Hermetically sealed windows suit optical, laser and infrared applications

Paul Boughton
PA&E is now using its patented ceramic-to-metal sealing technology to manufacture hermetically sealed windows for optical, laser and infrared applications. The innovative bonding properties and polycrystalline structure of PA&E's Kryoflex material enables the company to produce sight or wave-guide windows that maintain high levels of hermetic integrity under extreme environmental conditions. This new product is particularly well suited for space or defence-related Ladar (laser detection and ranging), laser designation/acquisition systems and medical endoscopes.
The ceramic-sealed hermetic windows offer engineers additional advantages beyond high hermetic performance. Because Kryoflex seals at relatively low temperatures, engineers can now choose from a variety of optical glasses such as sapphire, quartz and BK10. These new windows are also designed to be laser-welded to a range of metals including aluminium, titanium and iron/nickel alloys.
Windows produced with this new process are said to be extremely robust and reliable because a key point of failure – solder joint fatigue – is eliminated. They provide a leak rate equal to or less than 1X10-9cc/s helium at 1 atmospheric differential pressure, even when subjected to extreme thermal and mechanical shock and, in medical applications, will maintain integrity after repeated autoclave sterilisation cycles.
Unlike solder- or braze-sealed windows, PA&E's ceramic-sealed hermetic windows do not require metallisation. Eliminating this step can reduce costs and processing time and also enables anti-reflective coatings to be applied after the sealing process, thereby ensuring that the anti-reflective coating is not damaged by subsequent processing.
For more information, visit www.pacaero.com

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