Research On Electromagnetic Shielding Technology Of Laser Detection System In Complicated Electromagnetic Environment

With development of military technology and optoelectronic countermeasures technique,the electromagnetic environment becomes increasingly severe on future battlefields.The requirement of laser detection system countering complex electromagnetic environment becomes an urgent task.This thesis is studied on the electromagnetic shielding effectiveness,light transmission and imaging properties of metallic grids and ITO transparent conductive films of specific wavelength band.With metal mesh and ITO transparent conductive film filter technology,experiments on electromagnetic waves shielding,transparency and imaging of laser detection system are completed.The effects of structural parameters such as periods and width of metallic grids on electromagnetic shielding effect are analyzed with equivalent circuit model theory.It can be concluded that reducing the period of grid or increasing the line width of grid can improve the capacity of electromagnetic shielding.On the contrary,periods decreasing or width increasing of metallic grid result in better electromagnetic wave permeability in the transmittance of the optical system.The longer the period of the grid and the smaller of the line width leads to the better transmittance.With layered media theory,it can be concluded that the decreasing of the electric conductivity can improve the effectiveness of ITO transparent conductive film shielding and the optical system transmission is inversely proportional to the thickness of the film.The metal-grid fairing is fabricated by laser direct writing method with period of 400 um and line width of 90 um.Transparent conductive film fairings are fabricated by RF magnetron sputtering with the sheet resistance of 10? and 5?.With contrast test methods,the electromagnetic shielding effectiveness,light transmission and imaging properties of metallic grids and ITO transparent conductive film fairings are studied.It can be concluded from the theory and test data analysis in this thesis that ITO transparent conductive film fairing performs better than metal mesh fairing,with considering of same optical transmission considering cost and manufacturing process.