一种提高扫频光学相干层析成像分辨率的延时自动校正算法

An Automatic Delay Correction Algorithm for Improving Imaging Resolution of Swept Source Optical Coherence Tomography System

在扫频光学相干层析(SS-OCT)仪器中,由于光谱标定信号k-clock与OCT信号之间存在不确定的延时,导致光谱标定结果不准确,成像分辨率降低。延时自动校正算法能够准确地自动校正k-clock信号与OCT信号之间的延时。该算法基于提出的平均峰值法和平均半峰全宽(FWHM)法,对OCT信号进行处理分析,分粗调、微调和精调三步对延时点进行自动查找,根据查找结果完成对延时的校正。延时校正后,通过光谱标定得到波数(k)空间均匀分布的OCT信号,可以实现高分辨率图像的重建。实验结果显示,经过自动延时校正,成像分辨率可提高60%,证实了该算法的有效性。

In the swept source optical coherence tomography （SS-OCT） instruments, an unfixed delay between the spectral calibration signal k-clock and the OCT signal makes the result of spectral calibration incorrectly, which reduces the imaging resolution. An automatic delay correction algorithm is proposed to automatically correct the delay between k-clock signal and OCT signal accurately. The algorithm based on the proposed average peak method and average full width at half maximum （FWHM） method, through processing and analyzing the OCT signal, divides into coarse adjustment, fine adjustment and accurate adjustment to search for delay point automatically. According to the search result, the delay time is corrected. After delay correction, high resolution reconstructed image is realized through spectral calibration of OCT signal evenly distributes in the wave-number （k） space. Experimental results show that, the imaging resolution improves 60% by correcting the delay automatically, which proves the effectiveness of the proposed algorithm.