A system, including an illumination module that comprises (a) a first traveling lens acousto-optic device; (b) a light source for illuminating the first traveling lens to provide an input beam that propagates along a first direction; (c) illumination optics for outputting an output beam that scans the object at a second direction; a detection unit; and a collection module for collecting a collected beam from the object, wherein the collected beam propagates along a third direction; and optically manipulating the collected beam to provide a counter-scan beam is directed towards the detection unit and has a focal point that is positioned at a same location regardless of the propagation of the collected beam along the third direction.