The production of advanced optical coatings with complex spectral characteristics and high performance is directly dependent on the stability of the deposition process and on the accuracy of the monitoring system employed for controlling the thickness of the constituent single layers. The present contribution is concentrated on the current state in deposition control and manufacturing of coatings with improved precision. As major topics the simulation of deposition processes, modern monitoring concepts, and the handling of errors occurring during the deposition process will be discussed. For illustration of some recent developments, results on the deposition of rugate filters on the basis of an ion beam sputtering process will be presented.