An apparatus for dynamically varying an optical characteristic of a light beam includes an optical element configured to receive a beam of light. The optical element includes at least one sub-wavelength grating formed of a plurality of lines. The apparatus includes at least one actuator connected to at least one component of the optical element and a controller for controlling the at least one actuator to dynamically vary a characteristic of the beam of light that is at least one of emitted through and reflected from the optical element.