The phase shift on reflection at a double-layer system is treated by using a modified Malé nomogram. For given materials, layer thicknesses are calculated so as to provide a perfect optical-impedance match with zero reflectance. With the system in this state, the phase shift is an extremely sensitive function of small changes in the optical parameters. An experimental application is proposed which uses the effect for the detection and comparison of changes in the optical parameters of a double-layer system.
B. O. SERAPHIN, "Phase Shift on Reflection at a Double-Layer System," J. Opt. Soc. Am. 52, 912-917 (1962)