The Key Technology Research On Design And Fabrication Of Folding Imaging System Based On Monolithic Multisurface Optics

Multi-band photoelectric load with the fusion imaging technology has the function of common recognition of geometric and physical characteristics,which can improve target recognition rate and recognition efficiency.It has played an irreplaceable role in field of photoelectric imaging,and has received extensive attention from researchers in recent years at home and abroad.The traditional multi-band photoelectric load generally adopts the optical structure of multi-lens discrete combination,which has the problems of large system volume and weak real-time image processing capability,and it is difficult to meet the requirements of integration and miniaturization in the new photoelectric load.With the development of ultra-precision machining technology,the shape and position high-precision machining of monolithic multi-surface optics is possible,which provides effective support for the optical component manufacturing of the folded optical imaging system and is expected to bring transformative development for multi-band photoelectric load.However,high-performance folding imaging systems face many new challenges in optical design,ultra-precision machining,high-precision detection and performance control.The optical design of the folding imaging system needs to solve the multi-objective optimization problem under multivariable constraints;the processing of monolithic multi-surface optics needs to solve the problem of high-precision generation and detection under the condition of coupled position and shape;solve stray light suppression and high precision assembly problems.Therefore,the optimization design of the folding imaging system based on monolithic multi-surface optics is carried out to realize the high-precision processing and detection of multi-complex surface conformal optical components,breaking the traditional multi-band photoelectric load discrete structure and improving multi-band.The performance of photoelectric load system has important theoretical and practical significance for promoting the development of multi-band photoelectric load in China.In view of the above problems,this thesis focuses on the research and development of multi-band folding imaging systems,and carries out research on key technologies such as optical design,processing,testing and image fusion.The specific research contents cover the following aspects:（1）An optimized design method for folding imaging system based on monolithic multi-surface optics is established.In order to improve the effectiveness of the optical design of the folding imaging system,an optimal design model of the folding imaging system was established based on the classical aberration theory.The experimental verification was carried out with reference to the photoelectric load demand of the autonomous vehicle target detection.The aberration distribution of monolithic multi-surface optics is mastered.The influence of system boundary conditions and thermal parameters is analyzed.The optimization scheme and design parameters of the system are proposed,which laid the foundation for design of multi-band folding imaging system.（2）A high-precision in-position detection and compensation turning method for monolithic multi-surface optics is proposed.Aiming at the high-precision manufacturing problem of monolithic multi-surface optics,the single-point diamond turning process of monolithic multi-surface optics is studied.The accuracy of the position and position error on-machine measurement effectively suppresses the cutting error by the compensation processing method,and realizes the high-quality and high-efficiency processing of the monolithic multi-surface optics.（3）A method for analyzing and suppressing stray light in folded imaging system is proposed.Based on the requirements of photodetector target detection,the model of stray light analysis and suppression of folding imaging system is established based on the property of detector.The basic principles for stray light suppression are defined specifically.The structures including the inner wall light blocking ring,the inner hood and the exit aperture stop are realized which can make the visible light system have a PST value less than10^-5,the PST value of the long-wave infrared system is less than10^-4.（4）An analysis method for assembly error of folded imaging system is proposed.The source of the assembly error is analyzed.The sensitivity analysis method is used to establish the relationship between the system assembly error and the surface error of the folding imaging system.The high precision assembly of the folded imaging system and the final wave aberration of the visible light system are realized.The Peak to Valley（PV）value is 0.980λ,the Root Mean Square（RMS）value is 0.156λ,and the long-wave infrared system has a wavefront PV value of 0.935λand an RMS value of 0.165λ.（5）The image fusion method for folding imaging system is proposed.The ultra-precision turning process ensures high-precision coaxial integration of visible light imaging system and long-wave infrared imaging system,which simplifies the image registration process.The principal component analysis method is used to realize the fusion of dual-band images.The fused image contains more abundant scene information.The target feature is more obvious,which can effectively improve the target recognition rate and recognition efficiency of the unmanned system photoelectric load.（6）The basic implementation method of assembly without adjustment for monolithic multi-surface optics is built.Through the common body design of monolithic multi-surface optics,the shape and positional accuracy of the optics are realized,which lays a foundation for the folding imaging system.The use of plane mirrors are easy to obtain high processing precision and have no fixed optical axis direction.The eccentricity errors between the plane mirror and the monolithic multi-surface optics does not exist.