Methods of and systems for illuminating objects using planar light illumination beams having substantially-planar spatial distribution characteristics that extend through the field of view (FOV) of image formation and detection modules employed in such systems. Each planar light illumination beam is produced from a planar light illumination beam array (PLIA) comprising an plurality of planar light illumination modules (PLIMs). Each PLIM comprises a visible light emitting diode (LED), a focusing lens, and a cylindrical optical element arranged therewith. The individual planar light illumination beam components produced from each PLIM are optically combined to produce a composite substantially planar light illumination beam having substantially uniform power density characteristics over the entire spatial extend thereof and thus the working range of the system. Preferably, each planar light illumination beam component is focused so that the minimum beam width thereof occurs at a point or plane which is the farthest or maximum object distance at which the system is designed to acquire images, thereby compensating for decreases in the power density of the incident planar light illumination beam due to the fact that the width of the planar light illumination beam increases in length for increasing object distances away from the imaging optics. By virtue of the present invention, it is now possible to use both LEDs and high-speed CCD-type image detectors in conveyor, hand-held and hold-under type scanning applications alike, enjoying the advantages and benefits that each such technology has to offer, while avoiding the shortcomings and drawbacks hitherto associated therewith.