A beam splitter is an optical device that divides a single incoming beam of light into two or more separate beams. The split ratio of light transmittance and reflectance is 1:1 and is called a half mirror. Beam splitters are very common optical components which can be used for different applications, such as interferometer, autocorrelation,camera,photographic,laser systems,illuminator. A beam splitter divides a beam of light with a semi-reflective coating to create two beams for you to observe, analyze, or image.