This article deals with the design, fabrication, and characterization of optically transparent electromagnetic screens to protect optical sensors against high-intensity radiated fields. To ensure the best tradeoff between high optical transparency over the entire visible light spectrum and high shielding effectiveness at microwaves, micrometric mesh metal films printed on glass substrates were selected. Changing the micrometric mesh pattern allows reaching various shielding effectiveness values required for different applications, but implies important adjustments of the design and fabrication processes. The variation of the number of contact ribbons between the mesh screen and its direct peripheral area consists of an alternative solution to modify the screen shielding effectiveness, while keeping the meshed part of the screen identical. An analytical model, which predicts the shielding effectiveness variation measured under statistically uniform illumination in a reverberation chamber as a function of the number of metal ribbons and the aperture sizes between them was specifically developed. Experimental results follow the trend predicted by the analytical model. As a result, adjusting the number of peripheral contact ribbons enables the shielding effectiveness to be fitted to specified requirements at constant optical transparency.

This article presents the design, fabrication, and characterization of an active electromagnetic shield intended to dynamically protect optical and electromagnetic sensors against high intensity radiated fields. The shield exhibits high and constant optical transparency level over the entire visible light spectrum thanks to a micrometric mesh metal thin film printed on a glass substrate. The central micrometric mesh area is separated from the peripheral ground plane of the shield by a peripheral slot. This slot is fitted out with p-i-n diodes and resistors, connecting electrically the central micrometric mesh area and the ground plane. The aim of these components is to dynamically control the shielding effectiveness of the screen, by using the conducting (ON) or blocking (OFF) states of the p-i-n diodes. Accordingly, the shielding effectiveness can be set at high level to protect the system against high intensity radiated fields, and conversely at low level to both prevent system electromagnetic self-perturbation and increase the sensitivity of the internal electromagnetic sensors. Dynamic control of the shielding effectiveness of the fabricated screen, whose optical transparency is close to 85% over the entire visible light spectrum, is fully demonstrated. A shielding effectiveness contrast ranging from 5 dB to 24 dB between the ON and OFF diode states was measured in the 2-10.5 GHz frequency range in a reverberation chamber.

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This paper concerns the protection of electro-optic and electromagnetic sensors embedded into a metallic cavity equipped with a window made of a non-electrically conducting material and optically transparent over the visible light and/or infra-red spectrum. In the presence of high intensity radiated fields, the cavity must be appropriately shielded to protect those sensors, this protection being detrimental to EM sensors sensitivity in their absence. We propose here an automatic and quasiinstantaneous activation of an electromagnetic shield printed on the window glass through the detection of the impinging electromagnetic field. The presented solution is based on thin micrometric mesh-metal film deposited on a glass substrate surrounded by a parallel arrangement of p-i-n diodes polarized by the EM field source itself. An experimental validation is performed using a reverberation chamber to generate the electromagnetic field stress while performing a shielding effectiveness measurement using the nested reverberation chamber test setup.