Simulated And Experimental Research On Glass Molding For Curved Compound Eye Glass Lens

The compound eye lens has the advantages of small size,small mass,large field of view,and high sensitivity,etc.It has the future of being widely used in high-end optical systems such as infrared detection,intelligent guidance,and imaging diffraction in the aerospace,defence,optoelectronic information,biomedical,transportation,and intelligent robotics industries.Compared with traditional manufacturing methods,optical precision molding technology has the advantages of high production efficiency,high processing accuracy,low production cost and suitable for mass production.The current compound eye lens molding technology focuses on the molding of flat structure compound eye lenses,and there is insufficient research on the molding of curved compound eye lenses.In this paper,we focus on curved compound eye lens molding technology,including finite element analysis of the molding process,mold manufacturing and experimental research of molding.Firstly,the theoretical analysis of optical glass molding was carried out to analyze the thermo-mechanical properties and viscoelastic model of optical glass at molding temperature,providing a theoretical basis for the establishment of a finite element model for molding simulation.MSC.Marc finite element software was applied to establish a finite element model and carry out a simulation study on the heating stage,molding stage and annealing and cooling stage of curved compound eye lens molding using K-LCV-161 optical glass and copper-nickel alloy C71500 die.The heating stage simulation determined the shortest heating time and maximum thermal stress in the heating stage;by analyzing the simulation results of different molding temperatures,it was found that the higher the temperature,the lower the lens stress;the study of different molding methods shows that the applied load and the lens stress increase with the molding process in the constant-velocity molding condition,the rate of downward decreases with the molding process and the stress increases with the increase of the molding pressure,in the case of large deformation of spherical preforms,the constant-rate molding condition will lead to the phenomenon that the stress relaxation is hindered by the increase of the downward due to the excessive external force.The effect of different holding pressures on the filling effect and the stress distribution in the eyes was investigated in the holding phase.The annealing stage was simulated and the temperature variation and stress variation curves of the annealing stage were obtained.The final controlled stress in the molding stage was 2.024 MPa,the maximum stress in the holding stage was 1.297 MPa and the maximum stress in the annealing stage was 0.326 MPa.Then,a simplified two-dimensional axisymmetric finite element model of the single-eye structure was established to investigate the formation process of contour offset during the annealing stage.The effects of different annealing process parameters,including holding pressure,holding time and demolding temperature,on contour offset were compared.The effects of different lens structure parameters,including substrate size,substrate curvature radius and fillet,on contour offset were explored.Finally,the die of Ni-P coating on Cu-Ni alloy C71500 substrate was processed by single point diamond turning method.The surface accuracy and surface roughness of the die were tested.The die forming experiment of curved compound-eye lens was carried out,and it was found that the variation trend of profile deviation with radius was basically consistent with the simulation results.