Zhou Yuan, Fan Shixun, Chen Yin, Zhou Xiaoxia, Liu Guangcan
Appl Opt. 2017 Aug 1;56(22):6079-6086. doi: 10.1364/AO.56.006079.
Limitations of beam steering in Risley prisms, induced by total internal reflection, are investigated for the four typical configurations. The incident angles at the exit surfaces of double prisms are calculated by nonparaxial ray tracing and compared with the critical angle. On this basis, the limitations of the opening angle, relative orientation of the prisms, and ray deviation power of the system are derived. It is shown that the ray deviation power reaches its extreme value when the opening angles increase to a certain limit value for a given prism material. As the opening angles exceed the limit value, the prisms' relative orientation is limited. With the increase in refractive index, the limit value of opening angles decreases, while the extreme value of deviation power increases. In comparison to a 21-12, 12-12 configuration, a 21-21, 12-21 configuration has a larger limit value of opening angles and also a larger extreme value (90°) of deviation power, so that it leaves a wider margin for the design of wide-angle beam steering system. The research can afford guidance for prism material and geometry choices in the design of a wide-angle Risley-prism-based beam steering system.
研究了全内反射引起的里斯利棱镜光束转向在四种典型配置下的局限性。通过非傍轴光线追迹计算双棱镜出射面的入射角，并与临界角进行比较。在此基础上，推导了系统的张角、棱镜相对取向和光线偏折能力的局限性。结果表明，对于给定的棱镜材料，当张角增大到一定极限值时，光线偏折能力达到极值。当张角超过极限值时，棱镜的相对取向受到限制。随着折射率的增加，张角的极限值减小，而偏折能力的极值增大。与21-12、12-12配置相比，21-21、12-21配置具有更大的张角极限值和更大的偏折能力极值（90°），从而为广角光束转向系统的设计留出更宽的余量。该研究可为基于广角里斯利棱镜的光束转向系统设计中的棱镜材料和几何形状选择提供指导。
