Panel with occluded microholes

Abstract

A panel includes a plurality of microholes arranged in a pattern and filled with light transmissive polymeric material. The light transmissive polymeric material occludes the microholes and is set, or cured, by exposure to an energy source using at least two discrete exposure periods separated by an idle or rest period. The uniformity of the microholes is thereby improved.

What is claimed is: 
     
         1 . A panel, comprising:
 a substantially planar portion including a first planar surface and a second planar surface opposed to the first planar surface;   a plurality of microholes passing from the first planar surface to the second planar surface, each microhole communicating with first and second apertures defined in the respective planar surfaces and having an internal surface therebetween; and   a light transmissive polymeric material disposed within each microhole, the light transmissive polymeric material having a first outer surface substantially coplanar with the first planar surface of the body, a second outer surface opposed to the first outer surface and a central body disposed therebetween; and   wherein the central body of the light transmissive polymeric material has an outer central surface in contacting engagement with the internal surface and wherein the light transmissive polymeric material has a polymeric chain wherein at least 5% of components are derived from an ultraviolet (UV) curable epoxy acrylate oligomers exposed to at least a first UV exposure period and a second UV exposure period separated by a rest interval, the rest interval being a period that extends from the first UV exposure period to the second UV exposure period during which the light transmissive polymeric material is not exposed to a UV source.   
     
     
         2 . The panel of  claim 1  wherein a thickness of the substantially planar portion is greater than a diameter of each of the first and second apertures. 
     
     
         3 . The panel of  claim 1  wherein the light transmissive polymeric material includes repeating units derived from UV curable epoxy acrylate oligomers in an amount greater than 10% of the polymeric chain and further has at least 20% of the polymeric chain derived from aliphatic esters and 5% of the polymeric chain derived from cyclic aliphatic esters. 
     
     
         4 . The panel of  claim 3  wherein the light transmissive polymeric material further includes at least 0.25% of the polymeric chain derived from aliphatic silanes. 
     
     
         5 . The panel of  claim 1  wherein the light transmissive polymeric material contains polymeric units oriented such that the incidence angle of transmitted light is substantially 0 across the outer surfaces of the light transmissive polymeric material present in each microhole. 
     
     
         6 . The panel of  claim 1  wherein the rest interval is at least as long as each of the first UV exposure period and the second UV exposure period. 
     
     
         7 . The panel of  claim 1  wherein lengths of the at least the first UV exposure period and the second UV exposure period and the rest interval are such that an average of respective light intensities measured through the plurality of microholes is substantially equal to an average of the respective light intensities measured through the plurality of microholes when the light transmissive polymeric material is in a workable state before exposure to the at least the first UV exposure period and the second UV exposure period. 
     
     
         8 . The panel of  claim 1  wherein lengths of the at least the first UV exposure period and the second UV exposure period and the rest interval are such that an average of respective optical diameters of the plurality of microholes is substantially equal to an average of the respective optical diameters of the plurality of microholes when the light transmissive polymeric material is in a workable state before exposure to the at least the first UV exposure period and the second UV exposure period. 
     
     
         9 . The panel of  claim 1  wherein the light transmissive polymeric material transmits light through the plurality of microholes with a uniformity substantially similar to a uniformity that the light transmissive polymeric material transmits light through the plurality of microholes before exposure to the at least the first UV exposure period and the second UV exposure period. 
     
     
         10 . The panel of  claim 9  wherein the light transmissive polymeric material transmits light through the plurality of microholes with a uniformity substantially similar to a uniformity that the light transmissive polymeric material transmits light through the plurality of microholes before exposure to the at least the first UV exposure period and the second UV exposure period when an average of respective light intensities measured through the plurality of microholes is substantially equal to an average of the respective light intensities measured through the plurality of microholes when the light transmissive polymeric material is in a workable state before exposure to the at least the first UV exposure period and the second UV exposure period. 
     
     
         11 . The panel of  claim 9  wherein the light transmissive polymeric material transmits light through the plurality of microholes with a uniformity substantially similar to a uniformity that the light transmissive polymeric material transmits light through the plurality of microholes before exposure to the at least the first UV exposure period and the second UV exposure period when an average of respective optical diameters of the plurality of microholes is substantially equal to an average of the respective optical diameters of the plurality of microholes when the light transmissive polymeric material is in a workable state before exposure to the at least the first UV exposure period and the second UV exposure period. 
     
     
         12 . The panel of  claim 1  wherein the light transmissive polymeric material transmits light through the plurality of microholes with a greater uniformity than a uniformity that the light transmissive polymeric material would transmit light through the plurality of microholes if cured with a single UV exposure period of a same length as a total combined period of the first UV exposure period and the second UV exposure period. 
     
     
         13 . The panel of  claim 1  wherein the light transmissive polymeric material transmits light through the plurality of microholes with a greater uniformity than a uniformity that the light transmissive polymeric material would transmit light through the plurality of microholes if cured with the at least the first UV exposure period and the second UV exposure period and a different rest interval shorter than the rest interval. 
     
     
         14 . The panel of  claim 1  wherein the light transmissive polymeric material has the polymeric chain wherein at least 5% of components are derived from then ultraviolet (UV) curable epoxy acrylate oligomers exposed to the first UV exposure period and the second UV exposure period separated by the rest interval and a third UV exposure period following the second UV exposure period separated by a second rest interval, the second rest interval being a period that extends from the second UV exposure period to the third UV exposure period during which the light transmissive polymeric material is not exposed to the UV source. 
     
     
         15 . The panel of  claim 14  wherein the second rest interval has a same length as the rest interval. 
     
     
         16 . The panel of  claim 15  wherein each UV exposure period of the at least the first UV exposure period, the second UV exposure period and the third UV exposure period has a same length no longer than that of each of the rest interval and the second rest interval. 
     
     
         17 . The panel of  claim 1  wherein each UV exposure period of the at least the first UV exposure period and the second UV exposure period has a same length. 
     
     
         18 . The panel of  claim 1  wherein each of the plurality of microholes is conically-shaped such that the first aperture has a larger diameter than the second aperture. 
     
     
         19 . The panel of  claim 1  wherein the substantially planar portion comprises aluminum or anodized aluminum. 
     
     
         20 . A housing including the panel of  claim 1 , further comprising:
 a light source located within the housing and directed to emit light through the plurality of microholes when lit.