Bright and dark helices of light.

Laser beams can be made to form bright and dark intensity helices of light. Such helices have a pitch length on the order of a wavelength and may have applications in lithography and the manipulation of particles through optical forces. The formation of bright helices is more strongly constrained by optical resolution limits than that of dark helices, corresponding scaling laws are derived and their relevance for photo-lithography pointed out. It is shown how to arrange dark helices on a grid in massively parallel fashion in order to create handed materials using photo-lithographic techniques.