The wavelengths were selected to avoid interference from colder heat transfer surfaces. Automatic calibration, fault detection, and alarms are provided to interface with a plant's control system. It contains a cubic beam splitter to direct light to the weldment and use reflected light from the weldment to form an image. Welding beam splitter. The beamsplitter is inside the welding torch housing.
Light is directed from a lamp concentric with the welding torch onto the weld bead.
Light reflects back from the work piece and enters a lensing system in the weld torch housing. A video camera captures the reflected beam and converts it into an image of the weld bead. NASA Tech Briefs, May 1991. That is, the filler material will flow readily over both metal surfaces and securely adhere to both metals. Ideal joint clearance for thin wall brazing is from 0.001 to 0.002 inch.