1. A 3-D depth camera system, comprising: (a) an illuminator, the illuminator comprising: (i) at least one collimated light source which provides a collimated light beam; (ii) a diffractive optical element which receives the collimated light beam, and creates a plurality of diffracted light beams which illuminate a field of view including a human target; (b) an image sensor which provides a detected image of the human target using light from the field of view, the image sensor includes a phase mask which adjusts the detected image so that a point spread function of each diffracted light beam which illuminated the human target is imaged as a double helix; and (c) at least one processor associated with the image sensor which determines depth information of the human target, and in response to the depth information, distinguishes motion of the human target in the field of view.