[en] A new method of designing multilayer optical thin film coatings is developed using a new optimization technique. Results obtained demonstrate that the method of damped least squares with indirect reflection derivatives give better and efficient designs compared to other known optimization methods. Many constraints and boundary conditions compatible to the available experimental facilities are incorporated in the method which enables it to give practically realizable designs. The method is successfully applied to design and develop indigenously various types of multilayer optical thin film coatings for different high power laser applications. (author). 20 refs., 5 figs., 3 tabs