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The real and imaginary parts $$\left(\mathrm{n}_{\theta}+i \kappa_{\theta}\right)=\sqrt{\epsilon_{\mathrm{r}}-\sin ^{2} \theta}$$ have been plotted in Figure (10.6.8) as a function of the angle of incidence, θ, for room temperature copper and for a wavelength of λ= 0.5145 microns (see Table(10.1)). As can be seen from the figure, the angular dependence of the indices nθ, $$\kappa$$θ is not very pronounced. For a lossy material such as copper that has a complex dielectric constant the reflectivity, ER/E0, is complex; that is, the phase shift between the incident wave and reflected wave electric vectors is neither 0 (in phase) nor 180 (out of phase). The real and imaginary parts of the reflectivity have been plotted in Figure (10.6.9) as a function of the angle of incidence for S-polarized 0.5145 micron light incident on room temperature copper; the absolute value of the reflectivity has been plotted in Figure (10.6.10).