The refractive index measured by the Abeles method can have a serious error because of a film transition layer. The effect is different depending on which side of the film the layer exists. Calculation is chiefly made for a surface transition layer which is more realistic than an inner one in the case of deposited films. The following error characteristics are elucidated for a thin surface transition layer: (1) The error is a cotangent function of the film thickness. (2) It is proportional to the transition layer thickness. (3) It increases as the refractive index along the transition layer gets closer to the averaged index of the air and the film. (4) It is almost independent of the substrate index ns except when ns is close to the film index.
© 1984 Optical Society of America
Ikuo Awai and Jun-ichi Ikenoue, "Effect of film transition layers on the Abeles method," Appl. Opt. 23, 1890-1896 (1984)