An apparatus includes an illumination lens, an illumination light source for generating illumination light, and a prism made of optical transparent material. The first section on the first surface of the prism has a length that is at least four times as long as its width. The first surface of the prism includes a second section adjacent to the first section for defining the edge of an aperture. The third surface of the prism is configured to reflect the illumination light received from the first section onto the second surface of the prism. At least a portion of the illumination light received from the first section passes through both the second surface of the prism and the illumination lens for projecting illumination light onto a target object within an imaging field of view.