Shielded Optical Windows

Shielded windows protect electronic equipment from EMI/RFI radiation. Shielding Express Inc. shielded windows come in two constructions: woven screen laminated between polycarbonate or glass and wire mesh homogeneously imbedded in molded acrylic. Each provides up to 95% optical transmissivity in viewing of characters and displays while, at the same time, dramatically attenuating EMI/RFI.

High level shielding effectiveness against EMI/RFI with high optical transmissivity

Some electronic equipment operation can be temporarily impaired or it may become irrevocably damaged by exposure to radiated electrical energy in the form of EMI/RFI.  Often times it is the most sensitive, most expensive and critical equipment which may experience this type of degradation.  In these cases, the EMI/RFI signals may gain access to the sensitive electronics circuitry inside the equipment through various indicative type performance or viewing devices, that are necessary for human interaction/interpretation such as digital read-outs or displays (including touch-screens).  These read-outs and displays are designed specifically for high visual optical transmissivity, but generally also exhibit low shielding effectiveness against EMI/RFI.

Shielding Express Inc. has developed a complete product line of shielded optical windows that are designed to provide high visual optical transmissivity while preventing the transmission of deleterious EMI/RFI.  These windows can be installed so as to become an integral part of an equipment display.   Shielded windows are available with both woven conductive metal screen laminated between polycarbonate or glass and knitted wire-mesh homogeneously imbedded in a clear or colored acrylic substrate. These unique windows are designed to allow up to 95% clarity in viewing characters or displays while, at the same time, introducing a high degree of shielding, thus preventing equipment damage due to incident radiated electrical energy.

Key Features

1. Windows are constructed using a full-lamination process that results in the conductive wire mesh being completely encased. This permits operation under severe environmental conditions.

2. Different wire mesh patterns and metal alloys allow for a selection of performance characteristics most suitable to the customer's needs.

3. The molded plastic window substrate can be supplied in several preferred colors for improved viewing.

4. Windows may be mounted directly to the equipment interface via a conductive gasket and fasteners, or mounted within a metallic bezel.

Typical Shielding Effectiveness (dB):
 

7" X 9" Test Window with Woven Screen Mesh SS/Ag Blackened 0.0012" dia. wire	200MHz	400MHz	800Mhz	1000 MHz
50 opi	49	50	50	50
80 opi	62	59	57	56
100 opi		64	63	62

Note: Shielding effectiveness will vary depending upon the selection of wire diameter, metal alloy, and screen openings per inch (OPI).  The values of shielding effectiveness for the windows listed in the table above are typical.  The results were obtained from tests conducted at Shielding Express Inc. utilizing a modified version of MIL-STD-285.  Test windows were nominally 7" X 9"
A wide variety of shielding materials and window features are available (see information below) to meet the requirements of your application.

            
Available materials; glass, ploycarbonate, acrylic, and polarizer.