High-performance glass-ceramic/copper multilayer substrate with thin-film redistribution

Method and apparatus for monitoring the deposition of a material or materials upon a substrate using atomic absorption techniques. Radiant energy is directed through a flow of evaporant during a deposition process. The radiation contains spectral emission lines absorbable by the evaporant as well as emission lines not absorbable by the evaporant. Changes in the transmission of one or more non-absorbable lines are used to compensate for changes in the absorption of absorbable lines of interest that are caused by misalignment or displacement of the optical elements during the deposition process.