Optical thin film production with continuous reoptimization of layer thicknesses

For various reasons when optical multilayer systems are constructed the thicknesses of individual layers depart from the desired values. This often results in an unacceptable performance of the filter. In this paper a production method for nonabsorbing multilayer coatings is described, which is based on monochromatic transmittance monitoring and which, to a certain degree, compensates for these errors. After the deposition of each layer a computer program is provided with the actual monitoring data from which the layer thickness is deduced. The program then reoptimizes the performance of the system by changing the thicknesses of the remaining layers. A numerical and experimental study has been made of the production of a seven-layer neutral beam splitter on glass. Theoretical data are also given for an AR coating on glass.