Optical Filtering


The Optical filtering devices range of RFI filters are designed to give the highest levels of RFI/EMI shielding combined with excellent optical performance. Display quality micro-fine mesh, incorporating proprietary coating is laminated or bonded to glass, acrylic or polycarbonate to offer the most effective and unique solution to shielded display problems.  Electromagnetic Interference (EMI) can be described as any form of electrical disturbance, signal or noise, which interferes with the ability of electrical or electronic equipment to function correctly.

It is also necessary to contain emitted signals from computer and data handling equipment to prevent electronic eavesdropping for example, where these signals may interfere with other sensitive electronic equipment in the nearby vicinity. The simplest way to achieve this is by the Faraday Cage Principle and in effect, this is what happens in most cases (metal frames or casings placed over the source of the emission).

Our optical filtering device and shielded windows are an extension of this principle in that the fine wire mesh acts as a barrier to these emissions but at the same time allowing the operator sight of the display into, or out of the shielded component. The windows on their own will not solve RFI problems but must be an integral part of a fully shielded system.

Optical filtering devices are most commonly produced by incorporating a layer of woven mesh into a sheet of clear acrylic (Per L-P-391D Type 1 Grade C) and machined to fit your specifications. They can be supplied to you from .060 thick.


Optical filtering devices are used in any application where the viewing port has to be optically clear and also shield against unwanted EMI/RFI interference. The mesh that is incorporated in it can provide the needed attenuation, while the gasket and method of termination can provide the desired electrical bond. Gaskets should inhibit moisture and supply conductivity throughout the window. Wire mesh bonded to (Series 400), or Oriented in (Series 600) either sponge or solid silicone can supply this termination. Other typical interfaces include Conductive Fabric over Foam (Series 577), and Particle Filled Elastomers (Series 800).

Battlefield tactics systems
Communication systems
Hand-held computers
Secure laptop computers
Test and measurement equipment
Navigation equipment
Radar applications

Contact Fralock for further information on EMI shielding and RFI shielding products. Request a quote or Call us at 1-800-FRALOCK (372-5625)

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For additional information about us or to begin discussions on your project, click our Quote Request, or call 1-800-FRALOCK (372-5625)