我们研制了一种基于光纤的位相分辨偏振灵敏光学相干层析成像系统.该系统中的偏振状态控制设置在参考臂而非光源臂上,因而使得光抵达样品的传输效率大大提高.鉴于光源的部分偏振性,入射于样品上的光含有任意偏振状态的分量,通过对参考光偏振状态的调制,就可相干地提取对应于入射光四种正交偏振状态并经样品后向散射的光信号.基于斯托克斯矢量夹角在无损光纤系统传输的变换不变性,我们能利用测量臂中光信号的斯托克斯参数来确定双折射样品深度分辨的位相延迟信息.利用所研制的偏振灵敏光学相干层析成像系统,不仅确认了韧带和软骨的双折射性质,而且定量分析了不同条件下韧带的双折射变化.研究结果表明:韧带松弛可使其双折射特性明显减弱,而韧带经拉伸后,其双折射特性的变化却不明显.

A fiberdesigned phase resolved polarizationsensitive optical coherence tomography (PSOCT) system was developed. The polarization modulator in this system was introduced in the reference arm rather than the source arm, providing an increased power delivered from light source to sample. As the source is only partially polarized, the light incident on the sample has components of any polarization states. Modulating the polarization states of light at the reference arm, backscattered light that originates from incident light upon sample at four orthogonal polarization states was coherently picked out. Based on angle preservation of Stokes vectors in the PSOCT system, Stokes parameters of backscattered light measured at the detection arm were used to determine the phase retardation of birefringence samples as a function of depth. Using this PSOCT system, birefringence of ligament and cartilage are confirmed. Investigation on birefringence alternation of ligament under different conditions is conducted. Ligament relaxation induces significant lose of ......