#410Polarization Filter

A backlit birefringent crystal viewed between two rotating polarizers. Malus’s law I = I0·cos²Δθ dims the field as the analyzer turns, while a stressed retarder adds a wavelength-dependent phase Γ = 2π·R/λ; the full Jones transmission is integrated across the spectrum, so different λ interfere in and out to paint the shifting Michel-Lévy interference colours over a Maltese cross. Move the pointer and scroll to rotate the two polarizers.