Long focal depth characteristics of the “peacock eye” zone plate

Based on the energy conservation principle and the paraxial ray tracing method,the "peacock eye" zone plates are designed and encoded.The plates are used as the elements with long focal depth,whose two important parameters:the axial intensity distribution and the axial variation of the focused-central-spot size,are simulated and analyzed.At last,the constant central-spot size within a finite focal segment is concluded and the corresponding experimental results are also illustrated.