Ordinary, unpolarized light can be thought of as an equal mixture of clockwise- and counterclockwise-rotating, circularly polarized waves. To create pure, circularly polarized light, a filter can absorb one polarization state and let the other pass through. Such filters are not hard to make, but they are inefficient, since half of the initial light is lost. Liquid crystals are known to emit circularly polarized light, and light from certain semiconductors can become polarized when a magnetic field is used [1]. But these systems are rather large and inflexible in their design.
True, but this ignores lasers which emit linearly polarized light, which can be circularly polarized with a quarter-wave retarder. But there are probably advantages to having it all as a monolithic compact system.
(I also wonder what will happen when someone notices that this system uses a swastika shape, which from a technology standpoint is not particularly surprising — you need a chiral shape, and straight lines are generally the easiest to etch (it has to be a pattern supported by the crystal structure of the material). But given the conservapedia invent-a-furor over relativity, who knows what will happen in the blogohedron?)
