Shadowing causes form birefringence in optical thin films that are deposited at oblique incidence. For light incident in the plane containing the direction of deposition and the substrate normal, the TE and TM polarizations in the film are decoupled, and field transfer can be described using 2 × 2 matrices. The three principal indices of birefringent films are deduced from measurements made on narrow-band interference filters. In one example refractive indices of 2.688, 2.429, and 2.452 were computed for TiO<sub>2</sub> deposited at 27° to the substrate normal. Both TiO<sub>2</sub> and ZrO<sub>2</sub> behave as positive biaxial media.
© 1985 Optical Society of America
I. J. Hodgkinson, F. Horowitz, H. A. Macleod, M. Sikkens, and J. J. Wharton, "Measurement of the principal refractive indices of thin films deposited at oblique incidence," J. Opt. Soc. Am. A 2, 1693-1697 (1985)