在正交偏振光谱（OPS）微循环成像系统的基础上, 提出了通过改变信号光的偏振态来实现成像深度的选择。 传统的OPS系统利用的是正交线偏振光, 只能获得图像在某一断层的二维信息, 但作者通过控制系统起、 检偏单元椭圆偏振光的椭圆度, 可以在不进行机械扫描的情况下将成像光束聚焦在不同的断层, 从而获得不同深度处的组织信息。 构建的变偏振光谱成像系统将光源发射光谱与红血球吸收光谱相匹配, 可以实现微血管的探测, 且具有较高的信噪比。 对一块含标记物的猪肉脂肪进行实验, 并通过图像处理得到了对比度与信号光偏振态间的定量关系。 实验结果表明: 椭圆度由0°～45°增大, 即从线偏振光向圆偏振光转变的过程中, 对比度逐渐增大, 可探测到的最大深度增大。 最后利用该系统, 对裸鼠耳廓微血管进行了变偏振光谱测量实验, 实验证明了控制偏振态可以实现对血管不同深度的探测, 为微血管断层光谱成像提供了一种新的研究手段。

A continuous depth selectivity is examined by changing the state of polarization of the signal light, based on the orthogonal polarization spectral (OPS) microcirculation imaging system. Unlike the traditional OPS system, which could only rend a two dimensional image of a certain cross-section, the elliptically polarized light controlled by the polarizer unit and the analyzer unit could do the microscopy refocusing without mechanically scanning the sample, as a result, the tissue information at different depths could be obtained. Because the proposed system matches the emission spectrum of the light source with the absorption spectrum of the erythrocyte, it has relatively high signal-to-noise ratio, and could be used to detect microcirculation. Imaging of a pork fat with a target is acquired, and the quantitative relationship between image contrast and the state of polarization is illustrated. The results show that from linearly to circularly polarized illumination, the image contrast gradually increases, and the maximum visible depth also increases. Finally, the auricle vessel of a nude mouse was detected by this polarization-controlled spectral imaging system. Through the experiment the feasibility of depth selectivity was proved. The proposed method provides new insights to microscopy refocusing of microcirculation.