Design?Fabrication And Test Of Microstructure Fresnel-pressed Prisms

Microstructure Fresnel-pressed prisms play an important role in the treatment of strabismus.However,the technology of microstructure Fresnel-pressed prisms is mainly monopolized by foreign countries at present,such as 3M.And there is no report that the enterprise or research institute designs and manufactures the Fresnel-pressed prisms independently in China.Aiming at this problem,this paper takes the hard film prism made by polymethyl methacrylate(PMMA)as the research object,and Theoretical and experimental research has been carried out on the design?optical parameter derivation and numerical simulation?fabrication?assembly and testing of the microstructure Fresnel-pressed prism.The main work and conclusions of this paper are as follows:1)The design of the microstructure Fresnel-pressed prisms is studied,and three parameters related to the microstructure of the lens surface are proposed:the bottom angle?,the oblique angle?,and the period length W.It is determined that the optimum range of the bevel angle?is 2°-3°,and the optimum range of the period length W is 600um-800um.For the microstructure Fresnel-pressed prisms with PMMA material,a closed assembly scheme is designed to effectively protect the surface microstructure of the lens.A kand of combined Fresnel-pressed prisms and its optimization method are proposed to reduce the influence of lens tilt on the prism power.2)The derivation of the optical parameters and numerical simulation of the microstructure Fresnel-pressed prisms are studied.The mathematical expressions of the prism degree,transmittance and distortion of lens are derived.According to the mathematical expression of the prism degree,the value of the bottom angle?corresponding to the lens of different prism degrees is obtained,which provides parameters for the fabrication of microstructure Fresnel-pressed prisms.Based on the expression of transmittance,the author simulates the transmittance of the microstructure Fresnel-pressed prisms of PMMA,PVC and PS.The simulation results show that the PMMA lens has the highest transmittance.The simulation results of the distortion show that the PVC lens is slightly better than the PMMA lens.3)The fabrication of the microstructure Fresnel-pressed prisms are studied.The 7075 super-hard aluminum alloy was used as a material to produce a stencil of microstructure Fresnel-pressed prisms with a diamond lathe.,and the surface finish of the stencil reaches 14 grades.Using the hot stamping process,the surface of microstructure on the stencil was successfully transferred onto the PMMA substrate under the conditions of 180?and 130 kg/cm ~2.The batch production of Microstructure Fresnel-pressed prisms is realized.Using the vacuum pump,ultrasonic welding machine and some mechanical devices and controllers designed by this subject,the assembly system of the hard film pressing prism is actually built,and the closed hard film pressing prism assembly scheme is realized.4)The test of the microstructure Fresnel-pressed prisms is studied.A prism measuring system and a transmittance measuring system were designed and built.Prism measurement and transmittance measurement were performed on three sets of microstructure Fresnel-pressed prisms,whose prism degree were low,medium and high.The measurement results show that the prismatic error of the microstructure Fresnel-pressed prisms sample which produced by this subject meets the requirements of the national standard,and the transmittance is more than 80%.