The simplest configuration for a beamsplitter is an uncoated flat glass plate (such as a microscope slide), which has an average surface reflectance of about 4 percent. It is a crucial part of many optical experimental and measurement systems, such as interferometers, also finding widespread application in fibre optic telecommunications. a laser beam) into two (or sometimes more) beams, which may or may not have the same optical power (radiant flux). Beamsplitters are generally effective at reflecting s-polarization but they are not as effective at preventing p-polarization from reflecting. This. The elements of the beam splitter transformation matrix B are determined using the assumption that the beamsplitter is lossless.