Research On Optical And Electromagnetic Shielding Characteristics Of Randomly Distributed Ring Grid

With the wide application of electromagnetic waves in various fields,the efficient use of the electromagnetic wave signals required and the shielding of irrelevant electromagnetic wave bands have increasingly attracted people's attention.Among them,the research on the electromagnetic shielding of optically transparent components is of great significance.It is widely used in aerospace optical windows,ultra-precision instrument optical windows,medical electromagnetic isolation room observation windows,vehicle-mounted transparent antennas,and so on.The evaluation indexes of the electromagnetic shielding technology of the optical window include light transmittance,electromagnetic shielding efficiency and stray light distribution.For the metal grid shielding method,the concentrated distribution of stray light caused by diffraction will form imaging interference,which will cause great harm to precision detection.Therefore,reducing the impact of stray light in the optical window and achieving higher imaging quality has become a huge challenge in this field.In addition,the existing shielding methods are still difficult to balance and balance the above indicators.Therefore,it is of great significance to design a new type of metal grid structure to further improve various performances.In response to the above problems,this paper proposes an electromagnetic shielding method based on a randomly distributed ring metal grid.The randomization of the grid structure can be used to better homogenize the high-order diffraction light intensity distribution and improve the imaging quality.According to the scalar diffraction theory,the discrete method combined with Fourier transform is used to obtain the normalized diffraction light intensity distribution of the random ring metal grid;the equivalent circuit method is used to analyze the electromagnetic shielding characteristics of the random ring grid and the equivalent reactance model Correct the coefficient;optimize the optical aperture size,ring radius and center position of the random ring metal grid according to the light transmittance,diffraction distribution and electromagnetic shielding efficiency.The simulation results show that the total light transmittance of the random ring grid under the optimal parameter value is about 95.4%,and the logarithm of the normalized maximum high-order diffracted light intensity is about-5.138,which is the same as that of the same light.The simulation results show that the total light transmittance of the random ring grid under the optimal parameter value is about 95.4%,and the logarithm of the normalized maximum high-order diffraction light intensity is about-5.138,which is the same as that of the same light transmittance.Compared with the two-dimensional orthogonal ring metal grid,it is reduced by more than 95%,and the electromagnetic shielding efficiency of the Ku wave reaches more than 25 d B.The laser direct writing technology and ultraviolet lithography technology are used to process the randomly distributed metal grid structure designed in this paper,and the photoelectric characteristics are tested through experiments.The experimental results show that the metal mesh sample with randomly distributed rings can achieve a high light transmittance,the high-order diffraction distribution is very uniform,and it has good electromagnetic shielding performance.The test indexes are in good agreement with the simulation results,which proves the accuracy of the diffraction model and electromagnetic shielding analysis model proposed for the randomly distributed ring grid.The randomly distributed ring metal grid proposed in this paper can meet the performance requirements of precision optical instruments and equipment,and has very important application value in the aerospace and other fields.