METHOD AND APPARATUS FOR ILLUMINATING A DEFINED AREA OF AN OBJECT

An optical imaging system includes a light source, a light detector and an aperture plate. The light source includes a plurality of light emitting devices which emit light that is directed toward an object to be illuminated. The light detector is positioned to view the object illuminated by the light source. The aperture plate is positioned relative to the light source to block a first portion of the light emitted by the light source and to allow a second portion of the light emitted by the light source to pass therethrough to illuminate a pre-defined area of the object. The aperture plate includes a plurality of spaced apart apertures formed through the thickness thereof. Each aperture corresponds to a respective light emitting device. Each aperture of the aperture plate is defined by a first opening formed in the thickness of the aperture plate and a second opening formed in the thickness of the aperture plate. The second opening partially overlaps the first opening and is partially offset from the first opening. The first and second openings' planar shapes match the shape of the desired illumination area, with the first openings being smaller than the second openings. A method for illuminating a defined area of an object includes the steps of energizing one or more light emitting devices of a light source in an optical imaging system, which energized light emitting device or devices emit light that is directed toward the object to be illuminated. The light is passed through particularly-shaped apertures, such as described above, formed in an aperture plate positioned between the light source and the object to be illuminated. The apertures in the plate only allow light passing therethrough to impinge on the object at a pre-defined area thereof.