Research On Optical Key Technology For Wide Field High Resolution Infrared Space Telescope

The state of the art of the infrared space telescope was reviewed to make theconclusion that the future development trends of the infrared space telescope are higherresolution, higher sensitivity and larger field of view.This thesis focuses on the optical technology of the wide field infrared spacetelescope, and provides the main points and creativity in the following.(1) Schmidt Camera with field of view9.6°was introduced, and the relative apertureis1/2while the effective focal length is560mm. The athermal design of the Schmidtoptical system exempts the adjustment of the back focal length when the ambienttemperature is varying from-10to+40degree Celsius.The lightweight design of the spherical mirror and the optimization of the heavyloading tube were carried out. The optimized weight of the mirror is12.7kg, while it isequal to79%of the origin design.Stray radiation simulation determinated the effect of the stray radiation in theSchmidt Camera, and it confirmed that the baffles and shields design in the Camera ishelpful to suppress the stray radiation.Wave front coding mask was adopted to extend the depth of focus in Schmidt system,and it could be used to make an athermal Schmidt system, which could keep the consistentperformance under the ambient temperature varying from-60to+60degree Celsius.Tolerance optimization methods were summarized and applied to the Schmidtsystem design. It was concluded that the tolerance operands method and the Incident angleminimization method were the most useful method among those.(2) The space based medium resolution infrared system was analyzed to discuss thetechnical approach of the wide field infrared telescope.The fish eye lens combined with image rotation was proposed to cover the106°fieldof view. The optical design of Scanning Camera was demonstrated, and the tolerancebudgets of the image rotation prism were given. The tolerance budgets of the Pechanprism were implemented based on the sequence ray-tracing model, which was built by thepickup and offset operation in the optical design tool.The harmonic diffractive optical elements made the Scanning Camera to be achromatic aberration free and athermal system, and the quantitative analysis of thediffractive phase was finished. (3) The research progress of wide filed Three Mirror Anastigmat was summarized toillustrate the fact that the specular system could survey a larger field with high resolutionunder the help of the freeform surface. An off axis TMA with50°×50°field of view wasprovided to make a perfect complement and the Zernike type freeform surface was used inthe optical design.Simulation of the infrared stray radiation was conducted to determine the strayradiation level in the wide field off axis TMA, while the shields temperature was swingingbetween173and273K. Temperature should be set below223K in the second and thirdsection and the first section could be set above273K.As the supplement for the current computer aided alignment method, surrogatemodel was proposed to represent the intricate relationship between the misalignmentparameters and the aberration coefficients, so a new reliable solution method of themisalignments could be carried out.As an example, an off axis TMA system was taken to illustrate the process of themodel building and the misalignment calculating.