Beam splitter

A beam splitter is an optical device that separates a single light beam into two partial beams. This property is the beam splitter, among other things to the central component of different types of interferometers. Furthermore, beam splitter, see, inter alia, in binocular attachments, for optical distance measurement, in Justierlasern or laser telescopes of satellite geodesy.

A very simple beam splitter is a glass plate which is placed at an angle of 45 ° in the beam path. A portion of the light is reflected at the surface of the disc at an angle of 90 °, a further portion passes through the washer. By application of a suitable semi-reflecting coating on the surface of the disk, the beam can be divided in this manner into two beams of equal intensity ( half mirror ).

In its common form is a beam splitter made ​​of two prisms, which are at their base (for example, with Canada balsam ) cemented together. The principle on which a beam splitting cube works is prevented total reflection. The division ratio is therefore dependent on the wavelength of light. The thickness of the resin layer determines the ratio at which the incident light beam is divided.

In addition to non-polarizing beam splitters are also polarizing beam splitter ( also called Polwürfel ). The split ratio is determined here by the angle of polarization of the incoming light. Apply Polwürfel in laser technology to provide accurate divider ratios set. Conversely, two polarized light beams can be united with each other.