A light diffuser plate includes an optical matrix having opposite first and second ends that are opposite to each other in a first direction, alight incident surface, and a light exit surface opposite to the light incident surface in a second direction transverse to the first direction. The optical matrix is formed with a plurality of elongate holes, each of which extends through the first and second ends and each of which has a cross-section transverse to the length thereof. The cross-section of each of the holes has a periphery that has at least a curved segment which extends curvedly.