Disjoint Multipath Source Routing Protocol with route maintenance

An electronic quick change cartridge for a welding helmet. The cartridge base is formed of an optically dense polycarbonate or like material that acts as a passive filter to provide eye protection during the welding process. A port in the base receives a variable density LCD cell and a cavity formed in the base receives the electronics for driving the cell. Optical masks prevent light leakage through any interfaces of the structure. When low light levels are present, the welder views a work piece through an essentially transparent or slightly opaque LCD cell. When an arc is struck, the LCD cell darkens to a shade corresponding to the shade of the surrounding polycarbonate material. The welder then can view the work piece through the LCD cell and all the optically unobstructed portions of the polycarbonate base surrounding the LCD cell thereby to have an expanded viewing area during the actual welding operation.