<p>An illumination system having an array of individually controllable optical elements is disclosed, wherein each element is moveable between a plurality of orientations which may be selected in order to form desired illumination modes. The illumination system includes a controller to control orientation of one or more of the elements, the controller configured to apply force to the one or more elements which at least partially compensates for force applied to the one or more elements by a burst of radiation incident upon the one or more elements.</p>
