Abstract

45° angle of incidence in crown glass (n=1.52) is particularly difficult for p-polarization and normal dielectric materials. At that angle the typical normal incidence y_H/y_L ratio for zirconia/silica of 1.414 gives η_H/η_L of 1.794 and 1.114 for s- and p-polarization respectively. This great difference, and almost unity value for p-polarization, leads to very complex designs for even small spectral ranges. Metal layers are not affected to the same extent because the wave in them is virtually evanescent. We use modified admittances (rationalized by multiplying or dividing by cosθ₀, where θ₀ is the angle of incidence in the incident medium) and in this scheme the variation in metallic is almost entirely through the cosθ₀ term. This still shows quite a change for s- to p-polarization but there is considerable contrast between the metal and any dielectric for both planes of polarization, making it possible to achieve something in design.

© 1992 Optical Society of America