The 78150 beam splitter Holder is used to position a 2 inch [51 mm] square beam splitter or reflector at a 45° angle in an enclosed optical system. Accessing the interior compartment is done from a port located on top of the beam splitter holder. Installing and removing a reflector is an economical and simple method for redirecting the beam path. Beam splitters are generally used with collimated light. If the application requires converging or diverging light at the input or output, the 78150 includes two lens holders, which position 1.5 inch [38 mm] diameter lenses in the optical path. The distance from the lens to the beam splitter is 1.5 inches [38 mm]. The clear aperture of the lens holder is 1.2 inches [30 mm].The 78150 adjusts to fit a beam splitter or mirror up to 0.25 inch [6 mm] thick. The 78150 features four standard Oriel^® 1.5-inch series female flanges and includes a double male coupling ring, allowing it to couple to a variety of Oriel accessories and instruments. With four ports, the 78150 can be positioned so that the split or redirected beam can be directed where needed. Two #1/4-20 threaded holes allow the 78150 to be rod mounted, if flange mounting is not desired. Rod mounting also provides extra support when coupling to the flanges.