Error considerations in the design of a two-layer antireflection coating

This paper details the error considerations in the design and construction of a two-layer antireflection coating on KCl. Methods of choosing the most appropriate design, which allows the production of a practical coating of low absorptance and reflectance, are discussed. Experimental methods of minimizing layerthickness errors are also discussed. These methods have been applied to the production of a chalcogenide glass two-layer coating consisting of Ge(30)As(17)Te(30)Se(23) and As(2)S(3). Both the reflectance and absorptance of this coating were found to be 0.02% at the design wavelength of 10.6 microm.