4. (30 pts) We have a thin film (silver) of thickness of 85m. We are trying to measure its permittivity, e(f) = &' f) - je" (f). Silver is lossy and its permittivity depends on frequency. We would like to characterize that over visible band, namely to obtain permittivity data for frequency range of 450-650 THz. a) (10 pts) Design and explain an experiment set-up we can find permittivity over the desired frequency range. (We can measure power intensity) b) (20 pts) Determine and present the required equations. 4. (30 pts) We have a thin film (silver) of thickness of 85m. We are trying to measure its permittivity, e(f) = &' f) - je" (f). Silver is lossy and its permittivity depends on frequency. We would like to characterize that over visible band, namely to obtain permittivity data for frequency range of 450-650 THz. a) (10 pts) Design and explain an experiment set-up we can find permittivity over the desired frequency range. (We can measure power intensity) b) (20 pts) Determine and present the required equations