System and methods for filtering electromagnetic visual, and minimizing acoustic transmissions
View Patent ↗A combination of filters for filtering selected wavelengths of electromagnetic radiation is provided on a transparent substrate such as a plastic film or glazing of a window. The combination of filters prevents or attenuates the passage of wavelengths through the substrate which would pose a security risk. The combination of filters is useful to prevent unauthorized data collection and information exchange from or within buildings or otherwise prevent such unauthorized data collection and information exchange from, for example, computer monitors or screens, personal digital assistance, and local area networks. The substrate with the combination of filters may be in the form of a bag or a tent.
1. A transparent anti-surveillance security apparatus for preventing or attenuating the passage therethrough of electromagnetic wavelengths which pose a security risk; said apparatus comprising a transparent substrate and a combination of filters connected to said substrate, said combination of filters comprising a first light filter, wherein said first light filter comprises a plurality of dielectric and IR reflecting metal layers, wherein said dielectric of each dielectric layer has an index of refraction in the range of about 1.35 to 2.6, and wherein said light filter has an IR transmission at wavelengths between 780 nm and 2500 nm of no more than 50% and has a sheet resistance of less than 4 ohms per square to attenuate radio frequency interference (RFI).