When looking at liquid crystals in a microscope you often insert the sample between crossed polarizers. The first (often referred to as the polarizer) secures that the incident light is linearly polarized in one specific direction. Since the polarizers are crossed, no light would emerge through the second polarizer if the liquid crystal were absent. But when the light passes through the anisotropic sample its polarization state is altered and thus some of it may pass through the second polarizer (often referred to as the analyzer). The sample now often appears in bright colors, since the effect is wavelength dependent (the phase difference between the two components after passage of the sample is a function of the wavelength of the light). The beautiful pictures in our art gallery are taken in this way.