高衍射效率衍射望远镜系统的设计/加工及成像性能测试

为提高衍射效率,设计并制作了口径为300mm的衍射成像系统.该系统的物镜是由一块四台阶位相型菲涅尔波带片通过激光直写套刻和Ar离子束物理刻蚀技术在石英玻璃基板上加工而成.测试了衍射物镜的衍射效率,实验结果表明:衍射物镜在波长632.8nm处的衍射效率为66.4%,达到理论值的82%.搭建了衍射成像系统光路,分别采用10μm星点孔与分辨率板,测试了系统的成像性能.实验测得星点像直径为44μm,分辨率板的极限分辨率达到84lp/mm,接近该系统的理论计算值,表明该衍射成像系统具有较好的成像性能.

Design/fabrication and Performance Test of a Diffractive Telescope System with High Diffraction Efficiency

In order to improve the diffraction efficiency,a diffractive telescope system with 300 mm aperture was designed and fabricated.The primary lens of the proposed system is made form a four-step phase Fresnel zone plate which is fabricated on fused silica substrate by laser direct writing and Ar ion beam etching.The diffraction efficiency of primary lens of the diffractive system was tested.The tested results show that the diffraction efficiency of the diffractive lens at wavelength 632.8 nm is 66.3％,about 82％ of the theoretical value.The light path of diffraction imaging system was built,and the imaging performance was tested by both the star image test and the resolution test.The diameter of the star image is 44 μm and the limit resolution is 84 lp/mm,which are very close to the theoretical values,showing the diffractive system has a good imaging performance.