US Patent 6938481 Sight glass and low temperature method of manufacturing the same

An improved lower cost sight glass and a method for producing the same is disclosed, whereby the sight glass is made by placing a transparent component in secure contact with a metallic ring. The contact may optionally be effectuated by temporarily altering the relative dimensions of the metallic ring and the transparent component, placing the transparent component into the inner space of the metallic ring, and then reversing the altered relative dimensions of the metallic ring and the transparent component. A hermetic seal is formed between the transparent component and the metallic ring is by the application of an inorganic sealing compound.