A beam splitter (or beamsplitter, power splitter) is an optical device which can split an incident light beam (e. a laser beam) into two (or sometimes more) beams, which may or may not have the same optical power (radiant flux). It is a crucial part of many optical experimental and measurement systems, such as interferometers, also finding widespread application in fibre optic telecommunications. Depending on the application, they can also combine two beams into a single beam. Beamsplitters are primarily categorized into two types, polarizing and non-polarizing, each with its own uses in. When working with lasers, it is often necessary to split a laser beam into two or more defined partial beams.