Abstract text

A method is provided for the determination of the time to terminate the deposition of an optical thin film using an exact model for the reflectance. This model is used to fit the reflectance measurements to determine the deposition rate, from which the time to deposit the entire layer is determined, as well as finding the admittance of the base stack at the beginning of the current layer. The layer deposition is terminated at the calculated time resulting in precise thickness control. This ability to fit the base admittance enables the determination of the reflection model parameters for each layer being deposited so that the accuracy of each layer is independent of previously deposited layers. This means that there is no build up of errors from layer to layer as the deposition progresses, enabling the deposition of coating designs with higher precision, including non periodic and non quarter wave designs.