Design Of Refractive/diffractive And Reflective/diffractive Astronomical Telescopes

The modern space telescope become more and more large and spatialization, required to improve the space telescope’s optical receiver,resolution and detection accuracy and range.In the design and application of space-based telescope, the diffractive optical element shows broad application prospects and important value.This topic studied the diffraction optics combined with refraction device and refraction device separately.Used diffraction structure of high refractive index model and improved method of optical design,has designed a variety of optical devices.Articles introduces the method of PWC which described primary aberration theory in refractive/diffractive hybrid optical system, and apply this theory further to reflective/diffractive hybrid optical system. Etching diffractive optical element on the mirror is conducive to the correction of system aberration,reducing the generation of the secondary spectrum,achieving the system requirement of a large field of view,and improving the image quality.This design method can reduce the production costs,and can effectively make the whole optical system structure more compact,reduce the astronomical and other large optical systems for demanding production materials, strengthen the system’s ability to adapt to external environment,without imposing excessive requirements above in the production process,or even reduce the difficulty making.The main topic of the work has following several aspects:Firstly,according to the current development of the telescope optics system design,I want to use a new kind of method that add a diffractive optical element to further strengthen the imaging quality of the astronomical telescope.This part has studied the basic nature of the diffractive optical element,and laid the foundation for future research work.Secondly,This part has determined the design of the optical system,analyzed the high refractive index design method and doublet model of the hybrid refractive/diffractive optical system and designed a system of a focal length of4000mm,a diameter of500mm,numerical aperture of0.0325,field of view angle of0.5°,working band of0.5μm～0.8μm.The program of dsigning optical system which based on the reflective/diffractive hybrid optical system.and use examples to demonstrate the feasibility of two design options.Finally,according to the optical properties of diffractive optical element and the design principles of reflecting telescope,I have designed a reflective/diffractive hybrid large-diameter field of view Cassegrain telescope.This system have a diameter of500mm,a system focal length of2000mm,a field of view angle of3.2°.And analyzed the imaging properties,influencing factors and improve way in different Focal length or View Angle.