Patent ID: 8267538

Claim:
An illuminating device, comprising: a light source having a light emitting surface; and a light diffusing plate comprising: a light pervious substrate having a lower surface adjacent to the light emitting surface and an upper surface at an opposite side of the substrate to the lower surface, a through hole being defined in the substrate to expose a central portion of the light emitting surface of the light source, a cross section of the through hole being a polygon with a plurality of sides; and a light diffusing structure formed at the upper surface, the light diffusing structure including a plurality of first lens arrays radially extending from the through hole and a plurality of second lens arrays each arranged between two adjacent first lens arrays, the number of the first lens arrays being equal to that of the sides of the cross section of the through hole, each of the first lens arrays comprising a plurality of column shaped lenses parallel to each other and arranged at a corresponding side of the cross section of the through hole with the aligning direction being perpendicular to the corresponding side, the column shaped lenses in each of the first lens arrays having a same length as the corresponding side of the cross section of the through hole.