Studies Of Hybrid Diffractive-refractive Annular Folded Aperture Imaging Technology

The ultrathin annular aperture imaging system is a new type of imaging optical system which is thin and light.Compared with the conventional optical system,the ultrathin annular aperture imaging system has the advantages of small size,light weight and high resolution.Because the ultrathin annular aperture imaging system is only composed of a single substrate material,the system cannot achieve achromatic,which seriously affects the image quality.Diffractive optical elements(DOEs)have special dispersion characteristics.When they are introduced into the design of an ultrathin annular imaging system,the influence of chromatic aberration can be eliminated without increasing the complexity of the system to achieve high image quality.In this dissertation,the refractive-diffractive hybrid ultrathin annular aperture imaging systems containing traditional DOE and new reflective-diffractive optical element are designed respectively,and the imaging performance of these two systems is studied.In the case of traditional DOEs,this dissertation discusses the design method of the ultrathin annular aperture imaging optical system,and the four-reflection ultrathin annular aperture imaging system is designed with optical plastic polymethyl methacrylate(PMMA)as the substrate material.A DOE is introduced at the exit refractive surface of the system to achieve achromatism of the hybrid optical system.In addition,tolerance analysis and thermal analysis of this system are analyzed to verify the feasibility of the design results.In the case of reflective-diffractive optical elements,the expression of microstructure height is derived in this dissertation.The expressions of diffraction efficiency and polychromatic integral diffraction efficiency are given,which lay the theories for the imaging quality evaluation of the refractive-diffractive hybrid ultrathin annular aperture imaging system with reflective-diffractive optical elements.The refractive-diffractive hybrid ultrathin annular aperture imaging systems with four-reflective and six-reflective structures are designed which use the reflective-diffractive optical elements,and the results of imaging quality evaluation are given.