设计了利用计算全息图(CGH)作为零位补偿器来检测三次位相板的光学系统,最重要的两个理论问题是三次位相在空间传播过程中产生的波像差的具体形式和经过CGH衍射后衍射级次的分离。本文推导了三次位相在传播过程中产生高阶像差的理论公式,并由公式得出高阶项随着传播距离的增大而增大的结论。讨论了检测光波经过CGH衍射后衍射级次分离的理论过程。设计了一个用CGH检测三次位相板的系统作为例证,通过在CGH位相方程中引入高阶项四次项和五次项,使得残余波像差从原来的0.75 λ降至0.007 λ。实验得到的传播过程中的波像差及衍射级次的分离,都与理论推导相吻合。

In the design of cubic phase plate testing system by taking Computer Generated Hologram(CGH) as a null lens,two very important principles are the wavefront aberration of cubic phase in propagation and the separation of diffraction orders.The cubic phase introduced higher order aberration in propagates was presented,and an expression for the aberration of cubic phase in propagating was deduced in detail.From the expression,it was shown that the high order aberration increases as the propagation distance l increase.The theoretical foundation for the diffraction order separation of testing wavefront diffracted by the CGH was discussed.To prove the theories,a cubic phase plate testing system was designed for an example.By introducing the 4th and the 5th order items,the wavefront aberration reduced from 0.7 λ to 0.007 λ.The results coincide with the theoretical formula well.