偏振频域OCT系统光谱错位分析及光谱校准

Wavelength Misalignment Analysis and Spectral Calibration for Fourier Domain Polarization-Sensitive Optical Coherence Tomography

偏振频域光学相干层析成像(FD-PS-OCT)可以通过测量样品的偏振特性实现某些疾病的早期诊断。偏振参数的测量精度关系到疾病诊断的准确性。在FD-PS-OCT中,正交的两路干涉信号即使仅存在很小的光谱错位,也可能导致偏振参数计算结果产生较大的误差。光谱校准是提高偏振参数测量精度的前提,而在进行光谱校准之前,有必要明确光谱错位对偏振参数计算精度的影响。通过理论分析和仿真计算,深入分析了光谱错位与偏振参数计算误差之间的关系。在此基础上,提出了一种光谱校准方法,该方法通过判断已知样品延迟量和快轴方位角的误差大小来实现光谱缩放和平移的校准。最后进行了波片测量实验,验证了该方法的有效性,证明了误差分析的正确性。

Fourier domain polarization-sensitive optical coherence tomography（FD-PS-OCT）can measure the polarization properties of a sample to provide early diagnosis for some diseases.The accurate diagnosis is required to measure the polarization parameters in a high accuracy.However,the accuracy is greatly affected by wavelength misalignment.Even a slight wavelength mismatch in FD-PS-OCT will result in nonnegligible polarization artifacts.So an accurate wavelength assignment is necessary.In order to decrease the polarization error and improve the accuracy of spectral calibration,the effect of the wavelength misalignment on the polarization parameters calculation should be clear.An analysis is performed on the relationship between the wavenumber misalignment and the calculated error in theory and simulation.Based on the error analysis,a spectral calibration method is proposed.The method achieves the wavelength alignment through evaluating the retardation and fast axis orientation errors.The wave plate experiments show the good performance of the method and the reasonability of the error analysis.