A beamsplitter is an optical device designed to divide a beam of light into two separate paths—one transmitted and one reflected. This is usually done by applying a thin-film coating on a glass substrate and angling the element relative to the incoming light. 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). Different types of beam splitters exist, as described in the. Quick-reference for beam splitter types, Fresnel equations, polarizing designs, and selection workflow. See the Comprehensive Guide for worked examples, SVG diagrams, and full references.