General Dynamics Land Systems, Inc.

Rosemarie Reilly

Dennis N Harvey

An optical input apparatus (10) for use with a weld evaluation monitor (14) to determine the concentration of hydrogen in a weld arc atmosphere (62) including weld arc plasma and shield gas is disclosed as including an optical fiber bundle (16) having a single optical input (18) and a plurality of optical outputs (22). The optical fiber bundle is disposed to receive, at its optical input, electromagnetic radiation emitted from the weld arc atmosphere and, because the optical fiber bundle has an individual optical fiber path distribution that is completely randomized, to communicate proportional amount of the radiation to each of its optical outputs independent of the angular disposition of the fiber bundle. Radiation having only specific wavelengths of hydrogen, shield gas and background emissions are allowed to pass through respective optical line filters (56) to associated optical transducers (58), which generate electrical output signals having amplitudes representative of the intensities of the hydrogen, shield gas and background emissions. Also disclosed is a signal processing module (12) for receiving the electrical output signals and determining therefrom the hydrogen concentration in the weld arc atmosphere. A method for using the apparatus to determine the hydrogen concentration is also disclosed.

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Bloomfield Hills, MI, United States of America

Rosemarie Reilly