[1] [1] Harris M, Macleod H A, Ogura E P, et al. The relationship between optical inhomogeneity and film structure. Thin Solid Films, 1979 ,57(1): 173～ 178

[7] [7] Jacobsson R. Light reflection from films of continuously varying refractive index, in Progress in Optics, E. Wolf,ed. Amsterdam:North-Holland, 1965,(5)Sec. 2

[8] [8] Jacobsson R. Inhomogeneous and co-evaporated homogeneous films for optical applications, in Physics of Thin Films, G. Hass, M. H. Francombe, and R. W.Hoffman, eds. New York: Academic, 1975,8: 51 ～ 98

[9] [9] Tikhonravov A V, Trubetskov M K, Brian T, et al.Influence of small inhomogeneities on the spectral characteristics of single thin films. Appl Optics, 1997,36(28) :7188～7198

[10] [10] Epstein P S. Reflection of waves in an inhomogeneous absorbing medium. Proc Natl Acad Sci, 1930, 16 (10):627～637

[11] [11] Monaco S F. Reflectance of an inhomogeneous thin film.J Opt Soc Am,1961,51(3):280～282