| Photon Sieves(PS) is a novel Diffractive Optical Element(DOE) can be used to focusing and imaging X rays which can't done by lens and other focusing optical element made of glass. Introduced the PS focusing and imaging principle; calculated numeric results of diffraction field in space when light impinging on X-ray PS(λ=4.5nm)with plane wave angular spectrum method. Gave the axial and radial intensity distribution pattern, analyzed the effect of background light to the focus spot. Studied the Full Width at Half -Maximum(FWHM), Depth Of Focus(DOF) and Strehl efficiency of the focus spot. The results hints that compared with Fresnel Zone Plate (FZP), photon sieves provide with the advantages of higher resolution suppress secondary maxima and improve image contrast.Detailed introduced the design process of PS. Designed FZP, unapodized PS and apodized PS based on theoretical analyses and computer simulation, compared their focusing and imaging quality simulated by MATLAB. Finally, tested their focus spots by experiment, the laser wavelength is 532nm. The experiment results indicate the PS has smaller focus spot and higher contrast compared with FZP. |
