Problem 5.182

A crystalline plate cut parallel to its optical axis is \(0.25 \mathrm{~mm}\) thick and serves as a quarter-wave plate for a wavelength \(\lambda\) \(=530\) nm. At what other wavelengths of visible spectrum will it also serve as a quarter-wave plate? The difference of refractive indices for extraordinary and ordinary rays is assumed to be constant and equal to \(n_{e}-n_{0}=0.0090\) at all wavelengths of the visible spectrum.