optical element 16 showing both dioptic rings 24 and catadioptric rings 26 returning to fig2 the dioptric rings 24 generally refract light and catadioptric rings 26 generally refract and substantially internally reflect the rays of light typically the dioptic rings 24 are employed relatively nearer to the center of the first optical element 16 as depicted in fig2 and the catadioptric rings 26 are employed farther from the center of the first optical element 16 as depicted in fig2 after the light passes through the first optical element 16 the light is substantially collimated an optical element characteristic that can affect the efficiency of the first optical element 16 includes but is not limited to light collection angles of the optical faces of each of the dioptic rings 24 and catadioptic rings 26 fig4 illustrates the light collection angle u201c u03b1 u201d of the optical face 28 of a dioptic ring and the light collection angle u201c u03b2 u201d of the optical face 30 of a catadioptic ring as depicted the angle of the catadioptic rings 26 typically is more acute than the angle of the dioptic rings 24 in addition with the dioptic rings 24 the radii represent a much larger percentage of the collection angle than on the catadioptic rings 26 typically the dioptic rings 24 and the catadioptic rings 24 do not have a constant height in addition the catadioptic rings 24.