LUXEL CORPORATION
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Filter Support for Strength and DurabilitySubmicron foils usually require some kind of support for mechanical strength and durability. Either metallic mesh or organic polymer film is used for this purpose. Sometimes very small filters can be unsupported if maximum transmission is needed, but they require extreme care in manufacture and handling. Filters made with reinforcement are much more durable during manufacture, shipping, and operation. The standard mesh support is 70-lines-per-inch electroformed nickel, which provides a measured 82% transmission. This material makes an excellent all-purpose foil reinforcement for laboratory or space applications. To meet your needs, additional electroformed meshes are available with varied lines per inch for improved transmission, while other materials can be utilized for greater strength. During filter assembly, mesh is cemented to foils, and then foils are cemented to frames with epoxies suitable for spacecraft and ultra-high vacuum systems. In-house manufacturing tools have been developed that permit the fabrication of metallic ultra-fine wire meshes. Custom fabricated tungsten or stainless steel wire of 10 µm diameter can permit throughput gains of 10 to 15 percent over conventional nickel mesh, and provide double the burst strength due to the higher tensile strength of these materials. In addition, a very high modulus polymer fiber, Vecry® can also be utilized to fabricate meshes where the requirements for increased throughput in the high energy X-ray regions are desired. Vecry also provides more than quadruple the burst strength over conventional mesh. These constructions are available on a custom basis and are quoted accordingly.
Organic polymer films, including polyimide and Lexan® polycarbonate are also used to support submicron films. They can be integrated into the filter construction, either alone or in combination with mesh to provide increased strength and durability. Polyimide is fast becoming the material of choice when an organic film is required. Compared to previously employed polymeric films; polyimide provides increased strength, ability to withstand both cryogenic and high temperatures, and effectiveness in blocking unwanted ultraviolet radiation. In addition, polyimide can be fabricated in a great variety of thicknesses and can also be supplied as a freestanding film. 02/14/2005
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