency-swept light source and the sampled signal in this method drift over time, resulting in The delay between the trigger signal and the acquisition card analog-to-digital conversion changes during one sample clock cycle. In order to correct this part of the phase change, a double reference mirror is used in the experimental system, and the corresponding blood flow part is phase-corrected by correcting the phase change between the adjacent A-scan of the two reference mirrors. Experiments on samples and human skin were carried out. SV algorithm was used to obtain the blood flow intensity and the Doppler shift corrected by the standard plane mirror to obtain the blood flow direction. The two methods were used to obtain the blood flow intensity map with direction information.