径向双折射滤波器的超分辨性能研究

Research on Superresolution of Radial Birefringent Filter

超分辨技术因其可以超越经典的衍射极限而为人们所熟知,并且在光存储和共焦扫描成像系统中有着广泛的应用。把由两个偏振器和一个圆对称的双折射元件组成的径向双折射滤波器引入超分辨技术,借助琼斯算法推导出其光瞳函数的表达式。由分析得出通过改变径向双折射滤波器中偏振器的偏振方向和双折射元件的主轴之间的夹角,即可实现光学系统的横向超分辨或轴向超分辨。同时对评价该器件超分辨性能的参量第一零点比、斯特尔比和旁瓣强度抑制比做了详细的讨论。该滤波器用于超分辨技术的优点在于其制作不涉及相位的变化而比较简单,且费用比较低。缺点是旁瓣能量过高,但可以通过采用共焦系统来抑制。

Superresolution technique is well known for the ability of compressing the central diffraction spot beyond the classic diffraction limit, and it has a wide application in the optical storage and the confocal imaging systems. The radial birefringent filter which consists of two parallel polarizers and a rotationally symmetric birefringent element is introduced into the superresolution technology, and with Jones calculus the pupil function of it is deduced. It is shown that with such filter transverse or axial Superresolution can be realized just by changing the angle between the polarizers and the radial birefringent element. At the same time, the superresolution parameters G, Strehl ratio S and the influence of side-lobes are discussed. Advantages of such filter are that it is relatively simple to construct as it requires no phase changes with low cost. Disadvantage is its high strength of the side-lobes, but that can be suppressed by applying confocal system.