A mirror with a larger effective critical angle can be made by exploiting diffraction (with non-zero losses) that occurs from stacked multilayers. The critical angle of total reflection, in degrees, becomes approximately , where  is the "m-value" relative to natural nickel.
A mirror with a greater effective critical angle can be created through the use of diffraction effects from stacked layers, which involve some energy loss. As a result, the critical angle of total reflection approaches , where  is the "m-value" relative to natural nickel.