Research On Design Method Of Large Photon Sieve Using Pinhole-Ring Modal

The photon sieve is a kind of diffractive optical element proposed to improve the focusing ability of soft X-rays.It is formed by constructing a series of pinholes arranged in the rings on the basis of the Fresnel zone.Because of its high resolution,light structure and wide range of applicable wavelengths,it is widely used in physical and biological fields such as space telescope,lithography,microscopy,and bionic eye.At present,the design of the large photon sieve faces the problems: the design is too inefficient,the size of the pinhole on the edge too small to be processed,and the apodization is too dependent on experience.In this paper,based on the pinhole diffraction model of the photon sieve,it is proposed to use the "pinhole-ring" as the basic unit to study the focusing characteristics of the photon sieve.Through a large number of data simulations,the influence about the diffraction field characteristics of a single pinhole-ring by the size and density of the pinholes is studied,and compared the different concepts of the pupil functions of the equidistant apodization and the unequal apodization,we found that the unequal apodization is more accurate for the actual situation.In the fourth chapter of the thesis,through theoretical derivation,the pinholering diffraction model used to quickly calculate the diffraction field of the large photon sieve is studied and its application conditions are perfected.In the fifth chapter,the simplified pinhole-ring model is obtained to guide the appodization design of the large photon seive,which greatly improves the design operability and efficiency of large photon sieve.Finally,in the sixth chapter of the thesis,the design of a large photon sieve with an aperture of 0.2m and a focal length of 1m is carried out,and the accuracy of the pinhole-ring diffraction model and the rationality of the simplified pinhole-ring diffraction model is verified.At the same time,the partitioned apodization design with the control of pinhole diameter was proposed,which improved the diversity and effect of apodization design.Based on the research of this paper,some problems in the design of the large photon sieve are solved,and new design methods and ideas of large photon sieve are provided.After using the pinhole-ring model and the simplified pinhole-ring model,the calculation time of the diffraction field of the large photon sieve is reduced to 1 in 10,000,and the diameter of the edge pinhole can be increased to 5 times or more than that of ordinary apodization.The method of apodization design is also more abundant and accurate.