Fourier-transform method for the design of wideband antireflection coatings.

An iterative correction process, recently incorporated into the National Research Council of Canada Fourier-transform thin-film synthesis program, is applied to the design of wideband antireflection coatings. This type of problem is different from those solved in the past by this method. It cannot be handled in a practical way without a correction process. We consider in detail the effects-critical for this application-of constraints on the refractive indices and overall thicknesses of the solutions. Our graded-index and multilayer designs have a remarkable resemblance in performance and refractive-index structure to results obtained by more conventional techniques. The Fourier-transform method is of interest because of its speed and versatility.