A certain birefringent material has indexes of refraction n1 and n2 for the two perpendicu...

A certain birefringent material has indexes of refraction n1 and n2 for the two perpendicular components of linearly polarized light passing through it The corresponding wavelengths are λ1 = λ0/n1 and λ0/n2 where λ0 is the wavelength in vacuum. (a) If the crystal is to function as a quarter-wave plate, the number of wavelengths of each component within the material must differ by . Show that the minimum thickness for a quarter-wave plate is

(b) Find the minimum thickness of a quarter wave, plate made of siderite (FeO ∙ CO2) if the indexes of refraction are n1, = 1,875 and n2 = 1.635 and the wavelength in vacuum is λ0 = 589 nm.