We detail the design and characterization of a terahertz range achromaticquarter-wave plate based on a stack of aligned variable thickness birefringentsapphire discs. The disc thicknesses and relative rotations of the discs aredetermined through a basin-hopping Monte Carlo thermal annealing routine. Thebasin-hopping scheme allows an improved refinement of the required thicknessesand rotations to give a predicted phase error from the ideal $pi/2$ of only$0.5 %$, which is a factor of approximately 6 better than previous efforts.Moreover, the large contrast between extraordinary and ordinary axes ofsapphire allow us to greatly decrease the overall optical path length of ourwave plate design by approximately a factor of 10 over similar designs based onquartz discs. However, this very same contrast requires very precise tolerancesin the milled thicknesses of the discs and their assembly. We detail a methodto compensate for differences in the thickness from their calculated idealvalues. We have constructed one of our designs and found it similar inperformance to other configurations, but with our much more compact geometry.
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机译：我们将基于一堆对齐的可变厚度二射晶圆盘的叠层设计和鉴定了太赫兹范围抗皱型陀螺板。通过盆地跳跃蒙特卡罗热退火常规，盘的厚度和相对旋转通过盆地跳跃。跳跃方案允许改进的精细化改进所需的厚度和旋转，从理想的$ pi / 2 $给出预测的相位误差仅为0.5美元，这比以前的努力更好地为大约6。非凡和普通轴之间的大对比度使我们能够大大降低我们的Wave板设计的整体光路长度大约在基于类似的设计上的overz圆盘上的相似设计。然而，这种相同的对比度需要非常精确的耐受性的铣削厚度和它们的组件。我们详细介绍了一种方法来补偿厚度的差异从其计算的eadeValues。我们已经构建了我们的设计之一，发现它与其他配置相似，但我们更紧凑的几何形状。
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