The VLPC chips are produced by Rockwell [3] and are supplied as 1 x 8 pixel arrays with individual pixels of 1 mm diameter. The first step of the assembly process, done by an outside contractor[4], is to mount and wire-bond the arrays to an aluminum-nitride substrate[5]. The substrate provides the electrical contacts to the VLPC, via metalized castellations. The resulting combination of the substrate plus an 8 channel VLPC array is called a hybrid. Each hybrid is mounted in a molded plastic (Torlon) carrier at FNAL. Care must be taken to align the VLPC pixels (1 mm diameter on 1.05 mm centers) with holes (for later insertion of light-guide fibers) in the Torlon carrier. This is accomplished by a high-resolution video alignment system which provides mounting accuracies of 10 micron and thus assures that later the fibers are centered on the pixels to the required accuracy. It is in this form, as a hybrid mounted in a Torlon carrier, that the VLPC's are tested and characterized.