Multispectral transparent electromagnetic-wave-absorbing optical window technology based on a random grid

A multimode detection system has stringent requirements in terms of electromagnetic characteristic control and electromagnetic compatibility. To meet these requirements, we designed and manufactured a type of transparent electromagnetic-wave-absorbing optical window based on a random grid (EAOWRG) in this study. Owing to the design and regulation of the materials of the random grid and the structures of the metasurface, the optical window has excellent multispectral transparency, electromagnetic wave absorption, and electromagnetic shielding performance. The experimental results showed that the transmissivity of the EAOWRG in the optical spectral ranges of 460-800 nm and 8-12 µm is above 89.77%, the electromagnetic reflectivity in the frequency ranges of 3.6-7.2 GHz and 14.3-17.7 GHz is not more than - 5 dB, the bandwidth at which the electromagnetic reflectivity is not more than -10 dB is 4.4 GHz, the electromagnetic shielding effectiveness in the frequency range of 2-18 GHz is above 31 dB. The average radar cross section of the detection system using the EAOWRG in the ± 60° angle domain at 6 GHz is 8.79 dB lower than that before processing. The detection system has a good imaging effect in the visible and infrared bands, meeting the requirements of the electromagnetic characteristic control and electromagnetic compatibility, and has good application prospects.