扫频OCT系统k域相位数值补偿方法研究

Research on k-domain Phase Compensation Method for Swept OCT System

由于各个镜面的转轴、面型误差和镜面机械旋转抖动等因素引起扫频光源输出光谱的不稳定,使得经过马赫-曾德尔干涉仪产生的等波数取样并不十分理想,导致扫频光学相干层析成像(Optical Coherence Tomography,OCT)系统轴向分辨率与信噪比降低。通过平均波数域(k域)不同成像深度处的原始解缠相位与线性拟合相位的相位差得到补偿数据,实现扫频OCT系统等波数间隔取样不理想的数值补偿,在5 mm成像深度范围轴向分辨率稳定在12.67~16.63μm,接近系统理想分辨率,系统信噪比增大率最大达到7.4%。使用经k域相位数值补偿后的扫频OCT系统进行盖玻片堆和3D打印支架等成像测试,结果表明数值补偿后的成像效果更好。

The unstable output spectra caused by the errors of rotating axis and surface shape of each mirror and the jitter of mirror mechanical rotation make the sampling of equal wavenumber produced by Mach-Zehnder interferometer imperfect, which results in the decrease of the axial resolution and signal-to-noise ratio of the swept source optical coherence tomography(OCT) system, and further decreases with the deepening of the imaging depth. In this paper, the phase difference between the original unwrapping phase and the linear fitting phase at different imaging depths in k domain is used to compensate the imperfect K-clock sampling in OCT system. In the depth range of 5 mm imaging, the axial resolution is stable between 12.67 and 16.63 μm, and the maximum signal-to-noise ratio increase rate is up to 7.4%. The OCT system after k domain phase numerical compensation is used to test the imaging performance of cover glass stack and 3 D printing scaffold, which shows that the imaging effect of numerical compensation is better.