McClain S C, Chipman R A, Hillman L W
Appl Opt. 1992 May 1;31(13):2326-31. doi: 10.1364/AO.31.002326.
We use ray-trace equations for uniaxial birefringent materials to derive third-order estimates for aberrations that are produced in imaging through uniaxial plates and horizontal-vertical (HV) depolarizers. An HV depolarizer is a spatial pseudodepolarizer; it converts a uniform input polarization state into a continuum of spatially varying polarization states in an output beam. An HV depolarizer consists of two birefringent wedges whose crystal axes are crossed at 90 degrees . The interface between the wedges is inclined, which leads to a spatially varying retardance that provides the spatial pseudodepolarization. In HV depolarizers, spherical aberration, astigmatism, and image doubling are the principal aberrations for on-axis objects. Only spherical aberration occurs in isotropic plates, while the presence of birefringent wedges introduces astigmatism and image doubling. It is shown that image separation is proportional tothe magnitude of the retardance variation. Image separation is independent of the thickness, wedge angle, and refractive indices that are used to achieve this variation. A computer program is used to perform an exact birefringent ray trace and produces spot diagrams that confirm the aberration estimates.
我们使用单轴双折射材料的光线追踪方程，来推导通过单轴平板和水平 - 垂直（HV）去偏振器成像时产生的像差的三阶估计值。HV去偏振器是一种空间伪去偏振器；它将均匀的输入偏振态转换为输出光束中一系列空间变化的偏振态。HV去偏振器由两个双折射楔组成，其晶轴相互交叉成90度。楔之间的界面是倾斜的，这导致了空间变化的相位延迟，从而产生了空间伪去偏振。在HV去偏振器中，球差、像散和图像重影是轴上物体的主要像差。在各向同性平板中只出现球差，而双折射楔的存在会引入像散和图像重影。结果表明，图像分离与相位延迟变化的幅度成正比。图像分离与用于实现这种变化的厚度、楔角和折射率无关。使用计算机程序进行精确的双折射光线追踪，并生成光斑图，以证实像差估计。
