Low optical diffraction random hexagonal structure metallic network conductive films

Abstract

Traditional metallic meshes are a two-dimensional square structure with high optical transmittance loss, and the diffraction of light seriously interferes with the imaging quality of the detection system. In this work a metallic network conductive film with a random hexagonal surface structure is designed. This structure has a higher optical transmittance than conventional square metallic meshes. As a result of the random variables in the structure, it can also suppress the stray light of high-order diffraction. Then we prepare a metallic network conductive film on a ZnS optical window with a line width of 4 μm and a period of 100 μm. The metal lines of the sample are clear, the line width is uniform, and there is no dotted line. The transmission loss of the ZnS optical window is 10.5% in the long-wave infrared band (LWIR) band but only 6.8% in the visible band, which has low energy loss. At the same time, it can achieve uniform optical diffraction, thus reducing the imaging interference to the photoelectric detection system. The numerical simulation results show that the average EMI shielding efficiency is 37.9db, which is in an electromagnetic spectrum range from 0.2 GHz to 20 GHz, and its minimum shielding efficiency is 29.6 dB, which is 3.2 dB higher than the traditional square mesh’s. The random hexagonal structure metallic network conductive films designed and prepared in this paper have excellent optical properties and EMI shielding efficiencies, which is of great significance in improving the comprehensive performance of the graphical optical window.