Produced primarily as a sales film, at the same time it is useful as an introductory film on the principles of polarization. Sketches the nature of light waves, the focusing of the light beam, the spectrum, the use of colour filters. Diagrams are employed to explain the theory of polarization. Straight photographic techniques demonstrate many practical uses of polarizing materials, including the abolition of glare through spectacles, car headlamps, reading lamps, aeroplane windows, and the production of colour changes on display posters.