Since it can be coupled directly to Oriel ® light sources, monochromators, and detectors via the 1. 5 Inch Series flanges, it is a convenient device for splitting a beam in an enclosed optical system. The 78150 has two lens holders for 1. It is a crucial part of many optical experimental and measurement systems, such as interferometers, also finding widespread application in fibre optic telecommunications. In its. A beam splitter (or beamsplitter, power splitter) is an optical device which can split an incident light beam (e. Beamsplitters are often classified according to their construction: cube or plate. The first surface is coated with an all-dielectric film having partial reflection properties over either the visible or the near-infrared spectrum. 25 inch (6 mm) thick, at a 45° angle.