US Patent 7943862 Method and apparatus for optically transparent via filling

A method and apparatus for filling a via with transparent material is presented, including the steps of providing a panel having a via, occluding the via with transparent material in a workable state so that a portion of the occluding material is internal to the via and a portion of the material is external to said via. The external and internal portions are separated so the transparent filler material, when set, forms a smooth and featureless surface. This causes the filled via to have a substantially even and uniform appearance over a wide range of viewing angles when lit.