Research On Aberration Inactivation Of Optical Imaging Systems Based On Wavefront Coding

The design aim of optical system is to capture the original features of scene.In the high-quality imaging system,the target can be clearly imaged in the conjugate image plane and the point dispersion meets the requirement of detector pixel size.However,generally the design of optical system is limited by the optical aberration.Superior performance of optical systems will increase the complexity of optical design and also the robustness of optical system will reduce.In view of this condition and backgroud,the dissertation dedicates the theoretical investigation of optical aberration inactivation technique based on wavefront coding and the applying investigation of optical aberration inactivation technique in the design of conformal optical systems and wide-field-of-view systems.Hopefully we can make some contributions on the development and application of modern optical system design and wavefront coding technique.Firstly,the inactivation effect of wavefront coding to the primary aberrations are investigated.These primary aberrations include primary spherical aberration,primary astigmatism and primary coma.Based on stationary phase method,the expression of optical transfer function(OTF)of wavefront coding system with off-axis aberration is derived.The inactivation characteristics for off-axis aberrations under different boundary conditions are studied.Based on wave aberration theory,ray aberration of wavefront coding system with spherical aberration is obtained.According to the ray aberration distribution,the inactivation characteristics for the spherical aberration are studied.The inactivation effects of wavefront coding systems in the presence of several primary aberrations are proved.Secondly,based on the aberration inactivation theory of wavefront coding,the inactivation technique of asymmetrical optical aberration of conformal dome is studied.The properties of optical aberration of conformal dome are studied and the traditional correcting method for aberration of conformal dome is analyzed.The residual aberrations of conformal dome are analyzed when the aberration has a preliminary correction by using the fixed corrector.Then the residual aberration of conformal dome is further smoothed by introducing a generally cubic phase mask with the optimized parameter.Aberration inactivation characteristics of a wavefront-coding conformal optical system are studied in the spatial domain and in the spatial frequency domain.Also the results of aberration inactivation are verified by image simulation appoarch.Conformal dome with fineness ratio of 1,wavelength band of 3.7-4.8?m,and target field of ±30° as an instance is used to verify that the wavefront coding technique can inactivate the asymmetrical aberration of conformal optical system.Finally,the inactivation technique of variational field aberration is investigated based on wavefront coding.Using ray aberration theory,we study the off-axis aberration characteristics of single lens.Based on the wavefront coding technique,the variational aberration characteristics with field are analyzed and a two-lens optical system is design to prove our method.The aberration distribution of two-lens spherical optical system is studied,and the imaging performance is evaluated in the spatial domain and spatial frequency domain.Based on wavefront-coding aberration inactivation theory,we design and optimize a general cubic phase mask.Two-lens infrared optical systems with the full field of 10° and 14° are inactivated using wavefront coiding respectively.Finally,the point spread function(PSF)at 0° field of view is used to decoded the encoded images in order to prove the aberration inactivation performance of wavefront coding.