Durable metalised windows for hermetically sealed optics
Reynard Corporation, a manufacturer of optical components and custom thin film coatings, now provides high performance metalised windows. These optics are used in a variety of applications, such as windows for cryogenic storage dewars, hermetically sealed detectors, medical endoscopes, heated windows, and other special configurations.
The manufacturing process is a thin film coating method in which a pre-determined pattern of metal is deposited on the surface of the optic. The metal needs to offer good conduction and low corrosion characteristics, therefore typical materials used in this type of product include gold (Au), copper (Cu), and nickel (Ni). The metalised pattern is typically combined with a thin film filter or anti-reflection (AR) coating.
The metal pattern applied can be configured for various requirements. For example, a continuous ring on the edge of an optic provides a surface for hermetically sealing it to a metal surface in airtight applications. A high-transmission window is created by enhancing the substrate with an AR coating on both surfaces. A continuous ring is then added to the outside edge, allowing the window to be hermetically sealed to a metal surface. This configuration can be used to protect a detector from atmospheric or environmental conditions, which is particularly useful in a cryogenic dewar. Reynard's metalisation process is compatible with systems that use the getter process to create vacuum seals.
Other applications such as busbars allow for an electrical conduction path between two or more sections of an optic. Solder pads used in wire bonding or multiple segregated connections can benefit from a metalised coating. Grids or conductive planes can be used to produce heated windows or components designed for EMI protection.