Studies On Precision Injection Molding Process Of Diffractive Optical Elements

With the development of science and technology,diffractive optical elements are more and more widely used in optical systems due to their special properties.There are many processing methods for diffractive optical elements.Compared with mechanical processing and photolithographic processing technology,optical components processed by precision injection molding technology have the advantages of lightweight and low cost.In the current precision injection molding of diffractive optical elements,the determination of the optimal parameters is complicated due to the existence of the microcavity,and the microstructure forming error is large.In this paper,an injection mold is designed for diffractive optical elements.The effects of the molding process on the replication of diffractive microstructures are studied through simulation experiments and injection molding experiments.Firstly,the principle and process of precision injection molding of microstructured components were studied.Analyze the molding principle and screw plasticization principle of precision injection molding machine,study the influence of different process parameters on the filling of microstructures in each process,and provide a theoretical basis for the next step of process parameter optimization.Secondly,research on the working principle of diffractive optical elements and the theory of diffraction efficiency,and determined the design scheme of the runner system,cooling system,exhaust system,and demoulding mechanism of the mold,and analysis and selection of software and equipment required for simulation experiments and injection molding experiments.Then,it proposes to optimize the process parameters and determine the best parameter combination by the Taguchi method and weighted comprehensive scoring method.In the first stage,orthogonal experiments were designed based on the Taguchi method to determine the process parameters that significantly affected the microstructure height and cycle width of the plastic surface.In the second stage,a weighted comprehensive scoring method is used to weigh the two evaluation targets,and the best combination of process parameters is determined by the average analysis of the comprehensive score values.Finally,the actual effect of process parameters on the microstructure replication during the molding process was studied.The single-point diamond lathe machining process of the diffractive microstructure core is analyzed and single-factor injection experiments are performed for different process parameters.Then the microstructure height and product quality are used as evaluation criteria for quantitative analysis.To reduce the microstructure forming error,an error compensation model was established and a compensation experiment was performed.The height of the microstructure before compensation was 0.8933 ?m,the height of the microstructure after compensation was 1.0186 ?m,and the height error after compensation was reduced from 0.1867 ?m to 0.0614 ?m compared with that before compensation.